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Surname or Family name: CUMMING Firstname: Steven Othername/s: ~()nald Abbreviation for degree as given in the University calendar: Ph • 0 School: Psycho 1ogy Faculty: Life Sciences

Tide: The familiarity of repeated words: conscious and unconscious contributions to repetition priming

Abstract 350 words maximum: (PLEASE TYPE)

Six experiments are described which investigate the role of conscious and unconscious memory mechanisms in repetition effects for high and low frequency words and legal nonwords The definition and role of 'familiarity' in priming is particularly elaborated upon. Experiments 1 and 2 directly investigate recognition memory and familiarity for repeated masked words,. They suggest a paradoxical inhibition of 'familiarity' results from repetition of masked words. Experiments 3 and 4 develop a novel lexical decision task, which isolates the effects of repeated presentation and response components. Repeated presentation and repeated responding are found to interact with word frequency and lexicality, suggesting that repetition priming of words and nonwords may arise through different aspects of the priming experience. In Experiments 5 and 6 this procedure is extended to investigate the transfer of repetition effects to later memory tasks. The retrieval tasks permit estimation of 'recollective' and 'familiarity' components according to Jacoby's (1991) Process Dissociation procedures.

It is suggested that an additional aspect of familiarity- termed 'contextual specificity' interacts with any pre-experimental familiarity (baseline frequency) and item may have to produce over-and underadditive relationships between repetition condition, frequency or lexicality and estimated familiarity. The process-dissociation operationalisation of 'familiarity' is also challenged, particularly as is obtains to pre-experimentally novel stimuli

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THIS SHEET IS TO BE GLUED TO THE INSIDE FRONT COVER OF THE THESIS ST 401.9 402 The familiarity of repeated words:

Conscious and unconscious contributions to repetition priming

Steven Cumming

March, 1998

This thesis is submitted in partial fulfilment of the requirements of Doctor of

Philosophy, University of New South Wales. UNSW 1 6 JUl 1999 LIBF!ARY I hereby declare that this submission is my own work and that, to the best of my

knowledge and belief, it contains no material previously published or written by

another person nor material which to a substantial extent has been accepted for

the award of any other degree or diploma of a university or other institute of

higher learning, except where due acknowledgment is made in the text.

CERTIFICATE OF ORIGINALITY

I hereby declare that this sub . . . knowledge it con rains no ma=on IS. my own ":'ork and to the best of m person, nor material which to a subst!~;ously pubhshed or written by anoth; of any other degree or diploma at UNS:;x~nt has been accep~ for the award except where due acknowledg . .or any other educational instiiUti to th ement IS made m the th . on, . e. research by others, with whom l hav CSIS. Any contnbution made exphcJtly acknowledged in the thesis. e worked at UNSW or elsewhere, is

I also declare that th · e m~lleCIUal content of th · . . work, e~cept to the extent that assislance fro IS thCS!s. IS the product of my own concepbon or in style, Presenration and lin .Ill_ others m_ th~ project's d~gn and gtllstic ex.press•on IS acknowledged. Acknowledgements

I would like to thank my thesis supervisor, Associate Professor Sally

Andrews, for her energy, enthusiasm, support and friendship. I am also

indebted to the hundreds of undergraduates who volunteered for the studies

and my friends and colleagues at the University of New South Wales, Charles

Sturt University and the University of Sydney, who have provided support and

assistance over many years.

I also gratefully acknowledge the support, tolerance and encouragement

of my family, especially my wife, Rosalie, my daughter Gemma, my mother and my father, whose quiet pride in his children has inspired us all. CONTENTS

ABSTRACT 6

CHAPTER 1: FAMILIARITY AND UNCONSCIOUS PROCESSES 7

1.1 Information processing without conscious awareness 7

1.2 Methods for investigating conscious and unconscious knowledge. 9

Data limited stimulus presentation. 9

Critique of data limited procedures. 14

Awareness at the time oftesting: direct and indirect retrieval 15

1.3 Theoretical approaches to dissociations between familiarity and recollection. 19

Multiple Systems Perspectives 20

Multiple process perspective 23

1.4 Integration of systems and process perspectives 28

Differential sensitivity of direct and indirect measures. 28

Perceptual representation systems. 29

1.5 Repetition priming. 30

Episodic contributions to repetition priming 31

'Phenomenal' and 'instance-specific' episodic memory 32

'Lexical' accounts of repetition priming. 36

Mechanisms of repetition priming 37

Word frequency effects. 40

Nonword repetition priming 42

1.6 Single process models 44

The REM Model 45

1 Counter Model 47

1.7 Connectionist approaches. 48

1.11 The present experiments 49

CHAPTER 2: EXPERIMENTS 1 AND 2 51

2.1 Familiarity and recognition failure. 51

Repetition, familiarity and recognition 53

2.2 Preliminary study 57

Results: 58

2.3 Experiment 1 60

Method. 61

Results. 63

Discussion. 66

2.4 Experiment 2. 67

Method. 69

Results. 70

Discussion, Experiments 1 and 2. 73

Familiarity accrues with repetition 74

Recognition does not require familiarity 74

Chance performance in recognition and familiarity 76

Significant correlations between recognition and familiarity. 77

2.5 The direct familiarity task 79

2.6 Theoretical implications: Experiment 1 and 2 81

Response bias 81

Inhibitory mechanisms 82

2 CHAPTER 3. EXPERIMENTS 3 AND 4 90

3.1 Rationale and Overview: Experiments 3 to 6 90

3.2 Experiment 3 92

Method. 93

Results. 96

Discussion. 99

3.3 Experiment 4. 102

Method 102

Results 103

3.4 Discussion: Experiments 3 and 4. 106

Lexical status 107

Word frequency 111

CHAPTER 4: DISSOCIATING FAMILIARITY AND RECOLLECTION

114

4.1 Process Dissociation (Opposition) procedures. 115

Task and process dissociations. 115

Process Dissociation. 116

4.2 Applications of Process Dissociation Procedures 119

4.3 Process Dissociation: Critique and Review 122

Lack of defmitional clarity. 122

Poor control of guessing and response sets. 123

The independence assumption. 124

Equivalence of inclusion and exclusion tasks. 127

4.4 Alternative conceptualisations of process dissociation 128

3 Exclusivity Model. 128

Redundancy Model 128

Integrating the independence, exclusivity and redundancy models. 130

CHAPTERS 133

EXPERIMENTS 5 AND 6 133

5.1 Experiment 5 13<&

Method. 137

Results. 142

Discussion 155

5.2 Experiment 6. 160

Method 163

Results 164

Discussion 172

5.3 Conclusions from Experiments 3 to 6. 174

Simple repetition. 175

Differential Word and Nonword repetition effects. 175

Response repetition. 179

5.4 Repetition effects in memory. 180

CHAPTER 6: GENERAL DISCUSSION 184

6.1 Familiarity and perceptual fluency. 184

Repetition, frequency and familiarity 184

Baseline and intra-experimental familiarity 184

6.2 The Process Dissociation operationalisation of familiarity. 186

4 Process dissociation and nonword familiarity 187

The Redundancy model 190

6.3 Study Task Differences 194

6.4 Contextual specification. 195

Intra-experimental familiarity and specification. 197

Specification and word frequency 197

6.6 Electrophysiological support for specification 199

6. 7 Conclusions 203

REFERENCES 206

APPENDICES 223

5 ABSTRACT

Six experiments are presented which investigate the role of conscious and unconscious memory mechanisms in repetition effects for high and low frequency words and legal nonwords. The definition and role of 'familiarity' in priming is particularly elaborated upon. Experiments 1 and 2 directly investigate recognition memory and familiarity for repeated masked words.

They suggest a paradoxical inhibition of 'familiarity' which results from repetition of masked words. Experiments 3 and 4 develop a novel lexical decision task that isolates the effects of repeated presentation and repetition of response components. Repeated presentation and repeated responding are found to interact with frequency and lexicality, suggesting that repetition priming of words and nonwords may arise through different aspects of the priming experience. In Experiments 5 and 6 this procedure is extended to investigate the transfer of repetition to later memory tasks. The retrieval tasks permit estimation of recollective and familiarity components according to

Jacoby's (1991) process dissociation procedures.

It is suggested that an additional aspect of familiarity- termed

'contextual specificity' interacts with any pre-experimental familiarity (baseline frequency) an item may have to produce over-and underadditive relationships between repetition condition, frequency or lexicality and estimated familiarity.

The process dissociation operationalisation of 'familiarity' is also challenged, particularly as it obtains to pre-experimentally novel stimuli.

6 Chapter 1: Familiarity and unconscious processes

1. 1 Information processing without conscious awareness

We do not have complete subjective access to the cognitive processes intervening between stimulus and response. Reading a word, for example, involves a set of processes of which we have only scant subjective awareness. Nonetheless, we do feel that consciousness, or awareness of our psychological processes, is relevant to information processing. When trying to recall the name of the capital of Sri Lanka, for instance, we presume that conscious, effortful remembering is more likely to yield a result than passively relying on spontaneous recall.

Differences between information processed within and outside of consciousness have been a focus of much of the history of psychology.

Forces beyond the conscious experience of the individual, which nonetheless motivate complex behaviour are the cornerstone of psychoanalytic psychology (e.g. Freud 1962), models of dissociative states (e.g. MacMillan,

1990) and hypnotic phenomena (Kihlstrom, 1992).

The concept of an active, behaviorally and cognitively potent unconscious has also shaped public opinion regarding the power and influence of the media. Since the 1940's, descriptions of usubliminal perception' phenomena have resulted in a contemporary presumption that a message presented in such a way as to prevent its availability to awareness

7 at the time of presentation can powerfully influence consumer, criminal, and

social behaviours (e.g. Morse & Stoller, 1982; Dixon, 1981; Vance et al. Vs

Judas Priest et al., 1990).

Such a view suggests that the unconscious is not only active in

parallel with conscious processing, but is often the primary motivating force in

human behaviour. An alternative position acknowledges the relevance of

nonconscious processes, but challenges the suggestion that such processes extend much beyond overlearned, automatic and stereotyped detection and analysis. These competing positions as to the potency and determinism of unconscious processes are crystallised by Loftus and Klinger (1992) into the question: Is the unconscious smart or dumb?

As early as 1958, in their review of the evidence regarding 'subliminal perception' phenomena to that date, McConnell, Cutler & McNeil (1958) concluded that while there is evidence that cognitive operations are performed on items presented beyond conscious awareness, there is little evidence that these operations are sophisticated or behaviourally compelling.

The flurry of claim and opinion about the effectiveness of subliminal methods seems to be based more on enthusiasm than controlled scientific experimentation. The course of scientific history is strewn with the desiccated remains of projects pursued with more vigour than wisdom. (McConnell et al. 1958, p239)

A Science Watch series of papers in American Psychologist (1992) reviewed of the current status of the psychological unconscious in experimental psychology. The authors (e.g. Erdelyi, 1992, Merikle, 1992,

Greenwald, 1992) contrast the contemporary view of an empirical, estimable

8 and wholly unremarkable unconscious with the sinister, mythologised and

threatening psychodynamic unconscious. Greenwald (1992), for instance

argues that the 'smart' dynamic unconscious has not been demonstrated

empirically. While there is certainly information processing outside of conscious awareness, Greenwald (1992) concludes that it involves relatively simple analyses such as the activation of meanings of single words.

1. 2 Methods for investigating conscious and unconscious knowledge.

Within experimental psychology, the relationship between information processing with and without conscious awareness been addressed from a number of methodological and theoretical frameworks. The six experiments to be described here draw their definitions and operationalisation of familiarity from three broad research paradigms: the literature concerning brief or masked stimulus presentation, the dual (or multiple) process perspective in memory research, and the psycholinguistic distinction between abstract and episodic representations of words. Connectionist approaches to memory are also discussed. Each of these perspectives is presented more specifically in the introductions to specific experiments, but all are presented in overview in the following sections.

Data limited stimulus presentation.

One method used to investigate unconscious processing evaluates sensitivity to stimuli for which no conscious processing was possible at the time of initial stimulus presentation. A range of methodologies such as

9 auditory divided attention (Eich, 1984), dichotic listening and parafoveal

presentation (Dallas & Merikle, 1976) have been used. The present review

will focus upon studies using backward masking and/or rapid visual

presentation.

Masked words. The relationship between subjective experience and

unconscious processes has been explored under conditions where

participants report no conscious experience of a stimulus, yet appear to show evidence of complex analysis, synthesis and integration of that stimulus.

Marcel, Katz & Smith (1974) reported that errors in masked word recognition tasks tended to be similar in meaning to the target word.

Participants in their study were encouraged to identify or guess any words or letters they could discern from a briefly presented masked stimulus. A significant number of the errors produced were regarded by the investigators as being semantically related to the target, despite bearing no physical or phonological similarity to it. For example, the masked item JOY, which the participant reported not having seen at all, was guessed as HAPPY. Similar findings were reported by Allport (1977). Although semantically related errors to masked items were rare, Allport argued that they nonetheless occurred above chance. He suggested that people have access to the meaning of the word even when backward masking disrupts all conscious access to the physical features of the stimulus.

However the interpretations given to both of these studies have been challenged by the finding that participants who were not shown the target at all (ie. true guessing) produce responses which are semantically related to

10 the (nominal but in fact unpresented) 'target' at about the same rate as that

obtained by Allport (1977) for masked targets (Ellis & Marshall, 1978, Marcel,

1980). Ellis and Marshall (1978) concluded that the effects obtained by

Allport (1977) were most likely the result of a liberal criterion for 'relatedness'.

Nonetheless, Marcel (1980, 1983a) argued that even using a more restrictive criterion for relatedness, the occurrence of semantically related errors in the

Marcel et al. (1974) paper is 'considerably' (Marcel, 1983a, p201) greater than chance responding.

In a more systematic series of studies Marcel (Marcel and Patterson,

1978; Marcel, 1983a) presented pattern masked words at very brief exposures. At durations at which they reported themselves to be guessing as to the presence or absence of the target prior to the mask, participants were able to make forced choice judgements about which of two words was more strongly semantically related to the target with above chance accuracy. It was argued that stimuli presented at a duration too brief to permit conscious awareness (indexed by detection) are nonetheless processed to the level of meaning, and therefore that access to semantic content is dissociable from conscious awareness.

This evidence led Marcel (1983a, 1983b) to conclude that two independent processing systems exist: a consciously accessible route giving rise to a psychological percept and intentional action, and an unconscious route resulting in semantic activation and information processing. Masking disrupts or eliminates the conscious route, but has no impact upon the unconscious route.

11 However, the finding that word meanings are processed more quickly than a number of apparently more elemental features of words may be attributable in part to the compelling nature of the extraction of meaning from known words. Even within fully conscious processing, well known phenomena such as the Stroop Effect (Stroop, 1935) demonstrate that skilled readers extract word meanings in a highly automated fashion, and can do so at least as quickly as extracting simpler features such as word colour. Adult readers are more practised at reading words for meaning than at identifying other characteristics that they may have. As such, it may not be surprising that meaning can be processed at exposure durations too brief to permit other judgements.

Briefly presented nonlexical items. The case for a dissociation between conscious and unconscious processes would be stronger if novel stimuli could be demonstrated to show evidence of complex processing in the absence of conscious detection, because such findings could not be attributed merely to overlearned semantic analysis of words. In a series of studies Kunst-Wilson and Zajonc (1980) investigated memory for briefly presented 'nonsense shapes' (irregular polygons) displayed for only 1 millisecond. In a subsequent forced-choice test, participants were shown an old and a new stimulus and required to indicate which they liked better and which they had been shown before. Confidence ratings were then performed for both judgements.

Under these conditions, participants were unable to recognise the old polygons. However, they chose the old items significantly more often than

12 chance in the preference task. Furthermore, on trials where participants rated

themselves to be 'just guessing', recognition and preference were both at

chance. As confidence ratings increased, probability of correct recognition

remained at chance, but the probability of selecting the old item as preferred increased. Kunst-Wilson and Zajonc concluded that:

.. there may exist a capacity for making affective discriminations without extensive participation of the cognitive system. (1980, p558),

A series of authors have replicated and extended the Kunst-Wilson and Zajonc (1980) findings. Seamon, Brody and Kauff (1983a, 1983b) replicated the earlier experiment using both backward masked stimuli and divided attention conditions. Although their findings replicated those of Kunst-

Wilson and Zajonc, their results suggested that preference judgements exceeded recognition only for stimuli presented to the right visual field.

Seamon et al. (1983b) concluded that, rather than supporting a difference in how stimuli are processed initially, the dissociation between preference and recognition judgements is based upon differences between the retrieval tasks.

Items are selected in the preference condition not because they are truly preferred, but because they are familiar. Seamon et al (1983b) argued that the effects are attributable to the ease with which previously processed stimulus configurations are reprocessed (relative perceptual fluency, see below), even though they are not consciously available for recall.

A similar argument was made by Mandler, Nakamura and Van Zandt

(1987), who demonstrated that under such restricted presentation conditions, participants show above chance selection of old stimuli on almost any

13 evaluative criterion, whether affective or not. Mandler et at. used a similar

presentation paradigm to that of Kunst-Wilson and Zajonc (1980). Their test tasks included not only recognition and preference, but also ratings of which

item seemed brighter or darker. In all forced choice selection tasks except recognition, participants favoured the old item (although in the 'darker' condition selection was not significantly above chance, it was greater than the complement of the 'brighter' condition, suggesting a general bias in favour of the old polygons). Mandler et at (1987) concluded stimuli lost to consciousness are nonetheless 'activated', (see below) and residual activation forms the basis of selection in the comparative and evaluative judgements.

Critique of data limited procedures.

However, the general experimental program into activation without conscious awareness has met with considerable criticism, at both methodological and conceptual levels. Prior to the publication of Marcel's major findings (Marcel, 1983a, 1983b), some of both his and Allport's (1977) results had been demonstrated to be largely artefactual or unreplicable (Ellis and Marshall, 1978; Fowler, Wolford, Slade and Tassinary, 1981). Fowler et at. (1981) highlighted methodological shortcomings of Marcel's original experimental series, but nevertheless replicated his key findings under more rigorous conditions.

General methodological criticisms include the selection, intra-session organisation and comparability of tasks used to assess activation and awareness (Humphreys, 1981; Cheesman and Merikle, 1986) and the

14 operationalisation of 'subthreshold' presentations (Holender, 1986; Reingold

and Merikle, 1988; Dunn & Kirsner, 1989). Techniques for establishing

participants' thresholds for awareness of stimuli have been a particular focus of criticism. Threshold setting and experimental trials have often taken place at different times in the session. Participants therefore had different periods of dark adaptation, and consequently experienced different luminance conditions when the 'threshold' is established from when the 'subthreshold' stimulus presentation occurs.

In addition to such specific methodological criticisms Holender (1986) raises the essentially philosophical concern that investigation of the contents of conscious thought must rely to some extent on the reported experience of the subject; an introspective methodology which he regards as scientifically regressive.

Nonetheless, the important feature of the findings reviewed above is not that they necessarily demonstrate cognitive activity beyond 'conscious awareness', but rather that they appear to demonstrate that stimuli presented under highly data limited conditions can be demonstrated to influence performance in a number of memory tasks, but are not endorsed in recognition memory tasks. To this extent, the results from studies using briefly presented stimuli suggest a dissociation between memory tasks that parallels the dissociation between 'direct' and 'indirect' memory tasks as described in the following section.

Awareness at the time of testing: direct and indirect retrieval

The second body of evidence regarding unconscious processing

15 centres upon· memory for items that are not consciously available for retrieval,

even though they were clearly presented and consciously processed at the time of encoding. Studies exploring "indirect" or "implicit" memory

phenomena allow inferences to be drawn regarding the role and nature of

unconscious, automatic processes in retrieval

A large and widely cited experimental literature has developed attempting to account for apparent dissociations between conscious and non­ conscious processes in recall. The distinction has been captured by a number of different terms, the most generally used of which are "direct/ indirect" and "explicit/implicit".

Although used largely interchangeably, the terms 'direct' or 'indirect'

(Johnson & Hasher, 1987), and 'implicit' or 'explicit' (e.g. Graf & Schacter,

1985; Tulving & Schacter, 1990) can be argued to have different referents. A retrieval task is characterised as direct or indirect according to the extent to which participants are required to deliberately retrieve material from the study condition at the time of test. In practice, this distinction is operationalised by classifying tasks in which participants are instructed to retrieve items from a previously presented list as 'direct' tests, and those in which they are not told that memory for the list is being tested as 'indirect' tests.

The same general definition applies to the 'implicit/explicit' distinction, and for most practical purposes the terms are substitutable. However many authors (e.g. Richardson- Klavehn & Bjork, 1988, Dunn & Kirsner, 1989;

Reingold & Merikle, 1990, 1991) have noted that the terms 'implicit' and

'explicit' are ambiguous, because they can be taken to characterise both the

16 organisation of the task ("the memory test was implicit in the priming task") or the nature of the trace thought to be accessed by the task ("a test of implicit

memory"). The term therefore implies a yoking of the measurement task with the theoretical construct that has not been empirically demonstrated. It must be established that a distinctive "implicit" memory trace exists at all, before considering whether "implicit" memory tasks access this and no other trace

(for further discussion of this distinction see Richardson-Klavehn & Bjork,

1988; Schacter, 1990). A task could be 'implicit' in the procedural sense without necessarily measuring a construct called 'implicit memory'.

While a similar argument can be directed towards the 'direct/indirect' classification, the labels themselves are less ambiguous. Tasks can access memory directly or indirectly, but memory systems cannot be usefully characterised as direct or indirect. The direct/indirect distinction is preferable because it refers to a distinction between tasks only and does not presume any underlying taxonomy of memory.

Standard tests of recognition and free recall, in which participants are told to select or generate items from a previously seen list, are direct tasks.

Completion and identification tasks are commonly used indirect measures, although any task whose instructions do not directly refer to the study phase is indirect. Thus tasks as diverse as fragment completion (eg, Graf, Mandler

& Haden, 1982) ,preference judgements (e.g. Mandler et al. 1987), Lexical

Decision (e.g. Carroll & Kirsner, 1982) or semantic relatedness judgements

(e.g. Marcel, 1980}, can all be utilised as indirect tests of the effect of prior experiences.

17 Dissociations between performance on direct and indirect memory

tasks have been widely described (for reviews see Graf, Shimamura &

Squire, 1985; Squire, 1992; Schacter, 1992). Perhaps the most striking is the

finding that certain patients with damage to medial temporal and diencephalic

structures, show markedly impaired direct memory functioning ("amnesia"), even though their performance in indirect memory tasks is normal

(Moscovitch, Winocur & McLachlan, 1986; Squire & McKee, 1992; Graf,

Squire & Mandler, 1984).

In one of the earliest demonstrations of this dissociation, Warrington and Weiskrantz (1968) used a paradigm in which participants were taught a list of words and then provided with either a direct (recognition) or indirect

(fragment completion) memory test. They observed that many of the participants with amnesia had no recollection at the time of testing that the initial list had ever been presented, and therefore felt themselves to be

'guessing' in the memory tasks. Nonetheless, in many cases they demonstrated normal rates of completion of fragments with old items. This finding quite closely parallels those described above from masked presentation studies with nonclinical samples. As Schacter (1987) notes:

These findings come either from studies of amnesic patients or from experiments in which normal participants are prevented from encoding target materials in a fully conscious or elaborative manner. (1987, p 510) Among normal subjects indirect memory performance is independent of levels of processing manipulations at the time of encoding, unlike direct memory, but is more sensitive than direct memory to manipulation of stimulus features and modality (Jacoby, 1983, Jacoby & Dallas 1981, Kirsner & Smith,

18 1974).

For example, Jacoby (1983) compared the retrieval of words read out

of context with those generated from a semantic context. He found that

reading a word facilitated subsequent indirect memory performance

(perceptual identification), but left recognition unchanged, while generation of the word enhanced recognition memory but not perceptual identification.

Several authors have replicated and extended this general finding (Weldon &

Roediger, 1987; Blaxton, 1989; although see Challis & Brodbeck, 1992, for contrary evidence),

1. 3 Theoretical approaches to dissociations between familiarity and recollection.

Regardless of specific criticisms and methodological disputes, there is a remarkable compatibility between the results from studies using data­ limited presentation - in which access to conscious processing is restricted at the time of stimulus presentation- and those investigating direct and indirect memory- where the critical variable appears to be the conscious access to the studied stimuli at the time of test. These literatures converge upon the construct of 'familiarity' - our subjective experience that we have encountered an item before- as an important aspect of nonconscious processing, but operational and theoretical definitions of "familiarity" remain a focus of controversy in both domains. As will be discussed in more detail in the following chapters, distinctions between familiarity and other processes in memory, and between different varieties of familiarity emerge as a central

19 theme in the investigation of the contribution of conscious and nonconscious knowledge to memory processes. Items masked at presentation are familiar, and that familiarity is reflected in subsequent evaluative choices. Items which are not consciously retrievable at the time of test are similarly familiar, and that familiarity forms the basis of subsequent indirect memory task performance. This converging evidence has been approached from a number of empirical and theoretical perspectives, and a variety of accounts of the role of familiarity in a wide range of judgements have been offered.

Multiple Systems Perspectives

Although the present experiments do not directly test between

'systems' and 'process' views of direct and indirect memory, the distinction is important in understanding the particular methodologies which have been adopted.

As outlined above, dissociations have been obtained between the direct and indirect memory performance of amnesic populations. This evidence tends to support the view most strongly identified with Tulving and

Squire (e.g. Tulving, 1985, Cohen & Squire, 1980, Squire, 1992 ), that direct and indirect memory performance represent the activity of independent memory systems, with each system subserved by separate brain structures.

According to this view, a single event is held to be simultaneously represented in several memory systems, with transfer and consolidation of memory between and within systems. Direct memory is generally identified with diencephalic structures and indirect memory with non-hippocampal neocortex (See Squire, 1992 for a synthesis of findings from three animal

20 species).

As the majority of patients with organically-based amnesia show

damage or dysfunction to structures such as the hippocampus and

mammilliary bodies (e.g. Zola-Morgan, Squire & Amaral, 1986; Zola-Morgan

& Squire, 1986; Perani, Bressi, Cappa, Vallar, Alberoni, Grassi, Caltagirone,

Cipolotti, Franchesci, Lenzio & Fazio, 1993) this 'multiple systems'

perspective is consistent with numerous findings from clinical neuropsychology. Furthermore, Gabrieli, Fleischman, Keane, Reminger, &

Morrell (1995) claimed to have completed a double dissociation of function within memory systems and brain structures. They reported on a patient with a large right occipital lobe lesion who had impaired indirect perceptual memory and intact direct retrieval, the first patient described in the literature with this combination of intact and impaired memory functions. This complements the more common finding of impaired direct memory and intact indirect memory following diencephalic lesion.

The apparent redundancy associated with this duplication of memory systems is in part addressed by McClelland, McNaughton & O'Reilly (1995), who offer a connectionist account of the multiple systems theory. They contrast the architectures of hippocampal and nonhippocampal neocortex, and suggest that distributed patterns of activation in the neocortex are compressed and rerepresented in the hippocampus, with bidirectional transfer of activation occurring during 'offline' periods such as slow-wave sleep. The compressed representation would provide a 'summary sketch' of more distributed patterns of neocortical activity. Within such a model, the role of

21 the hippocampal system is to permit rapid acquisition and generalisable

retrieval of task-relevant information, while memories in the neocortical

system directly represent connections between features of the encoding

context. The slow rate of acquisition shown by those with hippocampal amnesia (e.g. Milner, Corkin & Teuber, 1968),and the sensitivity of indirect memory to contextual and structural changes in stimuli (Jacoby & Dallas

1981 ), can be explained within such a model.

Note, however that McClelland et al. do not present original evidence for a multiple systems model. Rather they present a version of the model in which dual representation of knowledge is nonredundant, because both the hippocampal and neocortical systems serve different adaptive purposes.

They do not attempt to support or contrast this model against competing cognitive, neuroanatomical or architectural models.

Because of the historical connections between the systems perspective and localist neuropsychological findings, the multiple systems perspective presumes that the distinction between explicit and implicit memory systems is more important than distinctions between tasks accessing each system. However, Witherspoon and Moscovitch (1989) obtained

'dissociations' within the group of indirect memory tasks that were of at least the same magnitude as the dissociations obtained between direct and indirect tasks. While this does not directly contradict predictions from the systems perspective, it does suggest that at least a proportion of the cognitive evidence for a structural dissociation may be attributable to . task-based differences.

22 Multiple process perspective

The contrasting view - that task differences account for much of the dissociation between direct and indirect memory performance - has been referred to as the multiple processes perspective (Roediger & Blaxton, 1987;

Blaxton, 1989). The multiple process view maintains that the differences between direct and indirect memory are attributable to the different types of processing recruited at study and test for the two tasks. As such, they are an extension of established principles of memory functioning such as encoding specificity and transfer-appropriate processing (Morris, Bransford & Franks,

1977). In general, those who advance a multiple processes perspective draw more heavily from studies of normal memory than amnesia. As evidence for the processing framework tends to come from studies using participants without memory impairment, 'dissociations' are typically between types of encoding and retrieval task, rather than between memory pathology groups.

However, there are differences between varieties of multiple process accounts, and dispute as to the appropriate characterisation and description of the processes themselves.

Activation and integration: Mandler. Mandler (1980, 1989, Mandler

Hanson & Dorfman, 1990), for instance argues that the distinction between conscious and non-conscious processing reflects different and parallel processes within the memory system, that he labels "activation/integration", and "elaboration".

Activation or integration arises from the mere presentation of a stimulus. It is an automatic process which results in an increment in activity

23 within all perceived features of an event and integration across those

features, such that all are more easily processed together on subsequent

encounters. While Mandler regards activation and integration as a single

event, the extent to which any single processing occasion can be described as predominantly activating or integrating will vary as a function of the novelty of the event being processed. For old, previously acquired stimuli such as words, each new exposure is better regarded as activation, while for novel stimuli, the association between features has not yet been established, so the process is better described as integration. Activation/integration does not require effortful or strategic encoding, and, as it relies upon perceptual and configura! properties of the original presentation, is facilitated by commonality between the studied and tested version of the stimulus.

Elaboration 'usually' (Mandler et al. 1990) requires conscious organisation of multiple events, such that the event is contextually and chronologically indexed. It is influenced by cognitive effort and the application of attention, and is therefore affected by manipulations such as divided attention, levels of processing and mnemonic strategies. Items are available for retrieval to instruction as a function of their degree of elaboration.

Bonanno and Stillings (1986) explicitly tested the role of integration and elaboration in the Kunst-Wilson and Zajonc (1980) phenomenon

(preference for briefly presented unrecognised stimuli) by asking participants to identify the octagon that seemed more familiar to them. Both preference and recognition conditions were also included. Participants demonstrated above chance selection of the old items when asked to indicate either

24 preference or familiarity between the two stimuli, but recognition performance

remained at chance, suggesting that, with re-presentation, the old octagons were readily activated even though they had not been elaborated at the time

of presentation.

Thus in contrast to Marcel's (1983a, 1983b) division of cognitive processing into a conscious and an unconscious component, and Kunst­

Wilson and Zajonc's (1980) distinction between 'cognition' and 'affect',

Mandler et al. (1987) and Bonanno and Stillings (1987) argued that items presented under circumstances which impede conscious processing are retrievable in tasks that rely upon activation, even when they are not consciously recognisable.

Perceptual fluency: Jacoby. A slightly different version of the two process model is advanced by Jacoby (1991, Jacoby & Dallas, 1981). Rather than attributing familiarity to the activation of a learned trace of the stimulus features, Jacoby argues that familiarity arises because the participant is familiar with the act of processing the stimulus, a phenomenon he labels

'perceptual fluency'. Fluency is not strictly a representation of the stimulus, but rather a record of the operations engaged when the stimulus was processed. As such, there is no 'activation' in the Jacoby model. Items are processed more efficiently on later encounters because they have been processed before. Perceptual fluency is the facilitation arising from the application of recently applied procedures, with the degree of facilitation being a function of the extent of procedural overlap associated with the two processing occasions. Indirect memory phenomena arise because the

25 participant finds it easier to produce a response based upon the overlap with

those procedures engaged when the original stimulus was processed.

For a fluently processed item to be regarded as familiar, the

increased fluency must be presumed to derive from a recent experience with the item. Jacoby and others (e.g Jacoby 1988, Jacoby and

Whitehouse, 1989) have demonstrated that an 'illusion' of familiarity can be

produced under conditions where subjects are lead to misattribute their increased perceptual fluency. The best known of these phenomena is the

'false fame effect' (Jacoby , Woloshyn and Kelley, 1991), in which a manipulation of attention during study results in subjects confusing recently presented nonfamous names with famous names.

Criticism of the Mandler dual-process model has tended to focus upon the activation/integration rather than the elaborative component. The time course of decay of the activation process appears longer than is plausible. Evidence for indirect memory can be obtained hours or days subsequent to the initial exposure (eg Kolers, 1976). A system with such enduring activation would very quickly reach a state in which every perceptual experience would remain highly active.

The Jacoby model is more difficult to challenge, as it does not require a series of activated traces, only a perceptual system which is altered by processing occasions. By proposing that fluency-based responding is increased as a function of the perceptual overlap between the stimuli presented at study and that used at test, it makes predictions which are consistent with existing transfer-appropriate processing accounts of normal

26 memory functioning.

Data driven and conceptually driven processes: Roediger. Roediger

(1990, Roediger and Blaxton, 1987a, 1987b, Roediger & Weldon, 1987)

invoked a distinction between conceptually driven and data driven processing to account for many of the observed dissociations both between and within direct and indirect tasks. Conceptually driven processing relies upon elaboration of the stimulus. It requires that the subject make contact with the meaning and implication of the presented item. Data driven processing is essentially perceptual, and is based upon the perceived features of the presented stimulus. Within this distinction, free recall is a conceptually driven task, since the subject is asked to reproduce the stimulus without being presented with any of its perceptual features. Tasks in which features of the original stimulus are re-presented at test, such as identification or completion procedures, require data-driven processing.

Direct tests such as recall are typically conceptually driven, while indirect tests such as perceptual identification or fragment completion are data driven. Roediger (1990) presented a series of studies in which the engagement of data driven and conceptually driven processes at study and test were systematically manipulated. Consistent with transfer-appropriate processing principles, he found that memory performance is dependent upon the extent to which corresponding processes were engaged by the study and test tasks, rather than by the absolute categorisation of the task as direct or indirect.

Thus it is argued that apparent dissociations between memory tasks

27 may arise more from cognitive differences between the tasks themselves rather than from the activity of different memory systems. The distinction between task and process dissociations is reviewed further in Chapters 4 and

5.

1.4/ntegration of systems and process perspectives

The distinction between system and process approaches becomes somewhat blurred as each position attempts rapprochement. The most compelling evidence for the multiple systems view derives from single and double dissociations of memory function with identified brain injuries. As a proponent of the processes view, Roediger (1990, Roediger Weldon &

Challis, 1989) acknowledges that amnesia studies present a challenge to the process model, but argues that even within a single system, there may be many dissociable processes which must be separately conceptualised and operationalised. If one accepts Roediger's argument that there are many memory processes invoked by a single task, it would nonetheless appear that these processes are differentially disrupted by, for example, hippocampal damage. It is very difficult to distinguish theoretically between a multiple process approach with different processes preferentially utilising different structures, and a multiple systems approach.

Differential sensitivity of direct and indirect measures.

Another approach to reconciling systems and process positions is to examine more closely the differences between typical direct and indirect memory tasks, especially when they are applied to the memory impaired.

28 Ostergaard (1994, Ostergaard & Jernigan, 1996) attributed the differences

between amnesic and nonamnesic participants to differences in the sensitivity

of direct and indirect measures. By definition, amnesics have difficulty with

memory tasks, and may have other specific processing deficits. If typical direct memory tasks happen to be more difficult than typical indirect tasks, the difference between direct and indirect task performance will be amplified for the amnesic groups. Ostergaard (1994) found that if relative difficulty of test tasks is taken into account, amnesics' performance on an indirect (priming) task is as impaired as their performance in direct tasks, challenging the

'dissociations' which provide a cornerstone of the systems perspective.

However, the validity of Ostergaard's procedures for calibrating task baselines is vigourously disputed by Tulving and colleagues (e.g. Tulving,

Hayman & Gordon, 1995)

Perceptual representation systems.

Schacter (1989) has also suggested a model which reconciles the systems and process models, although it is a reconciliation which, if anything, increases the number of postulated systems, while identifying them with specified processes. Recruiting evidence from a range of neuropsychological syndromes involving apparent retrieval failure, he argues that perceptual input is doubly encoded. A context-specific, retrievable code is represented in episodic memory, and the processing experience is also encoded into perceptual representation systems, which maintain the perceptual properties of the encoding stimulus. It is these perceptual systems which are accessed by perceptually-based 'data-driven' tasks. Schacter enumerates two such

29 systems: one which preserves word form independently of word meaning (the word-form system) and one which preserves visually presented images (the structural description system). The addition of these systems to existing taxonomies of memory processes would account for many of the apparent dissociations both within and between direct and indirect memory tasks. In

Schacter's model, transfer-appropriate processing applies at the system level­ items are retrieved to the extent that there is a match between the representational systems are invoked at study and test. While Schacter's approach is comprehensive in its explanation of known phenomena, it is somewhat unparsimonious and may prove to be unfalsifiable.

1. 5 Repetition priming.

The psycholinguistic tradition offers another perspective on the conscious and unconscious representation of knowledge. A large number of studies have established that lexical decision and naming time generally decrease for words which have been processed previously within the experimental task, with the magnitude of the facilitation contingent upon the participant's awareness of the prior exposure.

This facilitation arising from prior processing within the task is termed repetition priming. Repetition priming is effectively an indirect memory measure, because the 'test' task (repetition of a classification task) is administered without reference to the 'study' task, and priming is frequently used as one of many possible measures of indirect memory. However, the origin of the repetition priming paradigm within the psycholinguistic tradition has resulted in a slightly different theoretical and operational perspective from

30 that offered by many memory theorists. Of particular relevance to the present

experiments is the extent to which lexical status (words vs. nonword) and word frequency allow direct investigation into the contributions of novelty and

relative familiarity to priming.

Three mechanisms underpinning repetition priming effects have been suggested, and it is possible that all or any of them may be relevant to performance in a given priming task.

Episodic contributions to repetition priming

Historically, the term "episodic memory" has had a phenomenological and an empirical definition, which are not always identical. When first proposed by Tulving (1972), episodic memory appears to have been intended to apply to the type of retrieval Jacoby & Dallas ( 1981) refer to as

'autobiographical'. Indeed, citing Reiff & Scheerer (1959, cited Tulving,

1972), Tulving regards " .. the experience of an "autobiographical index"" as the hallmark feature of episodic memory. Episodic memory was seen as

'date-stamped' information concerning specific life events.

The contrast between episodic and semantic memory was in terms of subjective access to the source of the knowledge. Semantic memory was knowledge held without specific recollection concerning the time and place of its acquisition. Episodic memory was information concerning specific events of personal history. Knowing the name of the capital of Italy requires semantic memory, recalling what you did yesterday, episodic. Episodic memory by this definition requires retrieval of the circumstances surrounding the acquisition of an item of knowledge.

31 Thus any aspect of repetition priming which involves retrieving the

previous encounter with the stimulus as the basis for the present response

can be identified with "episodic memory" in this narrow phenomenological sense.

However, an alternative, and more inclusive, definition of 'episodic' has gained acceptance within the literature. This definition does not concern itself with the subjective experience of the rememberer, focussing instead on the specifiable attributes of the retrieved material. Regardless of the participant's current awareness of a previous encounter with the item,

'episodic' memory in this sense is demonstrated wherever the retrieved material can be demonstrated to be integrated with the specific encoding episode. Under this very broad definition, retrieval has an episodic component wherever it can be shown to be sensitive to the specific features of the prior encounter. Insofar as aspects of retrieval can be directly indexed to a specific instance of learning, a form of episodic memory can be demonstrated.

For most descriptive purposes, the distinction between these two types of 'episodic' memory is immaterial. Most phenomenologically 'date­ stamped' information also shows specificity to the encoding conditions, and thereby yields instance-specific retrieval.

The distinction becomes crucial, however, when attempts are made to definitively separate 'episodic' from non-episodic components of priming.

'Phenomenal' and 'instance-specific' episodic memory

Priming may result from the strategic application of consciously

32 learned task-relevant information. The second time the item is encountered,

participants retrieve a phenomenological trace of their previous encounter,

and that recollection facilitates the second response.

There is little doubt that having a phenomenal episodic trace of the prime contributes to repetition priming effects. Under conditions in which participants are able to fully read and process the priming stimulus, many studies (Kolers 1976; Feustel, Shiffrin & Salasoo, 1983; Jacoby & Dallas,

1981; Bentin & Moscovitch, 1988) have obtained long lasting repetition effects for words persisting in the extreme case for up to 12 months (Kolers,

1976), although shorter periods of hours or days are more readily replicated.

Priming effects are also evident for nonlexical stimuli such as nonwords

(Scarborough, Cortese & Scarborough, 1977; Feustel et al, 1983) faces

(Bentin & Moscovitch, 1988), and geometric drawings (Schacter, Cooper &

Delaney, 1990), suggesting that this mechanism of priming is general across a range of stimulus classes.

Forster and Davis (1984) adopt the phenomenological definition of

'episodic' when describing the mechanisms serving repetition priming. This definition implies a requirement that participants are able to recall the encoding episode at the time of making their second lexical decision. A corollary of the phenomenological definition is a presumption that 'episodic' contributions can be reduced or eliminated if the subject cannot retrieve and/or process the original encoding episode. It is for this reason that Forster and Davis argue that backward masking of the prime minimises the episodic contribution to repetition priming

33 The phenomenal and instance-based interpretations of 'episodic

memory' differ in that the second account does not require conscious

awareness of the encoding episode at the time of retrieval. The nature and

extent of priming is, nonetheless, episode dependent. Specifically, the

'instance-based' episodic position holds that participants have learned about the stimulus and response and, even if the previous learning episode is not consciously available at recall, memory for the previous episode underlies the change in retrieval task performance. This approach incorporates the more inclusive definition of 'episodic', and is supported when the extent of priming is determined by the similarity of encoding and test episodes. In this sense, transfer-appropriate processing models (Morris, Bransford & Franks, 1977;

Roediger & Blaxton, 1987; Jacoby, 1983), which argue that retrieval is maximised insofar as there is an overlap information processing resources at study and test, also fall into this class of 'episodic' models.

Manipulations such as masking may eliminate the phenomenal experience of the prior exposure, without eliminating evidence of instance­ specific retrieval. Roediger & Blaxton (1987) obtained evidence for instance­ specific retrieval even when the priming presentation had been masked.

'Episodic' retrieval in the instance-specific sense need not, therefore, require conscious access to the encoding episode.

Much of the debate surrounding repetition priming centres upon the sufficiency of episodic accounts, and the extent to which any further mechanisms are required. Although episodic processes clearly contribute to priming, manipulations that reduce or eliminate conscious awareness of the

34 stimulus do not eliminate all repetition effects. When backward masking is

used to prevent subjective awareness of the prime, repetition priming is still obtained for words, albeit reduced in magnitude and of shorter duration.

This finding certainly weakens any argument for a fully phenomenal episodic explanation of priming, but of itself need not challenge accounts stated in terms of instance-based episodic mechanisms.

However, instance-based accounts do have difficulty explaining the dissociation with lexical status often found in masked repetition priming studies. Priming effects for nonwords are rarely obtained under masked conditions (Forster & Davis, 1984; Evett & Humphreys, 1981; Humphreys,

Evett, Quinlan & Besner, 1987). This is finding difficult to reconcile with an explanation of priming based entirely upon the acquisition of representations of new episodes. There is little a priori reason why a masked presentation of the string of letters "GROUND" should result in a more powerful episodic trace than the string of letters "GRONUD" unless one grants that the lexicality of the former delivers it some privileged status in the processing system.

However, there are many possible ways in which repeated exposure to single events can result in a form of 'abstraction' which is nonetheless a representation of episodes. The best known of these are models based upon a power-function acquisition of instances. Logan (1988) argues that with repeated processing instances, participants shift between applying an on-line response algorithm to retrieving specific learned instances. Using the analogy of a race, he argues that participants will base their response on whichever source yields a response sooner. As more instances are stored,

35 the greater the likelihood of the "memory" (instance-based) information

determining the response. As the likelihood of an instance being retrieved is

a function of number of prior instances, effects of lexicality and frequency can

be obtained without appealing to a distinct abstract representation.

Kirsner and Speelman (1993, 1996) present a modification of Logan's argument. In particular, they found that although repetition priming effects do generally conform to the power law, the relationship between practice within the experiment and the magnitude of repetition priming does not (Kirsner &

Speelman, 1996). Hence repetition priming may be an exception to the general power-function describing the relationship between practice and performance.

'Lexical' accounts of repetition priming.

The final class of explanations for repetition priming maintains that repetition priming reflects adjustment of the level of activation of an already learned representation of the item. This abstractionist view draws its metaphors from psycholinguistic models such as Morton's (1969) logogen framework. Priming arises when the residually activated logogen for a word is reactivated by the target stimulus. Forster (Forster & Davis 1984; Forster,

Davis, Schoknecht & Carter, 1987) refers to this as the 'lexical' component of priming, suggesting that it reflects short term changes in the state of activation of a logogen within a frequency-ordered lexicon. Without denying an important role of memory for specific episodes, abstractionist accounts ascribe all or most (see Tenpenny's (1990) distinction between 'pure' and

'weakly' abstractionist positions, below) of the repetition priming effect to

36 residual activation in abstract representations of words.

Differences in priming between words and nonwords, and the relative

insensitivity of word priming effects to surface feature changes, provide the

strongest evidence for abstractionist models (see below). Brown and Carr

(1993) conducted two detailed studies investigating the transfer of repetition priming across similar and different typefaces and tasks. Although task and typeface shifts produced specific interactions with priming effects, a large proportion of the facilitation could be attributed to lexical and semantic features of the items- a finding favouring a model which contains some form of abstract lexical component.

Mechanisms of repetition priming

There have been a number of alternative approaches taken to distinguishing between the classes models outlined above. The present, tripartite system (phenomenal episodic, instance-specific and lexical) emphasises the distinction between classes of episodic models and is perhaps less subtle in distinguishing between versions of 'lexical' approaches.

Tenpenny (1995) provides a different characterisation of models accounting for repetition priming, although emphasising similar aspects of the research. She distinguishes between 'pure' and 'weaker' versions of the episodic and abstractionist accounts.

Tenpenny's 'pure episodic' accounts attribute repetition priming entirely to mechanisms reflecting the recency and availability of specific prior occurrences of the item. Of those reviewed above, the views of Jacoby

(1983), and Logan (1988, 1990) are included in this category.

37 Weakly episodic accounts of repetition effects assert that, although generalisation across episodes may occur, a common form of representation applies to both individual episodes and generalisations. Although both abstract and episodic features of words may be extracted and utilised they derive from a common, episode-based representation. Tenpenny characterises distributed models of memory (e.g. McClelland and

Rummelhart, 1985) as falling into this weakly episodic category. Over repeated training trials, a network develops both a representation of specific inputs and a representation of general properties of those inputs. However, these representations are based upon aggregated instances, and are in this sense 'episodic'. The weakly episodic account allows for the emergence of abstract representations of word, while maintaining that nothing but episodic information has been retained and utilised.

The 'pure abstractionist' position (Tenpenny, 1995) is marked by the claim that word identification may give rise to a representation of the specific episode, but this representation is irrelevant to the word identification task.

The account is 'pure' in that there is believed to be no contribution of episodic components to lexical identification. Each exposure to a word activates its lexical entry, and that entry does not record any material specific to the particular exposure (e.g. Morton, 1979).

The view characterised by Tenpenny (1995) as 'weakly abstractionist' does not exclude a role for episodic components, but nonetheless suggests that word identification is based upon activation of abstract representations.

Thus episodic information can facilitate lexical identification, but the

38 contribution of this information is over and above the contribution from activation-based processes. Brown and Carr (1993) explicitly describe their model as 'weakly abstractionist' as it accommodates episode-specific representations while nonetheless asserting that cross-task priming effects demand an abstract semantic representation of words. Forster's claim that there are , both abstract and episodic contributions to different aspects of the priming effect (e.g. Forster & Davis, 1984; Forster, Booker, Schacter & Davis,

1990), would also be placed in this category.

Clearly there is overlap between weakly episodic and weakly abstractionist models within Tenpenny's classification. Both 'permit' both

'abstract' and 'episodic' information to influence repetition priming, and both accommodate a dual representation of each encounter with a word- it can be represented as both an instance and an alteration to the activation of the abstract 'lexical' entry. The distinction is one of emphasis and presumed origin. A core assumption of the weakly abstractionist view is that there must be a distinctively abstract representation of a known word, whereas the weakly episodic position holds that there may be a form of abstract representation, but it derives entirely from aggregated episodes.

Bowers (1994) proposed a distinction between acquisition and modification theories of repetition priming, by which the pure and weakly episodic explanations- which propose that the subject has learned how to

'deal with' a given item in a given situation as a result of previous experience within this task - represent acquisition theories. As 'lexical' approaches emphasise the adjustment of the level of activation of a pre-existing

39 representation, Bowers (1994) labels them as modification theories.

Theoretical distinctions between possible mechanisms contributing to repetition priming such as those outlined above have resulted in potent demonstrations of the nonunitary nature of repetition priming effects. The phenomenal episodic, instance-specific, and lexical interpretations of repetition priming effects give rise to differential predictions concerning the effects of word frequency and lexical status, and these literatures will be reviewed in turn.

Word frequency effects.

Word frequency has well-described and replicated influence on repetition priming. In unprimed conditions, high frequency words are endorsed more quickly and more accurately than low frequency words

(Scarborough, Cortese and Scarborough, 1977, Forster & Davis, 1984,

Ducheck & Neely, 1989).

However, low frequency words often show a greater benefit from repetition than their high frequency counterparts, resulting in an attenuated frequency effect following repetition priming. Forster and Davis (1984) found that this frequency attenuation effect was virtually eliminated if the priming trial was masked, suggesting that the frequency attenuation effect relies upon conscious awareness of the priming trial. As masking eliminated the frequency attenuation effect, but not the frequency effect itself, it was argued that word frequency is represented in the lexical system, which is independent of the 'episodic' system' (see below) that supports the frequency attenuation effect.

40 This association between direct retrieval and frequency attenuation in

repetition priming was explored further by Rajaram and Neely (1992). They

argued that if a common mechanism is active in both the frequency

attenuation effect and direct retrieval, the typical low frequency superiority in

recognition should be seen under the same conditions as those producing frequency attenuation in priming. While replicating the frequency effect and obtaining significant frequency attenuation for unmasked but not masked words (Experiment 2), they did not obtain the anticipated results in recognition memory.

Indeed, under incidental learning conditions, Rajaram and Neely

(1992) obtained a reversal of the typical low frequency superiority. Their results failed to verify the prediction that explicit memory mediates both frequency attenuation and low frequency superiority in recognition.

Furthermore, their results highlight a further twist in the explanation of frequency effects in priming, suggesting that the application of intention to

Jearn at the time of study also mediates the nature of retrieval of low frequency words. The relationship between word frequency effects, frequency attenuation and recognition memory remains unclear. Experiments

5 and 6 (Chapter 5) use direct and indirect memory measures to provide further insight into the roles of word frequency and repetition in recognition memory.

41 Nonword repetition priming

Nonwords have no prior status within the memory system. As such they provide a critical test of the extent to which repetition priming relies upon the participant having had prior experience with the stimulus item. A critical test of the distinction between instance-specif!c and modification approaches is the extent to which repetition effects are found for items with which the participant has no pre-experimental experience. An item that is not represented in memory cannot be activated, but it can form the basis of a newly acquired memory trace. For this reason, much attention has focused upon the occurrence and nature of repetition priming effects for nonwords.

If the 'unconscious' trace subserving repetition priming is essentially an implicit memory trace acquired through previous experimental exposure to the stimulus, it should show the characteristics demonstrated elsewhere in the literature for this type of memory. Repetition priming effects for nonwords should therefore be unaffected by levels of processing, disrupted by context and modality changes and preserved in amnesics, as reviewed in Chapter 1.

If, however, repetition priming effects require that the participant has a pre-experimental representation of the stimulus which is activated by the initial encounter, then nonwords should not show repetition priming, and repetition priming for words should show little dependence upon the particular experimental context in which the word was first presented. Essentially, any finding suggesting that words and nonwords show similar patterns of priming tends to favour episode-based theories. Any finding suggesting that

42 previously learned stimuli such as words show repetition effects not evident for nonwords tends to support modification based approaches.

There is no unequivocal evidence for either position. Many authors

(Kirsner & Smith, 1974; Carr, Brown & Charalambous, 1989; Whittlesea &

Cantwill, 1987) have found robust repetition effects for nonwords, often of similar magnitude to those obtained for words. However, nonword repetition effects have proven fleeting and highly task-bound. For example, they are rarely obtained in the lexical decision task- a paradigm which yields reliable and significant repetition priming for words (eg Forbach, Stanners &

Hocchaus, 1974; Feustel, Shiffrin & Salasoo, 1983). Nonword priming appears to be dependent upon the nature of the response required for the repeated presentation. Facilitation typically occurs only when the same response is required for all presentations (Tenpenny, 1995; McKoon &

Ratcliff, 1979).

While the fragility of nonword priming might be seen as favouring abstractionist or modification accounts, many authors have found that repetition priming for words is highly susceptible to apparently minor alterations in the form of stimulus presentation, such as modality of presentation (Kirsner, Milech & Standen, 1983; Graf et al. 1985) typeface

(Scarborough et al, 1977, Roediger & Blaxton, 1987) or orientation (Kolers,

1976). Such results are difficult to reconcile with an abstract, episode­ independent representation of the item.

Studies investigating repetition priming in amnesic populations have produced similarly inconsistent evidence. Early results suggested that

43 amnesics show repetition effects for words but not for pseudowords (Cermak,

Talbot, Chandler and Wolbarst, 1985), apparently supporting the view that

pre-experimental acquisition is vital to priming. However, more recent findings have demonstrated significant repetition priming for nonwords in amnesic populations (Smith & Oscar-Berman 1990; Haist, Musen & Squire,

1991; Cave & Squire, 1992).

Although amnesic patient studies seem to offer the greatest promise of resolving these contradictions, it is difficult to adjudicate between competing findings. 'Amnesia' is a broad term, covering a range of disorders and aetiologies, and patients with relatively consistent neurological disorders may differ markedly in the nature and severity of their memory dysfunction

(Schacter, 1990).

Thus, despite the accumulation of considerable evidence regarding the correlates of repetition priming, its precise theoretical .interpretation remains a matter of debate. This ambiguity arises, in part, from problems involved in comparing across multiple different memory tasks, conditions and patient groups. For example, the equivocality of the evidence regarding repetition priming effects for nonwords in normal and amnesic populations may reflect differences between the mechanisms contributing to repetition priming in different task contexts.

1. 6 Single process models

Although both the memory and the psycholinguistic literatures tend to emphasise dissociations between systems, processes or mechanisms, an alternative approach is to attempt to identify and elaborate the elemental 44 properties underpinning all memory performance. If a single series of

principles can be described which account for phenomena such as the direct/indirect distinction, word frequency effects and repetition phenomena, the argument for duplication of processes becomes considerably weaker.

Such unitary models tend to be computational descriptions of the parameters and algorithms serving memory which are then used as the basis for predictive models of established phenomena.

For example, the SAM (search of associative memory) model

(Raajimakers & Shiffrin, 1980, 1981; Gillund & Shiffrin, 1984) has parameters representing the associative strength between items held in memory and retrieval cues for those items, the association between different stored items, and the association between a learned item and its context. The multiplication of each of these strengths represents the overall strength of the association between a studied item, unstudied items, and the retrieval cues and contexts.

The model is a unitary model because it assumes that at retrieval the test cue is compared to all items stored in memory, and that this comparison determines the overall familiarity of this items in this context with this cue, which forms the sole basis of responding. When familiarity exceeds a criterion, a positive response is made.

The REM Model

Shiffrin and Steyvers (1997) develop a related unitary model called

REM (Retrieving Effectively from Memory) which amplifies and extends the parameters of SAM and other unitary models (eg MINERVA, Hintzman,

45 1988). The model differs from SAM because rather than parameters reflecting the associative strength between items, cues and contexts, the stored representation in REM is a richer vector of feature values.

An item about which nothing is known has a feature value of zero. As knowledge is acquired about an item, specific feature values within the vector increase. The size of the increase is partially determined by the base rate distribution of the feature, and the rate of increase is influenced by study time.

During study, the vector is sampled, and a direct copy of the sampled vector is stored. As both the likelihood of a feature value being true to the stimulus and the likelihood of a representative sample of the vector being taken increases with the availability of the stimulus,· a trace is more likely to be stored accurately as study time increases. At test, a probe vector is provided, which will have feature values which match and mismatch stored features of the studied vector to a greater or lesser degree. A matching algorithm is then applied. This computes a likelihood ratio by dividing the probability that the present probe vector would be observed if the study image had been the same by the probability if it had been different.

Thus, like the SAM model, the REM model depicts familiarity as the outcome of a calculation of the probability that the observed item is old, and as the single basis for a retrieval decision:

... the system uses Bayes' rule to calculate the probability that the test word was 'old' (ie. represented in the set of activated images), as opposed to 'new'. It is assumed that the calculated probability (or odds) corresponds to the feeling of 'familiarity' of an item and is used to produce a recognition decision. (Shiffrin & Steyvers, 1997, p147)

46 Counter Model

Ratcliff & McKeon (1997) present a model which, although quite differently conceptualised, operates in a manner similar to the REM model

(Shiffrin & Steyvers 1997). The counter model is essentially a model of response selection rather than memory processes. The Ratcliff and McKeon metaphor depicts the likelihood of selecting an item as old as a function of the number of 'counters' the response system has accrued for a specific probe in contrast with possible competitors. A decision is made when the count accumulated for one word exceeds the counts accumulated by others by some criteria! amount.

Similarly to the REM model, the counter model represents a stimulus as an array of features. Each word is represented by a single counter, which accumulates counts as a result of the overlap of features of the stored words and the presented item. As counters accumulate counts, they function as attractors, such that a counter which has accumulated many counts begins to draw counts away from counters representing similar words. This feature of the model allows it to explain the Ratcliff, McKeon & Verwoerd (1989, also

Ratcliff, Allbritton & McKeon, 1997) finding that forced-choice selection of old items is more accurate when the targets are similar to each other than when they are dissimilar, as well as a number of well established repetition phenomena.

Within the counter model, word frequency is represented as differential initial (pre-experimental) values of counts within the system, while the effects of prior exposure influence the attractor strength of the word, and

47 hence its ability to accrue further counts. Thus:

In the counter model, repetition effects are decoupled from word­ frequency effects such that study does not affect the components of the model that deal with word frequency. (Ratcliff & McKeon, 1997, p336)

1. 7 Connectionist approaches.

Connectionist models of memory (e.g. Mclelland & Rumelhart, 1985;

Seidenberg & McClelland, 1989) are based upon the premise that with repeated learning trials, connection weights between nodes are incrementally adjusted in order to maximise the likelihood of a correct output. When a trained network is re-exposed to an old item, it will reestablish the pattern of activation corresponding to that word.

The distributed nature of the ensuing representation makes it difficult to adequately characterise these models in the terms outlined above.

Tenpenny (1995) locates connectionist models of priming within the 'weakly episodic' group, insofar as any 'abstraction' which may arise results purely from the agglomeration of training episodes. In contrast, Bowers (1994) focuses upon the fact that training episodes result in adjustment of the connection weights within an established network, and therefore regards connectionist models as 'modification' views - suggesting they have more in common with abstractionist theories.

Connectionist models are both 'episodic' and 'lexical' in nature. All

48 acquisition is based upon repeated instances, and yet in time these come to be 'abstractly' represented. Rueckl (1990) suggests that this and other features of connectionist models, such as the ability to map across orthographic and lexical representations of words and the need for many learning trials lends validity to the suggestion that they may ultimately provide a useful model for human language skills.

, However, the extent to which a given network is capable of extracting general attributes of stimuli (eg lexicality) will depend upon the specific architecture of the model, the size of the training vocabulary, the nature of the input and output coding, and the number of training episodes to which it has been exposed. Hence despite the appeal of connectionist models as metaphors for human and animal cognition, it is not yet clear how much they might inform, rather than merely illustrate established theoretical positions. As

Forster (1994) observes, simulation is not explanation.

1. 11 The present experiments

The origin and nature of the subjective experience that an item is familiar, and the use of that experience as the basis for response selection, is a fundamental theme of the experiments described in this thesis. As outlined above, retrieval may be attributed to a range of conscious episodic, instance­ specific or abstract representations, with familiarity a component of some or all of these processes. Familiarity itself may also have several components.

The experiments which follow investigate the role of masking, repeated presentation and r~sponse execution on repetition priming and retrieval. A range of different operationalisations of 'familiarity' are used in order to

49 identify common contributions to familiarity from several theoretical perspectives and experimental paradigms.

In Experiments 1 and 2, participants are directly asked about the familiarity of backward masked items.

Experiments 3 to 6 extend the repetition priming paradigm and disentangle multiple possible mechanisms contributing to the retrieval of repeated words. The number and nature of responses to repeated items is manipulated for high and low frequency words and nonwords. Thus the effects of both pre-and intra-experimental familiarity of items can be distinguished and their influence on a common dependent measure can be systematically investigated. In Experiments 5 and 6, process dissociation procedures (Jacoby, 1991) are applied to estimate the relative contribution of familiarity and recollection- based processes to memory for repeated words and nonwords tested under the same conditions as those in Experiments 2 and 3.

50 Chapter 2: Experiments 1 and 2

2. 1 Familiarity and recognition failure.

Experimental demonstrations of memory without awareness typically rely upon two criteria being satisfied. Participants must be shown to have no awareness of the stimulus item, and they must show specific evidence of having processed the item (although see Reingold and Merikle 1988, 1990 for description of a differential sensitivity paradigm that does not require null awareness). As outlined in Chapter 1, the usual methodological approach involves establishing a 'threshold' for awareness and presenting items in the information processing task below that threshold.

Chance performance in a forced-choice recognition task has also been used as an index of the lack of awareness at the time of retrieval that the stimulus occurred in the study Jist (Kunst-Wilson and Zajonc, 1980,

Mandler et al. 1987). The use of null recognition as an index of a lack of conscious awareness presumes that participants will only guess if they have no other grounds on which to make a distinction between the presented items. However, implicit in this argument is that recognition decisions can be based only upon conscious recollection of the encoding event. Mandler

(1980) has suggested that familiarity may form the basis of recognition judgements for poorly remembered items, while Jacoby (1991) has also argued that recognition task performance will always reflect a combination of conscious recollection and a subjective sense of familiarity.

As reviewed in the previous chapter, Mandler, et al. (1987) attribute their findings that old items are selected above chance even when they

51 cannot be recognised to nonspecific effects of familiarity in the absence of recognition. However participants consistently failed to select the item they were shown under direct recognition instructions.

While much discussion has centred upon the above chance selection of old items on the basis of evaluative judgements, it can be argued that the exceptional result from the above is the failure to select old items in the recognition task. Given that the previously exposed item is selected more often than not on the basis of preference, brightness and apparent size, it is not clear why participants would systematically fail to select the old item on the basis of familiarity in the recognition task. Mandler et al (1987) suggest that chance recognition performance may be an artefact of the instructions typically used, which contain an implied expectation that participants will not recognise that stimulus. They report briefly upon a study in which the instructions were manipulated so that there was no implied expectation that recognition would fail. This more liberal recognition condition yielded above chance recognition performance. Similarly, Bonanno and Stillings' (1986) general instructions explicitly informed participants that they were unlikely to be able to recognise the item they were shown. They found that the use of a direct familiarity question (asking which of the two items is more familiar) yielded the same results as aesthetic preference judgements.

However the instruction that participants were unlikely to recognise the item may have introduced a possible confound. Participants were told that they would probably have difficulty determining which items had been presented previously and in this circumstance they should choose the more

52 familiar. These instructions explicitly identify familiarity and recognition as alternative bases for responding. They also imply that familiarity responses can and should be made on the basis of a 'weaker' memory experience than recognition judgements. These instructions may well lead participants to dichotomise the bases of their responses in a manner which echoes

Mandler's (1980) dual process theory. They are to treat familiarity and recognition as two types of evidence that an item is old, and to rely upon familiarity only under those conditions where recognition fails.

One of the goals of experiments 1 and 2 is demonstrate familiarity­ based responding in the absence of recognition under conditions that reduce any performance demands that may have been present in the instructions used for previous studies. No presumption is made as to how participants make their responses, and the instructions do not contain any expectation as to how response choices should be made. In separate retrieval tasks, participants are directly instructed to choose the more familiar item or the item they recognise. In the 'familiarity' task, participants are encouraged to respond to the more familiar item regardless of whether they recognise it from the prior exposure, while in the recognition task they are encouraged to guess when uncertain. The use of two-alternative forced choice procedures and counterbalanced critical and distractor lists permits the identification and estimation of systematic criterion effects or biases.

Repetition. familiarity and recognition

The experiments were designed to test the influence of repetition on the familiarity- and recognition- based selection of previously presented

53 words. Granting Mandler's (1980) argument that integration/activation arises through exposure to the stimulus, and that the sense of familiarity arises through activation, repeated exposure, at least over the short term, should increase the familiarity of the stimulus. The probability of selecting the old item in a forced choice task should therefore increase if the item has been presented more frequently.

However, this prediction appears inconsistent with Marcel's (1983a,

Experiment 5), finding that participants showed chance performance in a task requiring detection of a masked item despite up to twenty repetitions of the stimulus. This occurred even though there was clear evidence of accumulating activation as assessed indirectly through facilitation of lexical decision performance.

One solution to this apparent contradiction may lie in Marcel's selection of stimulus detection as an index of conscious processing.

Elsewhere in the memory literature, detection or identification of stimuli under highly speeded conditions ('perceptual identification') is regarded as an indirect memory test (e.g. Richardson-Kiavehn & Bjork, 1988; Roediger,

1990). It has normally been shown to be influenced by similar variables to those influencing other indirect measures- such as recency of presentation, perceptual similarity and consistency of context. Marcels' 'dissociation' between detection and lexical decision facilitation is really a dissociation between two indirect memory tasks, whereas Mandler's distinction is between direct and indirect measures of memory. Hence the two findings need not be regarded as contradictory, but rather as reflecting the authors' slightly

54 different typologies of memory and conscious experience. Nonetheless, the apparent failure of items to accrue sufficient activation to become available to detection despite many presentations appears incompatible with Mandler's

(1980) view that familiarity accrues from repeated exposure, and is perhaps more consistent with Marcel's (1983b) suggestion of parallel and independent systems.

Experiments 1 and 2 combine a comparison of the familiarity and recognition-based retrieval tasks used by Mandler with the masked repetition paradigm used by Marcel to provide a more specific test of the influence of repeated stimulus presentation on forced-choice recognition and familiarity judgements for familiar stimuli.

Words, rather than novel stimuli are used because the focus of the experiment is on the extent to which familiarity is accrued as a function of repetition. Repetition of masked words allows investigation of the influence of the increasing familiarity arising from repetition within an experimental session without the possible confound of the establishment of a representation of a novel stimulus item.

Mandler, et al. (1987) comment upon an unpublished study similar to the present Experiments 1 and 2, although little detail about the masking conditions is provided. While for unmasked briefly presented words, participants selected old items with above chance accuracy in the preference task, no effect at all was reported for the masked version of the same task.

They attributed their null findings for masked stimuli to the integration of perceptual properties of the mask and stimulus at presentation. The

55 perceptual processing of the stimulus is disrupted by the onset of the mask, and the stimulus and the mask become an integrated perceptual unit, thereby preventing any activation of the stimulus

The extent to which masking disrupts the formation of an initial percept rather than cognitive processing has been the subject of substantial prior research. Turvey (1973) distinguished 'central' from 'peripheral' masking, on a number of procedural and empirical grounds. According to Turvey peripheral masking disrupts the initial perceptual processing of the stimulus by fusing with the stimulus properties itself. Central masking, by contrast, disrupts the ongoing processing of the stimulus, is effective when binocularly presented, and is maximised when a pattern mask is used. In the present experiments and all of those reviewed above, the procedures are best classified central masking.

As reviewed above, there is evidence that semantic and perceptual analysis of words can proceed where masking eliminates conscious access to the item. Briefly presented masked words appear to significantly impact upon the processing of later, nonmasked targets, producing semantic (Marcel,

1983a) and repetition (Forster and Davis ,1984) priming effects.

These experiments combine the methodologies of Marcel (1983) with those of Mandler et at. (1987) and Bonanno and Stillings (1986) in order to clarify apparent inconsistencies between those studies, in particular the impact of repetition of masked familiar words upon recognition memory performance.

In Experiments 1 and 2, masked words were presented once or

56 repeated as many as ten times at exposure durations of 14 or 42 milliseconds. Participants then made two-alternative forced choice recognition and familiarity judgements about the presented item. In

Experiment 1, retrieval testing followed immediately after stimulus presentation. In Experiment 2, study and test phases were separated.

It is expected that exposure duration will interact with repetition and question type, yielding dissociations between the factors influencing retrieval of information presented for short and longer durations. In the absence of potentially biasing instructions, the prediction from Mandler et al. (1987) is that, under conditions of uncertainty, familiarity shall form the basis of recognition memory, producing an increase in both recognition and familiarity judgements of old items as a function of repetition. In contrast, if there are two independent processing systems as suggested by Marcel (1983a), masked words may accrue activation as evidenced by performance on another task without ever being detected or recognised.

2. 2 Preliminary study

A preliminary study (N=12) was conducted to determine optimal exposure durations and task instructions. Randomly selected words of between 4 and 8 letters were presented once, five or ten times at exposure durations of 14, 42 84 milliseconds. Following each item, participants were presented with a forced choice between the original item and a foil and asked to select an item in response to one of the three questions: Which did you see?, Which is more familiar?, and Which is more common?

57 Results:

The results were unexpected in the light of the above rationale, and are presented in Table. 1.

Table 1: Percent selection of old items, Preliminary Study : Exposure = exposure duration, Cue=response cue, presentations= number of presentations. Chance= 50% Exposure Cue Presentations Duration 1 5 10 14 Recognise 64.29 61.37 49.74 milliseconds Familiar 71.20 59.80 39.33 Common 64.18 48.69 40.60 42 Recognise 67.23 73.12 73.37 milliseconds Familiar 71.20 68.80 76.36 Common 51.18 61.92 70.60 84 Recognise 82.96 86.52 87.90 milliseconds Familiar 73.21 79.13 89.33 Common 64.07 67.35 73.47

The frequency estimation question (Which is more common?) consistently yielded the lowest level of selection of old items, yielding a significant main effect for question type [F (2,22) = 4.41]. Likelihood of selection of an old item increased as a function of increasing exposure duration [F(2,22) =12.77]. The main effect for number of presentations was not significant.

58 A significant interaction was obtained between number of repetitions and duration [F(2,22) = 9.37], with probability of selection of an old item increasing as a function of number of presentations for the 42 and 84 millisecond presentations, but decreasing as the number of presentations increased in the 14 milliseconds condition.

Although the difference between the frequency judgement question and both recognition and familiarity was consistent across conditions, the familiarity and recognition questions can be seen in Table 1 to converge as a function of increasing repetition numbers for the 42 and 84 milliseconds presentation, but to diverge at 14 milliseconds. Sample size restricted the extent to which this apparent partial 3-way interaction could be meaningfully explored, but it became a focus of Experiment 1.

The preliminary study suggested that restricting exposure duration produces a dissociation in both direct familiarity and recognition memory performance as a function of number of repetitions. While repetition was associated with an increased probability of selection of old items in both tasks at 42 and 84 millisecond exposures, probability of retrieval in both tasks appeared to decline as the number of 14 milliseconds repetitions increased, suggesting inhibitory repetition priming.

The study also included a forced choice judgement of word frequency

(Which is more common?). This appeared to be a weak parallel of the familiarity task, being influenced in the same way as that task by each of the experimental manipulations. Only the recognition and familiarity judgements are included in Experiment 1. Similarly, the preliminary study included an 84

59 millisecond exposure condition. As all significant interactions with exposure duration discriminated the 14 millisecond exposure from both 42 and 84, only the 14 and 42 millisecond conditions are used in Experiment 1.

2. 3 Experiment 1

In Experiment 1, participants were presented with a word for either 14 or 42 milliseconds which was then masked. Word/mask pairs were repeated in blocked series of 1,5, or 10 presentations. Shortly after the word display participants were presented with the original word and a new word and asked to indicate either which item was more familiar or which they had previously been shown, and to rate their confidence in the judgement they had just made on a 0-4 scale. The retrieval tasks were mixed in order to prevent the development of task-specific response strategies.

The confidence rating was included because it was felt that the absolute accuracy of the judgements might mask important differences in the subjective strength of the trace underpinning the response. An explicit rating of confidence may provide a more sensitive measure of differences between familiarity and recognition response that may not be reflected in absolute recognition accuracy.

The results of the preliminary experiment appeared to dissociate the

14 and 42 millisecond exposure durations in terms of their interactions with repetition and response cue. In particular, the 14 millisecond presentation appeared to result in an inhibition of the selection of old items, particularly in response to the direct familiarity cue. This is interesting in the light of the literature motivating the study, where the more usual result is that familiarity 60 (however assessed) accrues with repetition of masked items. While the preliminary study was intended to test between specific predictions of

Mandler (Mandler et al, 1987) and Marcel (1983A) regarding the basis of recognition judgements for masked item, it yielded inhibition of selection of old masked items with repetition, a finding inconsistent with both approaches.

Experiment 1 is a more focussed replication of the key procedural elements of the preliminary study, with the same theoretical derivation.

Method.

Design: A 2 (question type) X 2 (exposure duration) X 3 (1,5,10 repetition) repeated measures design was adopted. Word list (2) is a between-subject variable

Participants. 30 undergraduate students at the University of New

South Wales participated in the study for course credit. All had spoken

English predominantly for at least ten years.

Materials: 240 nouns were selected from the MRC Psycholinguistic database (Coltheart 1981) according to the following criteria: Word length of

4-8 letters, no more than two syllables and frequency between 20 and 40 per million (Kucera and Francis). See Appendix A. A pattern mask was generated from the #, @ and & characters.

These words were ranked by frequency and divided in an odd-even fashion into two lists of 120. Half the participants studied list A and half list B.

Ten words from each list were randomly assigned to the 12 study conditions defined in the Design section.

Procedure. The experiment was run on a 286 PC under a two-monitor

61 DMASTR system and responses registered with a two-microswitch keypad. A footswitch was used to initiate the practice items and the main block.

Participants were given the following written instructions:

" This experiment is investigating memory for words presented

very briefly. You will see a row of# characters which will quickly be

replaced by another row of characters. A word will be presented

between the first and the second rows of characters, but that word will

not always be visible.

Immediately following the second set of characters, you will be

asked one of two questions and shown two words. You are to choose

the word that best answers the question. Press the button on the left if

the word on the left best answers the question ,and the button on the

right for the word on the right. In response to the question "Which did

you see ?" , choose the word that that was presented between the

rows of characters. In response to "Which is more familiar?" choose

the more familiar word, regardless of whether it had been presented.

You must answer each question, so if you are not sure, guess.

Immediately following your response to the question , you will

be asked to rate your confidence in your response to the question on a

0-4 scale where 0 corresponds to guessing , 2 is "fairly sure" and 4 is

"certain". There will be a practice run before the main experiment

starts. Are you ready?

Twelve practice trials were presented followed by the main stimulus set. Item choice and response latency were recorded automatically. The

62 vocal confidence judgement was recorded by the experimenter. Each item was initiated two seconds after the confidence rating for the previous item had been recorded.

Results.

Retrieval: The percentage of old items selected in Experiment 1 is shown in Table 2. No main effect was obtained for list [F(1 ,28) = 1.15, ns], so analyses have ignored the list factor.

Table 2. Experiment 1: Mean percentage of old items endorsed in recognition and familiarity tasks. Standard deviation in parentheses.

Exposure Retrieval Number of Presentations Duration Task 14 Milliseconds Recognition 1 5 10 50.67 52.00 50.67 (16.17) (13.99) (13.88) Familiarity 45.33 52.00 49.67 (16.96) (18.45) (16.91) 42 Milliseconds Recognition 65.67 63.00 77.67 (15.6) (20.54) (21.12) Familiarity 55.67 67.33 73.67 (21.92) (20.67) (20.25)

No effect was obtained for question type [F(1 ,28)= 2.64, ns].

Significant main effects for were obtained for exposure duration [F(1 ,28)=

35.46], with items presented for 42 millisecond more likely to be recognised than those presented for 14 milliseconds, and number of repetitions [F(1, 28)

= 6.97]. Analysis of the effect of repetition showed that there was no

63 significant difference in recall between one and five repetitions [F(1 .~8) =

2.87, ns], but average performance was significantly better under both question types following ten repetitions than following five [F 1,28)= 12.46].

The magnitude of the difference between one and five repetitions interacted with retrieval question [F(1 ,28= 10.02]. Selection of old items in response to the familiarity cue was greater after five than one presentations, but there was no change in response to the recognition cue.

Number of repetitions interacted significantly with exposure duration

[F(1 ,28)= 8.29], because the 42 millisecond exposure resulted in increasing reselection of old items between 5 and 10 repetitions, which was not found for the 14 milliseconds exposure.

The three way interaction between question type, duration and 1 vs 5 repetitions was significant [F(1 ,28)= 10.02], with recognition performance alone declining slightly between 1 and 5 presentations at 42 milliseconds.

To provide more detailed evidence about the differences between recognition and familiarity performance a series of comparisons revealed that items were significantly more likely to be recognised than endorsed as familiar after one presentation [F(1 ,28)= 6.68], but this difference was no longer significant by the fifth presentation [F< 1, both questions]. The difference between familiarity and recognition after a single exposure was significant at

42 milliseconds, [F(1,28) = 8.41], but not at 14 milliseconds [F(1,28) = 1.58, ns].

The retrieval data therefore suggest that for the 42 millisecond exposure, repetition increases both familiarity and recognition between five

64 and ten repetitions but familiarity alone between one and five presentations.

Furthermore, old items are less likely to be selected in response to the

'familiarity' than the recognition cue retrieval following one presentation, significantly so at 42 milliseconds. Thus the increasing forced-choice selection of old items as familiar as repetition increases reflects familiarity

'catching up' with the initially higher recognition-based retrieval rates.

As an alternative test of the independence of the "familiarity" and

"recognition" judgements, the correlation between these two variables was computed. The recognition and familiarity data were found to be highly significantly correlated (r =0.570, p< 0.01)

Confidence: Following each familiarity and recognition judgement, participants were required to make a 0-4 rating of confidence in their judgement about each item. Confidence ratings for the 12 conditions are given in Table 3.

Table 3. Experiment 1: Mean rated confidence (0-4) in retrieval accuracy from recognition and familiarity tasks. Standard deviation in parentheses. Exposure Retrieval Number of Presentations Duration Task 1 5 10 14 Milliseconds Recognition 0.207 0.340 0.407 (0.31) (0.42) (0.53) Familiarity 0.513 0.570 0.587 (0.756) (0.723) (0.73) 42 Milliseconds Recognition 0.793 1.513 1.743 (0.70) (1.08) (1.19) Familiarity 0.930 1.463 1.710 (0.81) (0.92) (1.12)

65 Many participants reported difficulty with this task, especially when they were required to make familiarity judgements. They were told initially to select the more familiar item regardless of whether or not it had been presented. As such, they felt it was impossible for them to find a basis for their confidence judgements. Those who raised these concerns were told to continue with the task as well as possible and given no further direction.

Presumably reflecting the participants' reported difficulties with the task, confidence ratings were low overall, with no condition mean exceeding the "fairly sure" rating of 2.00.

Participants were more confident in their judgements about stimuli presented for 42 than 14 milliseconds [F(1 ,28)= 35.55], and number of repetitions also increased confidence [F(1 ,28)= 34.61]. Question type did not significantly affect confidence judgement [F=1.35, ns].

The interaction between duration and repetitions was significant

[F(1 ,28)= 19.07], with repetitions increasing confidence for the 42 but not the

14 millisecond presentations. Duration also interacted with question type

[F(1 ,28) = 12.65], with participants reporting more confidence in their familiarity than their recognition judgements for the 14 but not the 42 milliseconds exposures.

Discussion.

Recognition of items presented for 14 milliseconds remained at around chance regardless of the number of repetitions of the stimulus.

Familiarity judgements increased as the number of repetitions increased, at

66 least between 1 and 5 repetitions and this was independent of the effects of repetition on recognition. Each of these findings is consistent with much of theoretical material reviewed in the introduction to this experiment, and inconsistent with the results of the preliminary study.

However, a crucial and unexpected finding was that the probability of endorsing an item in response to the familiarity cue was initially lower than that for recognition and never exceeded it. Hence Experiment 1 did not produce any evidence of familiarity in the absence of recognition.

Experiment 1 was intended to investigate the differences between familiarity and recognition- based judgements in the context of repeated masked words. The preliminary study had also suggested some form of inhibitory repetition priming effect for words repeated at 14 milliseconds, which warranted further examination.

There was no evidence of inhibitory repetition priming in the present study, although there was a nonsignificant trend for endorsement rates overall to decline between five and ten repetitions for the 14 but not the 42 milliseconds exposure. The theoretical and procedural implications of this result are discussed following Experiment 2.

2. 4 Experiment 2.

Experiment 1 provided equivocal evidence that if memory is tested immediately following stimulus presentation, singly presented items are more likely to be recognised than endorsed as familiar. There was no evidence of the inhibitory effects obtained in the preliminary study. While endorsement of old items as familiar did increase between one and five repetitions, response 67 to the 'familiarity' cue never exceeded recognition rates. As such, the present results for words are not consistent with the Bonanno and Stillings' (1986) findings for nonsense figures.

Experiment 2 was designed to extend the findings of Experiment 1.

Specifically, it was designed to test the duration of the recognition and familiarity effects suggested by that experiment. The principal difference between Experiments 1 and 2 is that in Experiment 2, the familiarity and recognition tasks are administered at the end of the masked repetition study task. Items were re-allocated to stimulus lists, but the same items and overall trial structure were utilised in Experiment 2 as Experiment 1.

Because the familiarity and recognition retrieval tasks did not immediately follow the final backward mask in each trial, but were instead administered in a subsequent test phase immediately following the study task, two further procedural changes were required. As participants were not being tested immediately following stimulus presentation, it was necessary to provide a rationale that ensured adequate attention during the study task.

After the final backward mask of each trial, participants were given the cue

"Anything?" and required to press the 'yes' button if they believed a word had been presented between the forward and backward masks, and the 'no' button if not. This requirement was felt to be compatible with the information that experiment concerned "memory for briefly presented words" as for

Experiment 1.

A second change implied by the shift from interleaving to separating study and test trials was to ensure that Experiment 2 remained an intentional

68 study task, such that participants were aware at the time of study that there would be a subsequent test. The constant provision of the retrieval cues in

Experiment 1 had ensured that participants were continually aware of the fact that memory was being tested. For Experiment 2, the instructions were modified to make more explicit that participants would later be asked to select familiar and remembered items, and that they should concentrate on the items they saw during the study task for a later test.

As described above, the confidence rating task was regarded by participants as difficult and ambiguous. Furthermore, the task yielded results which did not appear to add any further information than the familiarity or recognition tasks. It was therefore eliminated from Experiment 2.

These modifications make Experiment 2 more compatible with the methodologies of Kunst-Wilson and Zajonc (1980) and Mandler et at (1987), although dissimilar to that used by Marcel (1983A), who interleaved study and test task in a manner similar to that in Experiment 1.

Method.

Participants: Fifteen undergraduate student participated in the study for course credit. All had normal or corrected vision and had spoken English predominantly for at least five years.

Apparatus: Word lists: The word list used in Experiment 1 (Appendix

A) was randomly re-allocated into two stimulus lists. The Experiment was run using a two-monitor DMASTR system under the control of an industry­ standard 286PC.

Procedure: Participants were told that they were participating in a

69 study investigating memory for briefly presented words. They were given written instructions outlining the procedure. Participants were then given 12 practice trials followed by the main block. As in Experiment 1, items were randomly presented for 14 or 42 milliseconds followed by a backward mask, with 1,5 or 10 massed presentations of the stimulus in each trial. Immediately after the offset of the final mask, they were cued to indicate whether or not they had perceived any words during the masking sequence. The next item followed 2 seconds after their response to the detection cue.

After all 120 items had been presented, participants were given the following instructions for the memory task:

"You will be asked one of two questions and shown two words. Press the button on the left if the word on the left better answers the question, and the button on the right for the word on the right. In response to the question "Which did you see ?", choose the word that that was presented in the previous task. In response to "Which is more familiar?", choose the more familiar word, regardless of whether it had been presented. You must answer each question, so if you are not sure, guess." All 120 items were the randomly represented in a 2-alternative forced choice detection task paired with items from the nonstudied list. Familiarity and recognition cues were mixed as in Experiment 1.

Results.

Detection: Stimulus detection was not intended as an index of conscious awareness of the stimulus, and the task was included only to ensure adequate attention during the encoding tasks. Preliminary investigation of the data revealed that nine of the 15 participants had recorded reaction times of 0 milliseconds for the majority of items in the

70 detection task. This suggests that they had initiated their response at some point during the course of the trial prior to the "Anything?" request which started the timer. The detection data cannot, therefore, be meaningfully interpreted

Retrieval: Table 4 summarises the probability of retrieval of old items in response to the recognition and familiarity questions in Experiment 2.

Overall, recognition performance was at or around chance for all conditions.

No significant main effects were observed [All Fs < 1.15, ns].

Question interacted with number of repetitions between one and five presentations [F(1, 13) =5.28], but not between five and ten presentations.

Selection of old items in response to the familiarity cue increased between 1 and 5 presentations, whereas recognition accuracy decreased over the same interval. The 10 percent decrease in accuracy for the recognition question between 1 and 5 presentations for the 42 milliseconds exposure was not significant [F(1, 13)= 3.92, ns]. The endorsement of old items as 'familiar' increased between 1 and 5 repetitions for the 14, but not the 42 millisecond exposures [F(1, 13) = 5.87, and F<1 respectively].

71 Table 4. Experiment 2: percentage of old items endorsed in recognition and familiarity tasks. Standard deviation in parentheses.

Exposure Retrieval Number of Presentations Duration Task 1 5 10 14 Milliseconds Recognition 54.67 51.33 50.67 (15.05) (20.31) (14.86) Familiarity 40.67 50.00 49.33 (16.24) (16.03) (18.30) 42 Milliseconds Recognition 52.67 42.00 50.67 (19.80) (16.56) (12.22) Familiarity 46.00 49.33 48.67 (15.02) (15.33) (19.22)

For both exposure durations, old items were more likely to be endorsed after one presentation in the recognition than the familiarity judgement [F(1, 13= 5.92], with the retrieval questions converging by the fifth presentation.

As for Experiment 1, computation of the correlation coefficient revealed a relationship between the 'familiarity' and 'recognition' responses which, although lower than for the previous study, was still significant (R=

0.223, p<0.05)

Experiment 2 therefore partially replicated the findings of Experiment

1 for briefly exposed masked words assessed followed by direct familiarity and recognition questions. Repetition of masked words is more likely to result in an increase in selection of the items as 'familiar' than as recognised.

72 Selection of old items on the basis of familiarity is, however, initially below

recognition performance. It increases between one and five presentations to about the same level as recognition performance.

Two key differences between the results of Experiments 1 and 2 are that in the initial study, words presented for 42 milliseconds were selected with well above chance accuracy for both retrieval cues, while in Experiment

2, endorsement of old items remained at about chance. Secondly, Experiment

2 suggested some inhibition of recognition responses for the briefer exposure duration between 1 and 5 presentations, albeit nonsignificant.

Discussion. Experiments 1 and 2.

Four conclusions can be drawn from Experiments 1 and 2. First, between 1 and 5 repetitions, there was an incremental likelihood of selecting old items as more familiar, but no corresponding increase in recognition accuracy, indeed accuracy decreased slightly in Experiment 2. Second, after a single exposure, participants were more likely to select an old item as recognised than as familiar; a finding which obtained whether tested immediately following stimulus presentation (Experiment 1) or after a delay of approximately ten minutes (Experiment 2). Third, when exposure and retrieval testing were separated (Experiment 2) memory performance overall remained around chance whereas items presented for 42 milliseconds were easily retrieved when study and test were interleaved. Finally, although the

'familiarity' and 'recognition' responses demonstrated differential sensitivity to exposure duration and repetition variables, they covaried significantly in each experiment, undermining claims that they form independent grounds for the

73 selection of previously encountered items. Each of these findings warrants interpretation in the light of the theoretical material reviewed in the introduction to the Experiments.

Familiarity accrues with repetition

The finding that selection of old items in response to the 'familiarity' cue increased with the number of exposures to the stimulus (between 1 and

5) is consistent with Bonanno & Stillings' (1986) findings. They attributed familiarity-based responding to perceptual fluency (Jacoby and Dallas, 1981) processes. Fluency arises from 'practice' at processing the stimulus, and is therefore enhanced as a function of the number of occasions on which the stimulus has been processed, especially if the structural and contextual features remain consistent across occasions, as they do in the present repetition conditions.

However, if participants' responses to the cue 'which is more familiar?' are indeed a reliable index of the psychological construct

'familiarity', which in turn reflects fluency, then the second of the general findings from Experiments 1 and 2 becomes difficult to explain. It is not clear how, in a two-choice task, an item could be recognised without being familiar, as would appear to be the case for masked items presented only once.

Recognition does not require familiarity

Studies conducted within various dual process frameworks have suggested that, under a number of conditions in which recognition performance is around chance, familiarity based judgements remain above

74 chance. Even experiments which fail to replicate this finding (eg, Mandler, et al., 1987), have yielded chance performance on both familiarity and recognition tasks. The present finding, replicated in both experiments, that familiarity is initially below recognition, is not consistent with either of these results. They are also inconsistent with the results of the preliminary study conducted prior to Experiment 1, where the familiarity cue reliably yielded greater likelihood of selection of old items after one exposure than the recognition cue.

Within Mandler's (1980) dual process model, familiarity (in this case identified with activation/elaboration) is a necessary precursor to recognition.

Mandler, Hamson and Dorfman (1990) highlight the relationship between activation and elaboration within their dual-process model (eg Mandler 1980):

The subjective recognition experience of mere

familiarity may be produced in the absence of semantic/search

processes; in order to identify what the event is or where or

when it has been encountered, prior elaboration is necessary.

(Mandler, Hamson & Dorfman, 1990, p714)

Hence 'mere' familiarity provides the foundation from which recognition is possible, but elaboration is required for before a recognition judgement can be made. However, this explanation provides no account of recognition in the absence of familiarity, as suggested by the present data.

Jacoby's (1991) variant of the dual process model, especially as instantiated in his more recent 'process dissociation' (PO) methodology,

(reviewed in Chapter 4) does not make the same strong presumption that

75 recognition must always include a contribution from familiarity-based processes. However, it is important to note that Jacoby's argument is based upon a specific set of procedural and conceptual principles which were not complied with in Experiments 1 and 2. The process dissociation procedures, assumptions and alternative models are described and utilised in

Experiments 5 and 6 (Chapter 5).

Experiments 1 and 2 were designed partially in response to the argument outlined above regarding the instructions used by Bonanno and

Stillings (1986). It was suggested that they 'instructed' participants to regard familiarity and recognition as alternative bases for an 'old' response, and that their results may partially have reflected demand effects arising from that instruction. While not entirely contradicting the findings of the earlier study, the results of Experiments 1 and 2 do suggest that when no explicit instruction is given about how and when a 'familiarity' response should be made, the results are markedly different from those obtained when familiarity is presented as a secondary basis for responding. As argued later in this

Chapter, responding on the basis of 'familiarity' to an item which is both pre­ experimentally familiar (a known word) and familiar due to its prior presentation in the experiment may result in tension between these conflicting sources of familiarity. The results of Experiments 1 and 2 suggest that this conflict is exacerbated when little information is provided about the expected basis of a 'familiarity' response.

Chance performance in recognition and familiarity

Although the experiments did not explicitly inquire about participants'

76 conscious awareness of the masked stimulus, chance recognition performance has been taken elsewhere (e.g. Kunst-Wilson & Zajonc, 1980,

See Chapter 1) as an indicator of null awareness, especially when test immediately follows study (as in Experiment 1). This view implies that participants do not have immediate conscious access to items presented for

14 milliseconds in these experiments. Items presented for 42 milliseconds are clearly available for conscious processing, because retrieval remains above chance in all 42 milliseconds conditions in Experiment 1 where testing occurred immediately after stimulus offset. However, the delay between study and test in Experiment 2 appears to have eliminated any memory of this conscious processing.

Significant correlations between recognition and familiarity.

Figure 1 depicts the relationship between recognition accuracy and selection of old items as 'familiar" in the preliminary study and Experiments 1 and 2,.

The data points represent experimental conditions. The overall regression equation is highly significant (R2 = 0.833, F(1, 19)= 94.5, p<0.001), confirming the results reported in those experiments that the 'familiarity' and 'recognition' cues produced responses which were highly correlated.

77 30 40 50 60 70 80 90

FA MIL

Figure 1: Regression line and scattergram, recognition and familiarity, preliminary study and Experiments 1 and 2. Data points are conditions

This finding erodes the strength of any claim that this paradigm produces evidence of the independence of 'familiarity' and 'recognition' responses. It suggests that although the two cues produce responses which are differentially sensitive to manipulations of exposure duration and repetition, there is no evidence that they are accessing orthogonal memory representations in the manner suggested by many of the dual process models described in previous Chapters. While the differential sensitivity of the two cues to experimental manipulations does suggest that the tasks differ to some

78 extent, their high covariance indicates that they may be accessing the same construct. The difference between task dissociation and construct or process dissociation is outlined more fully in Chapter 4.

The procedures used to assess familiarity and recognition in the present experiments were somewhat different from those used in earlier relevant studies. It is possible that the results are an artefact of the somewhat unorthodox paradigm used. These procedures will be reviewed before discussing possible theoretical implications of the studies.

2. 5 The direct familiarity task

The use of the questions Which is more familiar? and Which did you see? to assess recognition and familiarity was derived from Bonnano and

Stillings (1986), who found that participants' responses to the question Which is more familiar ? appeared to be based upon the same trace as that serving preference judgements. This trace was different from that serving recognition judgements.

Bonanno and Stillings obtained two reliable dissociations between preference/familiarity and recognition. Firstly, although brief exposure durations produced chance recognition performance, old items were still selected on the basis of familiarity and preference. Secondly, recognition performance was influenced by manipulation of associations between context at study and test, while familiarity and preference judgements were not.

Bonnano and Stillings therefore argued that Which is more familiar ? accesses the same trace as that identified by preference, discriminative judgements and other indirect memory tests, which they identified with

79 'perceptual fluency' (Jacoby & Dallas, 1981 ).

Experiments 1 and 2 applied a similar procedure to already familiar stimuli (known words), and it was found - as anticipated, that familiarity but not recognition increased as a function of repetition of briefly presented masked stimuli, at least between one and five presentations. These results do suggest a robust dissociation between recognition and familiarity judgements, but they are inconsistent with those of Bonanno and Stillings because they do not show any evidence of familiarity-based processes in the absence of recognition memory. Indeed they suggest the opposite: if an item is presented once and masked, and memory for it tested using the question

"Which is more familiar?, activation of the remembered trace appears inhibited relative to recognition accuracy.

The results of Experiments 1 and 2 suggest, that, somewhat paradoxically, participants choose the less intra-experimentally familiar word, selecting the new foil in the 2 alternative forced choice task more often than the old item. This appears to be more likely to occur when no explicit instruction is given as to how to make a 'familiarity' judgement (in contrast with previous studies). There are 2 general classes of explanation which may account for this finding. It is possible that participants establish a response bias against the old item, or that the representation of the old item is itself inhibited at the time of retrieval. Each of these possibilities shall be reviewed.

80 2. 6 Theoretical implications: Experiment 1 and 2

Response bias

One account of below chance performance is to suggest a systematic bias against endorsing old items as more familiar in the single presentation conditions. However, several logical and empirical observations challenge this suggestion.

Logically, there appears to be little reason why participants would consistently adopt such an idiosyncratic bias. It would amount to a decision

(whether conscious or not) that, regardless of whether they could see the item, they would respond to the new word wherever it is presented with an old word that had been presented once only in the study task. The fact that this result emerges even more strongly in Experiment 2 suggests that they maintain this idiosyncratic bias for some time after the initial presentation of the item.

Empirically, the reason for including the confidence judgement in

Experiment 1 was to provide evidence for any systematic differences in the participants' subjective experience of the retrieval tasks in the different conditions. Insofar as the confidence results inform the above discussion about recognition superiority at one presentation, they do not strongly suggest specific bias against familiarity-based responding after one presentation.

However, by suggesting that participants are able to accurately monitor their retrieval performance in all conditions but the single exposure, the confidence data tend to favour any model which regards the familiarity 81 judgment after one exposure an exceptional finding requiring a unique explanation. Hence a general bias against familiarity-based responding is unlikely to be sufficient.

Inhibitory mechanisms

Another possible account of these findings derives from recent evidence implicating active, central inhibition of recently presented items in certain tasks. There is increasing evidence that inhibitory mechanisms

'dampen down' the level of retrievability of items represented in both short­ and long-term memory systems.

Anderson and Bjork (1995) propose a taxonomy of inhibitory mechanisms in an endeavour to provide a theoretical account of the 'retrieval­ induced forgetting' phenomenon that they describe. They point out that many demonstrations of behavioural inhibition do not necessarily involve genuine central inhibition, in the sense that the representation of an item is itself inhibited. Many reports of 'inhibitory' mechanisms arise from the relative enhancement of competing items or interference from competing cognitive or motor tasks at the time of output, without evidence of inhibition of the target.

Genuine inhibition of old targets is best demonstrated under conditions where systematic response bias has been eliminated, there is low semantic or lexical confusibility between target items and distractors, and there is little evidence of substantial enhancement of possible competitors. The present studies were not designed as a systematic investigation of inhibitory memory phenomena, and therefore the results cannot be unambiguously determined as inhibitory or noninhibitory. However, the forced choice procedures used in

82 Experiments 1 and 2, combined with the fact that distractor items were

unrelated to the target and that performance in many conditions was at true

chance makes it unlikely that the observed inhibition of familiarity relative to

recognition was due to enhancement of competing responses or to any

obvious confounding of output processes Rather, it suggests that the

inhibitory effects observed are due to inhibition of the target representation

itself.

There are three substantial methodological differences between the

present Experiments 1 and 2, which apparently yielded inhibition of some

familiar items, and those of Bonanno & Stillings (1986), who obtained

facilitation of familiarity responses under similar conditions. Experiments 1

and 2 used lexical stimuli, whereas Bonanno and Stillings used irregular

polygons. The present stimuli were masked, whereas Bonnano and Stillings

presented unmasked stimuli for 1 millisecond. Finally, the instructions were

altered in order to reduce participants' expectations that familiarity responses

could be based upon weaker phenomenal evidence than recognition

decisions. Each of these may contribute to the apparent inhibition of the

familiarity response to items presented once.

Investigating the contribution of familiarity and recognition-based

processes to words rather than polygons was, of course, a primary motivation

of the present study. Unlike new polygons, known words already have a

representation in long term memory, and are in this sense 'familiar'. Hence

"Which did you see ?" is asking whether a pre-experimentally familiar item was encountered in the immediately preceding experimental context, while

83 "Which is more familiar?" does not require participants to attribute their sense of familiarity to a specific experimental event. In the terms of the two-process model adopted by Bonnano and Stillings (1986), familiarity or fluency arises from exposure to the stimulus. Recognition requires that the sense of familiarity is supported by sufficient information about the stimulus at the time of presentation to permit either the automatic or strategic retrieval of semantic or contextual associations. This explains the more typical finding of familiarity in the absence of recognition, but is difficult to reconcile with the present , reversed effect.

However, as already argued, a "familiarity" -based response to known words may be phenomenologically and empirically different from

"familiarity" responses to novel visual stimuli.

Known words are familiar by virtue of being within the vocabulary of the participant. As such, the question Which is more familiar? requires interrogation of the relative status of each of the words offered in the forced­ choice task. One aim of the present experiments was to investigate the extent to which participants are able to reconcile extra-experimental familiarity

(arising from previous experience with the word) with intra-experimental familiarity, arising from the brief masked presentation in this context, and the results suggest that a single presentation of a word in a masking study makes a presented item less, rather than more familiar.

Dagenbach and others (Dagenbach, Carr and Wilhelmsen, 1989,

Dagenbach, Carr and Barnhardt, 1990, Carr and Dagenbach 1990) reported inhibitory semantic priming effects for masked words presented at a masking

84 threshold determined using a semantic judgment task, and for unmasked new vocabulary words following an attempt to retrieve their meaning. Carr and

Dagenbach (1990) attributed these findings to centre-surround inhibition within the semantic network. By analogy with the perceptual system, such an inhibitory mechanism would define the 'edges' of the activated semantic network and prevent uncontrolled activation spreading throughout the network. This inhibition is assumed to be relatively short-lived and to arise in the very specific context of an unsuccessful attempt at word retrieval. More strongly activated associates are inhibited in order to maximise the relative activation of the target item.

The phenomenon described by Dagenbach and colleagues bears an appealing resemblance to that observed in Experiments 1 and 2 on a number of levels. Both use an unusual task to assess the availability of a recently presented stimulus. Both apply under conditions where the original stimulus was only weakly activated- in the present case due to temporal and masking factors, in the earlier research due to these manipulations as well as low frequency and recent acquisition. Both are replicable, but are somewhat fleeting and may be procedure-bound.

However, a fundamental conceptual difference is that the inhibition described by Dagenbach and others appears to arise only in semantic priming tasks, in which participants are searching among competing, semantically related items for the weakly available target. In the present experiments the immediate presentation of the alternative forced choice task following the masked presentation more closely resembles repetition priming

85 for both the recognition and familiarity conditions.

The general centre-surround model proposed by Carr and

Dagenbach (1990) relies, almost by definition, on the failure to obtain these effects in repetition priming. In the case of direct repetition, the logic of a

'centre surround' mechanism becomes confused. As the item is presented as both prime and target, it is both 'centre' and 'surround'. Indeed, Carr and

Dagenbach (1990) provide further support for their centre-surround model by demonstrating that inhibitory priming does not occur in repetition priming.

Nonetheless, Dagenbach and colleagues make clear that inhibitory effects are not produced by the semantic search task itself, but by task-wide priming effects. They argue that task design and instructions constrain the specific response strategies used by participants. The tasks they describe­ such as a threshold-setting task in which participants are required to seek word meaning - results in a global strategy of seeking meaning, which flows through to the subsequent priming tasks. To compensate for the constant re­ addressing of the semantic network surrounding a target, semantic rivals are inhibited, producing inhibitory semantic priming.

As it is the instructions and task requirements, rather than the priming trial itself, which give rise to these experiment-wide strategies, inhibitory semantic priming could, in principle occur in a repetition task, provided participants were attempting to access the meaning, rather than the identity of the prime. Marcel and others (eg Marcel 1983a) suggest that semantic judgements can be made at presentation durations too brief for identity judgements. Under these circumstances, inhibitory semantic priming is, in

86 principle, made possible by the same mechanisms as those more normally yielding facilitatory priming. However, this would only occur if participants did not expect the prime and target to be the same.

In the present Experiments 1 and 2, it is possible that the participants did not consciously identify a sufficient number of items at all during the presentation of the 14 millisecond items in order to form any expectation about the relationship between the study and test items. When asked which was more familiar, they had no reason to assume that either had been presented, and they may well have searched the (inhibited) "surround" of the target item (including the unseen target itself) and the (noninhibited) surround of the foil.

Carr and Dagenbach (1990) suggest that if the trace is strengthened

(in the present case by repetition and longer exposure duration), the inhibitory mechanism disengages itself. This is consistent with the present, admittedly speculative, explanation and would produce the obtained pattern of chance performance on many conditions, inhibition of the familiarity response to a single item, and increasing endorsement on the basis of familiarity with repetition.

The account depends crucially on the 'familiarity' question invoking

(failed) semantic search strategies, while the recognition question relies on

(failed) access to an episodic trace. As explained, the instructions for

Experiments 1 and 2 were modified from those used by Bonanno and

Stillings, because it was felt that Bonnano and Stillings' instructions may lead to an expectation that weakly remembered items should be endorsed as

87 familiar. In the present tasks, participants were encouraged to choose the more familiar item regardless of the source of their sense of familiarity. As they had no reason to expect that either item had been presented in the experiment, they may well have recruited any possible evidence available to them when they were presented with the two alternatives in the test task.

Thus there may have been a search 'around' the semantically activated but unknown target at the time of test, with the centre-surround mechanism inhibiting the item itself. This would produce inhibition of the familiarity but not the recognition judgement for items briefly presented items seen once. It would also account for the general correlation between familiarity and recognition responses in the majority of conditions and for the majority of participants: the two cues are almost always accessing the same construct, but in exceptionally data-deprived conditions, a more complex search process occurs.

Experiments 1 and 2 therefore did yield dissociations between familiarity and recognition of repeated masked words. However, this dissociation was unexpected in the light of previous findings. They provided some evidence that weakly activated items can be inhibited under circumstances where the item was weakly available at the time of initial presentation, and hence have low levels of familiarity within the experiment, despite being moderately familiar due to their being known words.

However, the anomalous relationship between recognition and

'familiarity' in both experiments casts some doubt upon the nature of the trace being accessed by the direct familiarity cue, and the locus of inhibition of that

88 trace. As long as familiarity and recognition are assessed using different tasks, it is not possible to precisely describe the nature of the relationship between these two bases of responding, especially given the obtained correlations between the two tasks

An alternative approach is to investigate the effects of familiarity indirectly, by manipulating conditions known to influence the familiarity of a stimulus, and then to use a single dependent measure to assess the impact of these manipulations. This procedure is adopted in Experiments 3 to 6.

Experiments 3 and 4 develop a novel repetition priming paradigm in which number of presentations and number of responses, word frequency, and lexical status are manipulated with partial independence within a standard repetition priming task. This will permit more sophisticated diagnosis of the effects of pre-experimental familiarity, novelty, reprocessing and response practice upon familiarity- and recognition- based responding. In Experiment 3, the priming trial is masked. In Experiment 4, no masking is used.

89 Chapter 3. Experiments 3 and 4

3. 1 Rationale and Overview: Experiments 3 to 6

Experiments 1 and 2 suggested that the likelihood of weakly activated words being selected increases with number of repetitions in response to the question Which is more familiar? but not in response to Which did you see?

Furthermore, correct selections were initially lower for the familiarity than for the recognition task. It was suggested that there may be some temporary inhibition of retrieval of very weak (singly presented) items on the basis of judged familiarity.

As suggested at the conclusion of Chapter 2, the use of the direct familiarity cue Which is more familiar ? may result in conflict between familiarity within the experiment - arising from prior processing and repetition, and familiarity associated with pre-experimental factors, such as the baseline frequency of the target word. The overall eventual selection of an item as familiar does not allow investigation of the contribution of each of these aspects of familiarity. An alternative approach to disentangling these competing aspects of familiarity is to manipulate the possible variables contributing to the sense of familiarity, and to assess the impact of these manipulations upon retrieval measures. Experiments 3 to 6 adopt this approach. They are based upon standard lexical decision (Experiments 3, 4,

5) and naming (Experiment 6) paradigms. Pre- and intra-experimental familiarity are systematically manipulated within the study task. The effects of these manipulations on lexical decision RT (Experiments 3,4,5), naming

90 latency (Experiment 6), recognition memory (Experiments 5 and 6), perceptual identification (Experiment 5) and recognition exclusion

(Experiments 5, 6) are then investigated.

As outlined in Chapter 1, there is evidence for phenomenal episodic, instance-specific, and lexical contributions to repetition priming. The three accounts differ on a number of dimensions, and result in different predictions as to the acquisition, locus and robustness of priming effects. As outlined in that Chapter, it is expected that none of these explanations will be sufficient in accounting for repetition effects These experiments are designed to determine the relative contribution of each mechanism. The extent to which repetition priming relies upon conscious access to a representation of the encoding experience provides the critical test between the phenomenal episodic account and the other two explanations. Distinguishing the two acquisition-based views from the third, modification account depends on determining whether the repetition effect depends upon the participant's pre­ experimental experience with the item. The role of pre-experimental experience is investigated by comparing performance for words and nonwords, and for high and low frequency words. Participants have obviously had more experience with words than nonwords, and with high than low frequency words.

Experiments 3 and 4 develop a study paradigm in which high frequency and low frequency words and nonwords are presented once or twice. Concurrently with each presentation, participants are provided with a cue indicating whether or not to respond. Hence word frequency, lexical

91 status, number of intra-experimental presentations and number of intra­ experimental responses can be manipulated with partial independence. If repetition effects in all tasks are determined by total prior exposure to a word, regardless of the nature or context of that exposure, then it is more parsimonious to suggest that a single, modification-based mechanism is responsible for retrieval of repeated items. However, if the influences of pre­ and intra-experimental exposure are dissimilar within tasks or inconsistent between tasks, it is unlikely that a unitary account will be sufficient. As the relationship between the nature of the study task and retrieval performance becomes more specific, the case for an instance-based episodic mechanism becomes stronger.

In Experiment 3, nonresponse presentations are masked, consistent with Experiments 1 and 2. Experiment 4 is identical with Experiment 3 except no masking is used. In Experiments 5 and 6, longer term direct and indirect retention for items accessed during this task is also assessed using Process

Dissociation (PD) procedures.

3. 2 Experiment 3

In a series of experiments exploring masked repetition effects, Forster and Davis (1984, See Chapter 1) established that repetition effects for words can be obtained when the participants have no awareness of the prime due to brief presentation and forward and backward masking. Although frequency effects were still evident in reaction time to targets with masked primes, the frequency attenuation effect was eliminated, and no priming was obtained for nonwords, leading to the conclusion that the frequency attenuation effect

92 depends upon the participant having some subjective awareness of the priming item. Furthermore, the magnitude of priming appeared to depend upon the task-relevant processing of the prime, as items presented as context

(filler) items in a lexical decision task did not show priming when compared with those that had been the subject of a prior lexical decision judgement

(Experiment 4). Experiment 3 adapts the Forster and Davis (1984) paradigm to permit more direct comparison between the effects of multiple presentations and multiple responses.

Method.

Participants. Participants for Experiment 3 were 20 university students and graduates who participated in the studies for course credit or as volunteers. All were competent English speakers who had spoken English predominantly for at least ten years.

Stimuli. The critical experimental items consisted of 80 low frequency

(1-2 per million ) and 80 high frequency (40-60 per million) words of between six and eight letters in length. Words were selected from the MRC

Psycholinguistic Database (Coltheart, 1981) using frequency estimates from the Kucera & Francis (1967) norms. The nonwords consisted of 160 pronounceable, nonpseudohomophonic nonwords created by replacing 1 to 3 letters of other words the same length as the target words. These 320 items comprised the critical target list. The target list was randomly divided into two sub-lists each comprising 40 high and 40 low frequency words and 80 nonwords. Participants thus made lexical decision responses to 160 items.

Each of the two lists of target stimuli was randomly assigned to half of the

93 participants to evaluate the generality of repetition effects across different item lists.

A further 240 mid frequency words (5-20/ million) and 240 nonwords were randomly selected for use as fillers. Fillers were interleaved between the critical items with the constraints that at least two intervening items should separate any two responses and that it should not be possible to predict the lexical status of the target item from the fillers preceding it. Where an item was presented twice and the response cue provided on only the second presentation, the repetition always immediately followed the first presentation of the item (i.e lag = 0). Where a response was required to both the first and second presentation, a uniform lag of two items separated the two presentations to overcome possible refractory effects. 1

Although fillers were initially allocated randomly, it was not procedurally practical to randomise the fillers surrounding a given critical item.

Therefore, although the order of the short sequences of fillers and targets was randomised, the particular filler items surrounding a given target remained constant.

A backward pattern mask was created from nonletter characters.

A typical trial would proceed as follows. Participants are pre-cued to make lexical decision responses only to items in capital letters and to make no respnse to any lowercase item. Hence in this trial they would only respond

1The implications of this confounding of repetition type with massed versus spaced repetition will be reviewed in the Discussion.

94 to the second presentation of the word MACHINE. They would not respond to any lowercase word or nonword regardless of the number of times it was presented.

Forward Mask-filler sequence varies between 0 and 3 No response response cue mask fillers. cue Stimulus Mask Filler Mask Filler Mask Prime Mask Target

Duration 500msec 14msec 500msec 14msec 500msec 14msec 500msec Until response Display @#$&#@ Process @#$&#@ Language @#$&#@ machine @#$&#@ MACHINE

Procedure: The experiment was run using the DMASTR package on an industry standard 386 PC in a quiet room. Participants were seated approximately 1 metre from the screen. Responses were registered via a pair of response keys, such that the 'yes' response was always registered with the dominant hand. A foot switch was used to initiate the practice trials and the experimental set. Participants were informed that they were participating in a word detection recognition experiment. They would see strings of letters and

'squiggles' in centre of the screen. They were instructed to attend to each string of letters as it appeared on the screen, but only to respond to strings of letters presented in capital letters. If a string in capital letters formed a word, they were to press the 'yes' key as quickly as possible; if it did not form a word, they were to press the 'no' key. Twenty practice items were presented, after which participants initiated the main set when they were ready to continue.

Stimuli were presented in a continuous sequence, each for 14 milliseconds followed by a backward mask for 500 milliseconds, then a 520 95 millisecond lSI. If a response was required, the item remained on the screen until the response was registered, followed by a 520 milliseconds lSI. Thus although the stimulus duration of the final target varied with response time, the manipulation of number of responses did not systematically increase total exposure duration beyond that in those conditions where multiple responses were not required . Overall, 640 stimuli were presented to each subject, with responses required to 160. The experiment was run in a single 30-minute session, including instructions, practice and debriefing.

Results.

Lexical decision times and error rates for each condition of

Experiment 3 are presented in Figure 2 and Table 6. Mean correct reaction times and error rates were calculated separately for each condition, and separate ANOVAS conducted on each dependent variable. Factors included in the analysis were list, lexical status (word vs nonword), frequency (high vs low), number of presentations (1 vs 2), and number of responses (1 vs 2).

Unless otherwise stated, all significance levels are set at 0.05.

96 950 A··············· ...... 900 ·········· ... 850 ------'"" '... ·,, ...., ·· ...... ------', •, 1/) 800 .§. ' '•, e I= 750 ',,, ······ ... c -High Frequency 0 ' u; ', ·· .... - .. - Low Frequency u ', ':t. ~ 700 ··•··Nonwords 'B ' ' x ' ' j 650 ' ' ' ' ' 600

550

500~------~------~------~ New Simple Repetition Response Repetition Repetition condiUon

Figure 2. ,Experiment 3. Mean reaction times (milliseconds) for high frequency words, low frequency words and nonwords. New = nonrepeated item, Simple repetition = item repeated with response to second presentation only. Response repetition= Presentation and response repeated.

Latency: Significant main effects were obtained for frequency [F(1, 18)

= 27.13] and lexical status [F(1,18) = 27.90]. Overall, items presented twice were classified more quickly than those presented once [New versus the average of simple repetition and response repetition, F(1, 18) =31.73], and those requiring two classification more quickly than those requiring only one

[simple repetition versus response repetition, F(1, 18) = 51.80].

Overall, the comparison of those conditions where items were presented twice (Simple repetition and response repetition) with new items suggested that reaction time to words was facilitated by multiple presentations, while nonwords did not show any priming as a result of repeated presentations, yielding a significant interaction between lexicality and number of presentations [F(1, 18)= 5.87].

97 Table 6: Experiment 3. Mean Percentage errors for high frequency words. Low frequency words and nonwords, New= nonrepeated item, Simple repetition= item repeated with response to second presentation only. Response repetition = Presentation and response repeated. Standard deviations in parentheses.

Repetition Condition New Simple Response Repetition Repetition. High 2.0 5.5 1.0 Frequency (5.2) (1 0.5) (3.07) Low 7.5 7.5 7.5 Frequency (7.9) (8.5) (9.1 0) Nonwords 9.25 6.0 6.0 (11.9) (7.9) (13.7)

Frequency and response repetition interacted significantly [F(1, 18)=

17.2], with low frequency words benefiting from a second response to a

greater degree than high frequency words.

However, the above effects are entirely attributable to the very fast

responses to the repeated response conditions, in which the first presentation

was unmasked and required a response. The results are only significant

when the response repetition condition is also included as a multiple

presentation condition, reflecting the comparison of all conditions in which the

stimulus was repeated with those in which it was not. No significant priming was found for any class of items in the simple repetition condition. [New

items versus repetition alone, F<1 for high frequency words and nonwords].

98 The 38 millisecond inhibition of reaction time for low frequency words in the repeated presentation conditions was not significant, [F(1,18) =3.13, ns]. In contrast, all 3 classes showed significant facilitation when both presentations required a response compared with repeated presentation only [High frequency words F(1,18) = 23.65, low frequency words F(1,18) = 44.27, nonwords F(1, 18)= 30.89].

Errors: Lexical decision performance was more accurate for high than for low frequency words [F{1,18) =11.57]. There was no significant difference between words and nonwords [F(1,18) = 1.04], and no effect of number of presentations or number of responses (both Fs < 1). No interactions between these variables were significant

Discussion.

Simple repetition: There was no significant evidence of any processing of masked stimuli in Experiment 3. All significant priming effects were attributable to differences between the simple repetition and the response repetition conditions. The fact that frequency and lexicality effects were not obtained under the present masking conditions is clearly inconsistent with findings such as those of Evatt and Humphreys (1981) and

Forster and Davis (1984), and suggests some crucial differences between the present study and those earlier ones.

The present study has similarities to Forster and Davis' (1984)

Experiments 1 and 5, but differs from those experiments in terms of the organisation of masking trials and the exposure duration of the primes.

In Experiment 1 of Forster and Davis, the target followed immediately

99 after the priming word, and indeed the target word comprised the backward mask of the prime. In the present experiment, if a response was required to only the second presentation, the target was the next lexical item to follow the prime. However, in the present study, an additional item- the nonlexical backward mask- intervened, effectively introducing a 500 millisecond or 1 item lag between target and mask. In Forster and Davis' Experiment 5, the items and fillers were presented in continuous masked stream, with only the targets visible- again procedurally similar to the present study. A lag of at least one item intervened between nonresponded masked prime and the unmasked target. Although the priming effect was reduced by the introduction of the lag, Forster and Davis still obtained significant masked repetition effects in Experiment 5. It is therefore unlikely that the failure of the present data to replicate those effects is attributable to the lag imposed by the mask intervening between prime and target.

The presentation duration of the prime was also far shorter in the present study than in previous masked priming studies. Fourteen milliseconds is less than a quarter of the 60 millisecond exposures used by

Forster and Davis (1984) and well below the range of 24 to 60 milliseconds reported by Humphreys and co-workers (Evatt & Humphreys, 1981;

Humphreys, Evatt, Quinlan & Besner, 1987). The most plausible explanation of the present null finding is that the stimulus exposure was so brief that it became perceptually fused with mask, preventing any measurable processing of the prime, and hence eliminated any priming.

The duration of the priming stimulus, and indeed all stimuli in the filler

100 sequence, was determined in part by the results of Experiments 1 and 2, which suggested that the very weak activation arising from masked 14 millisecond presentations may give rise to an inhibition of the sense of familiarity, despite repetition of the stimulus. Thus although there was no experimental precedent for such short exposure durations, the perplexing interaction between such brief exposures and repetition determined this aspect of the present procedure. The present results suggest that the evidence of inhibition of familiarity judgements of words presented for 14 milliseconds obtained in Experiments 1 and 2 was task-specific, and most appropriately accounted for in terms of task-wide participant strategies or decision rules, as outlined in the discussion of those two Experiments.

Response repetition: Notwithstanding the failure of the present experiment to yield masked repetition priming, the effects of (unmasked) response repetition can still be considered. Although high frequency words were responded to more quickly throughout the experiment than other item types, they gained less benefit from multiple responding than either low frequency words or nonwords. The reduction of the magnitude of the frequency effect as a result of repetition is, of course, the typical frequency attenuation effect found with unmasked repetition priming. However, the results also suggest a lexicality attenuation effect, with word and nonword reaction times converging as a consequence of response repetition.

Experiment 3 did not satisfactorily distinguish between the effects of stimulus repetition alone and those of stimulus and response repetition, arguably because of the overly rigorous masking procedure employed.

101 However, the results did suggest that low frequency words and nonwords gain greater benefit from multiple responding than high frequency words if the prime and target are not masked. Experiment 4 is a replication of Experiment

3 without the masking procedure. It will permit greater clarification of the interactions between simple and response repetition, lexicality and frequency than was possible with Experiment 3.

3. 3 Experiment 4.

Experiment 4 used a lexical decision task to compare the effects of simple repetition of a stimulus with repetition of both the stimulus and a lexical classification response. High and low frequency words and pronounceable nonwords were presented once or twice, in lower case or upper case.

Participants were instructed to make a lexical classification response only to upper case stimuli.

Method

Participants: 32 undergraduate students participated in Experiment 4 for optional course credit. Other participant requirements were as stated for

Experiment 3.

Materials and procedure. Experiment 4 used the same items and distractors and the same trial organisation as Experiment 3. in Experiment 4 no items were masked. In each trial, the final target item (the item from which response latency was measured) remained on the screen until a response was registered, while any previous presentation of the target and all nontargets remained on the screen for 520 milliseconds.

102 Results

Neither lexical decision times nor error rates differed significantly

between the two item lists (both Fs<1), nor did list enter into any significant

interaction in lexical decision time or error rates. This factor is therefore

ignored in reporting the results. Figure 3 gives the lexical decision times for all

conditions.

900 ...... 850 •, •, '•, '• ··. 800 '• •, (/) '• '•. .§. '• ·· Q) 750 ...... E ...... i= ...... c ...... -High Frequency 0 ...... ·u; 700- ...... --+-Low Frequency ·c:; ...... _ Q) ·· * · ·Nonwords c ---- (ij --- u 650 --- ";( -----... Q) ...1 600

550

500 New Simple Repetition Response Repetition Repetition condition

Figure 3: Experiment 4: Mean reaction times (milliseconds) for high frequency words, low frequency words and nonwords. New = nonrepeated item, Simple repetition = item repeated with response to second presentation only. Response repetition= Presentation and response repeated

Overall, large and significant Reaction Time effects were found for

lexical status [F(1 ,30) = 118.40] and frequency [F (1,30) =52.36]. Average

response time was 175 milliseconds faster for words than nonwords, and high

103 frequency words were classified 81 milliseconds faster than low frequency words

Marked overall repetition priming was evident with an average of 32 milliseconds facilitation when the item was presented twice but only required a response to the second presentation [New vs Simple repetition, F(1 ,30)

=34.56], and an additional 48 milliseconds when the both presentations had required a classification response [Simple vs Response repetition , F(1 ,30) =

27.75].

Both facilitation effects were of significantly greater magnitude for low frequency than high frequency words [New vs Simple repetition, F(1 ,30) =

27.13 , Simple vs Response repetition, F(1,30) = 14.33]. Repetition of a previously unclassified item yielded significant priming for high frequency

[New vs Simple repetition, F(1 ,30) = 5.74] and for low frequency words [New vs Simple repetition F(1 ,30) = 28.99]. Repetition of a previously classified item yielded no significant additional priming for high frequency words [Simple repetition vs Response repetition, F(1 ,30) = 1.23, ns] but significant priming

(25 milliseconds) for low frequency words [Simple repetition vs Response repetition, F(1 ,30) = 7.38]. Thus, both high and low frequency words benefit from prior presentation of the target alone, but low frequency words show significantly greater priming than high frequency words from both repeated presentation and repeated responding.

The effects of repetition interacted with lexical status [F(1 ,30) = 12.20] because, although words benefited from previous presentation of the target alone (New vs Simple repetition), no such facilitation occurred for nonwords.

104 Indeed, a small (7 milliseconds) delaying of nonword classification latency was observed when the nonword had been presented on the preceding trial without a response requirement. A large (114 milliseconds) and significant

[F(1 ,30)= 49.53, p < 0.01] facilitatory effect of repetition was obtained for nonwords, however, when the previous presentation had required a response. Thus while words showed repetition priming both when the item alone was repeated and also when a repetition of the classification decision was required, nonwords showed repetition priming only with repeated classification. Table 8 provides the error data for all conditions

Table 8. Experiment 4. Mean Percentage errors for high frequency words. Low frequency words and nonwords, New = nonrepeated item, Simple repetition= item repeated with response to second presentation only. Response repetition= Presentation and response repeated. Standard deviations in parentheses.

Repetition Condition New Simple Response repetition repetition High 2.5 1.6 0.6 Frequency (5.6) (4.5) (2.5) Low 9.7 4.7 11.6 Frequency (12.0) (7.6) (12.2) Nonwords 7.0 16.6 8.4 (9.1) (10.4) (8.7)

Analysis of the error data showed that participants were significantly more accurate in classifying words than nonwords [F(1 ,30) = 23.43], and high

105 than low frequency words [F(1 ,30) = 15.57]. There were significant

interactions between lexical status and repetition condition [F(1 ,30) = 12.95

for simple repetition, F(1 ,30) = 8.68 for response repetition] and between

frequency and response repetition [F(1 ,30) = 6.35], with low frequency words

producing significantly more errors than high frequency words following two

responses.

As the pattern of errors for low frequency words and nonwords

appeared complementary, further analysis was conducted including only

these two classes of item. Compared with simple repetition, repetition of a

previously classified stimulus was associated with an increase in error rate to

nonwords but a decrease in errors to low frequency words [F(1 ,30) = 28.87].

Conversely, the comparison of errors to stimuli classified only on their second

presentation with those responded to on both presentations revealed a

decrease in errors to nonwords but an increase in errors to low frequency

words [Low frequency words vs. nonwords X simple repetition, F(1 ,30) =

28.52]. Thus repetition of a previously unclassified stimulus was associated

with the highest error rate to nonwords but the lowest error rate to low frequency words.

3.4 Discussion: Experiments 3 and 4.

The results from Experiments 3 and 4 suggest that more than one mechanism contributes to the interactions between repetition and lexicality and frequency. Nonwords did not show priming in reaction time unless a response had been made to the previous presentation, although there was evidence in Experiment 4 that errors increased as a result of unclassified

106 repetition. In contrast, high frequency words benefited only from repetition of the word but gained nothing extra from repeated classification. Low frequency words benefited from both repeated presentation and repeated responding.

The contrast between the masked and visible presentations of

Experiments 3 and 4 suggests an interesting combination of relationships between low frequency words and both nonwords and high frequency words.

Reaction times overall were approximately 100 milliseconds slower in the masked experiment, suggesting that the sudden appearance of the target item against the flickering masks is more disruptive to lexical decision performance than the visible filler items in Experiment 3. The application of masking particularly disrupted lexical decision for low frequency words, which showed nonsignificant slowing with simple repetition in Experiment 3 and significant facilitation in the same condition in Experiment 4.

Lexical status

Nonword reaction times showed no priming from previous exposure to a stimulus that required no response. Moreover, error rates were higher for immediately repeated nonwords than for nonwords presented for the first time. The opposite effect was evident in the error data for low frequency words that were classified most accurately following previous exposure with no response requirement.

The most likely explanation of the differential effect of exposure alone on nonwords and low frequency words is that an immediate repetition of a stimulus, whatever its lexical status, induces a tendency to classify it as a

107 word. Feustel et al (1983) suggest that the lexical decision task is

inappropriate for assessing repetition effects for nonwords, because repetition

of a nonword can have two opposing effects. The item is more familiar, and

may therefore be harder to reject than a nonword presented for the first time.

Conversely, having already conducted the perceptual processing required to

identify the stimulus might be expected to yield facilitation due to practice

effects or procedural priming.

The effects of simple repetition of a nonword seem to conform to

Feustel et al. 's prediction about the impact of nonword familiarity on lexical

classification. Repeated nonwords become familiar, and participants are

biased to respond "word" to familiar items. This bias is reflected in reduced

classification accuracy for immediately repeated nonwords, but increased

accuracy for immediate repetitions of low frequency words, since rare words

which might otherwise have been wrongly classified as nonwords benefit from

the shift in criterion towards "word" responses. By this interpretation, the

effects of immediate repetition are irrelevant to the distinction between

acquisition and modification based theories because they arise from a direct

effect of repetition on response selection.

But questions remain as to the exact basis of the familiarity presumed to yield a bias toward word responses in the present experiments. It cannot

be attributed to straightforward repetition of perceptual features because the first and second stimulus presentation were in different formats: the first,

unclassified presentation was in lower case while the second word was in

upper case signalling that a response was required. Therefore the familiarity

108 mechanism must be relatively impervious to changes in the surface structure of the stimulus. Instance-specific, episodic mechanisms such as relative perceptual fluency (Jacoby & Dallas, 1981), are usually regarded as specific to the particular surface format of the original encoding episode. Conversely, resistance to changes in surface structure is usually claimed to reflect an abstract representation of the stimulus that is modified rather than newly acquired with each encounter. That is, an effect of repetition on nonword performance that survives surface change implies that a single presentation of a nonword that requires no explicit attention or classification yields an abstract representation that can be re-activated on subsequent re­ presentation of the nonword. By this argument, the data provide evidence of a contribution of modification-based mechanisms to nonword repetition priming.

As the nonwords used in the present study are all pronounceable and orthographically legal, the target of the modification may be a rapidly acquired lexical component (developed over a single classification trial), or a range of sublexical components shared by the selected nonwords and real words.

Rugg and Nagy (1987) obtained evidence separating legal and illegal nonwords on the basis of ERP activation, supporting the suggestion that effects of nonword repetition are dependent upon the sublexical attributes of legal nonwords. The implications of these findings for the present studies are reviewed in Chapter 6. For present purposes it is merely noted that, insofar as repetition effects for nonwords may rely upon sublexical components, they nonetheless differ from word priming effects in that these components do not

109 appear to confer any pre-exposure familiarity upon the whole item. Since at least one presentation is required before sublexical components yield confusion of nonwords with words, a 'pure' (in Tenpenny's, 1990 terms) sublexical explanation is implausible.

In contrast to the inhibitory effect of simple exposure to a nonword, repetition of a nonword that was classified on its first presentation yielded marked facilitatory priming on subsequent lexical classification of the same stimulus. This effect is consistent with the involvement of conscious episodic traces established through prior classification of a nonword stimulus. The contrast between the inhibitory effects of simple repetition of a nonword and the facilitatory effects of a previously classified nonword implies that nonword priming can arise from either quickly developed abstract representations or conscious episodic traces.

Before accepting this conclusion it is important to eliminate two confounding features of the design of the lexical decision task of Experiment

4. In addition to the difference in prior response history between the Simple

Repetition and Response Repetition conditions, there was a difference in repetition lag. Repetitions of an unclassified item occurred immediately, while repetitions of classified stimuli followed two intervening items. Although, in principle, the case change between immediate repetitions rules out an explanation based solely on perceptual features, the overlap between the lower and upper case versions of many letters weakens this argument.

Repetition effects that survived the perceptual masking produced by intervening items would provide stronger evidence for the establishment of an

110 abstract representation from a single passive exposure to a nonword. This is the procedure adopted in the study tasks of Experiments 5 and 6.

The basis of the facilitatory nonword repetition effect due to a previously classified stimulus also requires further specification. This effect might arise because the processes involved in classifying a nonword establish an episodic representation of the stimulus that is available to be accessed when it is presented again. Alternatively, the classification response itself may be learned, such that it is easier to make the same response when the same stimulus is presented again. By the first account, the representation is independent of the response that was made, and should be available in a subsequent task requiring a different response. If, however, nonword priming is the result of specific stimulus-response pairing, there is no expectation that priming will occur when the same item is presented in a task requiring a different response. These issues are investigated by including tests of recognition memory in the subsequent experiments.

Word frequency

High frequency words were classified more quickly than low frequency words overall, but repetition effects were greater for low than for high frequency words. Many previous studies have obtained interactions between frequency and repetition (eg Scarborough, Cortese & Scarborough,

1977 Jacoby & Dallas, 1981 Forster & Davis, 1984, Rugg, 1990). The novel contribution of the present experiments is that they clearly demonstrated that the enhanced priming observed for low frequency words holds both for items that were initially presented with no response requirement (Experiment 4),

111 and for items classified on both their first and second presentation

(Experiments 3,4). These two interactions might reflect different mechanisms contributing to repetition effects.

Theoretical accounts of the differential repetition effects for high and low frequency words suggest that the interaction reflects the involvement of a common mechanism contributing to effects of both frequency and repetition.

Those who argue for a 'lexical' account of the interaction (eg Mansell, 1985) describe the common mechanism as the relative activation of high and low frequency words in a frequency-ordered lexicon. Decay parameters in this system are such that less common words require more activation to achieve threshold, but remain disproportionately active following a single presentation.

Thus low frequency words yield longer average identification times, but larger repetition effects than high frequency words.

An alternative 'episodic' explanation of this interaction asserts that the interaction between frequency and repetition is produced by the acquisition of episode-specific representations of words. As high frequency words have been encountered more often and more recently than low frequency words, they are recognised more readily, but are less likely to result in the establishment of a representation specific to any particular episode (eg

Feustel, et al., 1983, Jacoby & Dallas, 1981).

Rather than reflecting a single mechanism, the interaction between effects of word frequency and repetition in behavioural performance may arise from the combined influence of different underlying mechanisms. For example, Forster and Davis (1984) used the evidence that backward masking

112 preserves word frequency effects but eliminates frequency attenuation to suggest that, while the word frequency effect per se reflects differential access times for high and low frequency words, the frequency attenuation effect has its locus in retrieved episodic information.

Rugg (1990) reported electrophysiological evidence suggesting that event-related potentials (ERPs) elicited by repeated stimuli are modulated by both baseline frequency (word frequency) and intra-experimental frequency

(repetition), but that the two effects were reflected in different ERP components and may therefore arise from different underlying processes. The results of Experiment 4 are amenable to similar argument. Word frequency

(baseline familiarity) and intra-experimental experience exert differential influence upon the existence and extent of repetition effects, and may therefore represent different aspects of the memory basis of priming.

Experiments 5 and 6 adapt the present paradigm to provide more direct evidence about the processes contributing to differential repetition effects for high and low frequency words and nonwords. By using lexical decision and naming tasks as study conditions and investigating the effects of the simple and response repetition on subsequent retrieval tasks, they serve to disentangle the task-dependent and task-independent effects of repetition.

By using process dissociation methods in the test tasks, they permit another operationalisation of familiarity to be used as a dependent measure.

113 Chapter 4: Dissociating familiarity ancll recollection

The results from Experiment 4 suggested that lexical classification of low frequency words are facilitated by repeated presentation whether or not the item was responded to on its initial presentation. As discussed in Chapter

3, it is possible that baseline and intra-experimental familiarity reflect different mechanisms in priming, and that these aspects of familiarity are themselves differentially influenced by the manipulation of repetition and response variables.

A second key finding was that nonwords, while not showing any priming in lexical decision time, yielded a pattern of errors consistent with the view that repeated letter strings are more likely to be endorsed as words (e.g.

Feustal, et al.,1983).

Each of these results can be described as demonstrating a relationship between repetition and familiarity, however familiarity appears to be a nonunitary construct, reflecting a combination of lexical, sublexical, intra- experimental and pre-experimental factors. As Experiments 3 and 4 were not based upon any single theoretical or operational definition of 'familiarity', any discussion of the nature of the mechanism itself remains speculative.

In order to clarify the mechanisms producing each of these findings,

Experiments 5 and 6 combine within- task priming with between-task measures of the familiarity and retrievability of items. Experiment 5 continues to use lexical decision, while Experiment 6 adopts a word naming task. Each

114 priming task is followed by yes-no recognition or recognition exclusion tasks

(see below). The recognition and exclusion tasks are of a form appropriate to the application of process dissociation techniques (Jacoby 1991 ), which permit the division of sources of retrieval into 'conscious' and 'unconscious' origins. In Experiment 5, perceptual identification task is also included as an indirect memory measure.

4. 1 Process Dissociation (Opposition ) procedures.

Task and process dissociations.

The distinction between direct and indirect memory measures has been reviewed above (Chapter 1). However, Jacoby (1991) emphasises that although dissociations between memory tests have contributed to important theoretical developments in our understanding of both normal and abnormal memory processes, the dissociations observed do not, of themselves, provide conclusive evidence for the separation of fundamental cognitive processes or mechanisms. Dissociations between, for example, recognition (direct) and fragment completion (indirect) do not commit us to any strong conclusion about the mechanisms or systems serving those tasks. They demonstrate only that people typically behave differently in two very different retrieval tasks. Similarly, the terminology 'implicit/explicit' presumes a construct purity of tasks which has not been empirically justified. Not informing participants that fragment completion is a test of retrieval does not guarantee that their performance upon that task is a pure measure of •implicit• memory. It is likely that at least some participants will use their conscious recollection of the

115 previous list as a guide to the completion tasks.

Several authors (eg Challis and Brodbeck, 1992, Bassilli, Smith and

Macleod, 1989, Hirshman, Snodgrass, Mindes, & Feenan, 1990) have

obtained evidence that at least one common 'indirect' task, word stem

completion, is influenced by the degree of elaboration at encoding- a finding

more typical of direct tasks. One implication taken from this is that the task

may be 'contaminated' by direct memory processes. Process-Dissociation

procedures have been used to demonstrate and estimate the extent of this

contamination (Toth, Reingold and Jacoby, 1994).

Process Dissociation.

Jacoby (1991) argues that the contribution of conscious recollection

and unconscious retrieval processes can only be properly investigated under

conditions where items studied under common conditions are tested using

common retrieval tasks. Any differences obtained between them can

therefore be unambiguously attributed to cognitive processes rather than to

task differences. While the logic of this argument is compelling, it is difficult to

establish a single task which can be identified as 'direct' in some

circumstances and 'indirect' in others.

Jacoby's solution (Jacoby Kelley, 1987; Jacoby, Woloshyn & Kelley,

1989; Jacoby, 1991) is to use a single test task, but to alter the instructions in

such a way as to contrast between conditions in which participants are

encouraged to endorse old items with conditions where they are to exclude them from retrieval. In the former inclusion condition, retrieval involves endorsing all items from the critical list of previously studied items and

116 rejecting all others. In the exclusion task, participants are to reject items from the critical list. Thus identical study and test lists can be used, and the conceptually crucial contrast is between the effects of the instruction to endorse or reject old items.

In the exclusion task it is presumed that if participants are able to consciously recall their previous encounter with the item, then they will comply with the instruction to reject it. Hence the endorsement of an old item under exclusion instructions reflects both the fact that the item is retrieved from the previous encounter, but also that the participant cannot consciously recall the encoding context. For this reason, the exclusion task provides a powerful methodology for clarifying the extent to which retrieval is based upon conscious recollection of the encoding episode, and may serve to specify the mechanisms contributing to the repetition priming effect obtained in the present Experiments 3 and 4. In Experiments 5 and 6, false alarms arising from the attempt to exclude critical items from a recognition task are taken as an estimate of the impact of influences beyond the strategic control of the participant.

Process dissociation procedures do not map conveniently to either the direct/indirect or the explicit/implicit distinction, but they provide evidence of the extent to which a specific previous occurrence of the item can be identified with a consciously retrieved encoding episode. Hence, in the context of the present project, process dissociation procedures may illuminate the role of phenomenal episodic mechanisms to repetition priming of words and nonwords.

117 Jacoby and others ( Jacoby, 1991, Jacoby, Toth and Yonelinas,

1993) provide a series of algorithms by which the contribution of recol/ective

(or conscious or intentional) and automatic (or unconscious or familiarity) to a single task can be estimated. These 'process' estimates are based upon the presumption that in an inclusion task (eg standard recognition), participants will endorse familiar items regardless of their awareness of the source of their sense of familiarity. In contrast, in exclusion tasks, retrieval will be based wholly on non-conscious familiarity. Subtraction of the probability of retrieval of an item under exclusion instructions from the probability of the same items being recalled under inclusion conditions provides an estimate of the independent contribution of recollective processes alone.

The formal statement of the original process estimates is as stated below. In all equations R refers to the recollective component and A to the automatic component of retrieval (Jacoby 1991, Jacoby et al., 1993, Curran &

Hintzman, 1995).

In inclusion tasks, the probability of retrieving an item is equal to the probability of it being recollected (R), plus the conditional probability of it not being recollected, but being retrieved automatically; (1-R)A.

Hence:

Inclusion = R + (1 - R) A. (1)

In the exclusion task, recollected items are not to be retrieved, hence the R term is deleted

Exclusion= (1 - R) A (2)

118 The process estimates outlined above thus become:

R = inclusion - exclusion (3)

and

A= exclusion I (1-R) (4)

Hence the independent contribution of both automatic (familiarity) and recollection-based processes is argued to be estimable from the inclusion and exclusion tasks.

4. 2 Applications of Process Dissociation Procedures

Utilisation of process dissociation procedures has extended our understanding of the nature and value of indirect memory tasks, allowing exploration of some of the empirical contradictions which have been obtained with more conventional memory tests.

Considerable attention has been paid to the stem completion task and the extent it relies upon recollective and automatic processing components. A series of studies have demonstrated that this task is susceptible to levels of processing (or elaboration) effects. Challis and

Brodbeck (1992), for example reliable obtained superior stem completion task performance under 'deep' rather than 'shallow' encoding conditions, while others have found that both picture and stem completion tasks are improved by self-generation of the stimuli. (Bassilli, Smith and Macleod, 1989,

Hirshman et al., 1989).

Toth, Reingold and Jacoby.(1994) successfully used the process dissociation methodology to support the claim that these apparent levels of

119 processing effects in completion tasks arise because the task is

'contaminated' by conscious recollective processes. They found that although overall stem completion performance was enhanced by semantic encoding tasks, the comparison of inclusion with exclusion stem completion tasks yielded an A term which remained constant for semantic and nonsemantic study conditions. This suggests that the additional benefit stem completion gains from elaboration is due entirely to recollective processes.

The finding of normal indirect and impaired direct memory among amnesics has also been replicated using process dissociation procedures by

Cermak, Verfailaellie, Sweeney & Jacoby (1992). They found that, unlike nonamnesic alcoholic controls, participants with alcoholic Korsakoff's disease were as likely to endorse old words in the inclusion as the exclusion condition.

This confirms that their selection of old items in both tasks was attributable to unconscious, fluency-based mechanisms, as may have been assumed on the basis of studies using direct and indirect memory tests.

However, the amnesic group also completed more stems with targets overall (ie. in both the inclusion and exclusion conditions), while performing more poorly than controls on a standard recognition test for words from the inclusion and exclusion conditions. Cermak et al. (1992) explain these apparently anomalous results as follows:

Amnesics may be more responsive than controls to the fluency generated by prior presentations, because they are less capable of determining its source. That is, while controls can consciously choose to use a stem completion other than the one that is familiar, amnesics are unable to do so. (1992, p372)

120 Implicit in the first sentence of above statement is the suggestion that amnesics are not only more reliant upon fluency-based processes, as might be expected, but that they are more sensitive to them than nonamnesic controls, reflected in their better than normal retrieval in both inclusion and exclusion tasks. This in turn requires explanation. Either the amnesics have developed some form of remedial hypersensitivity to familiarity-based information, or among normals, the presence of conscious processes inhibits the degree to which responses are influenced by familiarity. The tenor of the above statement is more strongly suggestive of the second rather than the first of these accounts, raising the intriguing suggestion that conscious retrieval may reduce the likelihood of selecting a familiar item. It is precisely this type of negative correlation between estimates of familiarity and recollection which formed the basis of the Curran and Hintzman (1997, see below) critique of the independence assumption that is fundamental to the procedure.

An additional finding from Cermak, et al.'s use of process dissociation is that increasing the number of study trials appeared to increase the reliance of the amnesics upon recollective processes, while increasing the nonamnesics' reliance upon familiarity (1993, Experiment 2). Again, findings like these appear to provide more refined evidence about the processes underlying memory than provided by research relying only upon the direct/indirect distinction.

121 4.3 Process Dissociation: Critique and Review

While the process dissociation procedure has come to be regarded

as a creative and useful methodological development, there has been some

concern regarding the conceptual and procedural neatness of the solutions

offered by process dissociation procedures, and an apparent circularity in the

logic surrounding the dissociation of conscious and unconscious

mechanisms.

Mulligan and Hirshman (1997) identify four main themes to the

criticisms of process dissociation.

Lack of definitional clarity.

Many authors comment upon an apparent looseness of definitions

and operationalisation (Joordens & Merikle, 1993, Richardson-Kiavehn,

Gardiner & Java, 1994). Across the range of publications by Jacoby and co­

workers using process dissociation procedures, the words 'familiarity',

'automatic' and 'unconscious' are used almost synonymously, as are

'recollection' 'intentional' and 'conscious'. Allusions are also made to

concepts like the Freudian subconscious (Jacoby, Lindsay & Toth, 1992) as if

they too are among the parameters estimated from the procedure. It has

been suggested that this very broad specification of 'conscious' and

'unconscious' processes is neither psychologically nor empirically

supportable.

Richardson-Kiavehn, Gardiner & Java (1994), identify occasions on which the intention to recall may not result in a recollectable trace of the encoding episode, as well as the converse in which automatic retrieval may

122 produce conscious awareness. Thus they suggest that, contrary to the assumptions of process dissociation procedures, recollective processes are not necessarily conscious and automatic processes are not necessarily unconscious.

Similarly, Dodson and Johnson (1996) approach process dissociation from the perspective of Johnson's (Johnson, Hashtroudi & Lindsay, 1993,

Johnson & Hirst, 1993) source-monitoring framework, which argues that familiarity and recollection differ on a continuum related to specificity of source awareness, rather than qualitatively, as process dissociation procedures assume. They found (1996, Experiment 1) that manipulating the proportion of targets in the inclusion and exclusion tests interacted with divided and focussed attention in terms of their influence upon estimates of A, suggesting that familiarity is not synonymous with automaticity. However, in a study with similar implications, Gruppuso, Lindsay & Kelley (1997) reject the conclusions of Dodson and Johnson (1996), arguing that the familiarity estimate need not always be equated with automaticity, and may well be partially influenced by other experimental manipulations. For the purposes of the present study, the terms "recollection" and "familiarity" shall be used, and no presumption will be made regarding the relationship between "familiarity" as defined within the process dissociation paradigm and other conceptualisations of familiarity, automaticity and the unconscious.

Poor control of guessing and response sets.

Secondly, the original process-dissociation equations do not apply any correction for guessing. Indeed, as no truly new items are considered in

123 the equations, it is not possible to even assess the impact of differential guessing strategies on the inclusion and exclusion tasks. Mulligan and

Hirshman (1997) suggest that the relatively minor procedural variation of including new items in the recall tasks will permit correction for guessing and allow for the estimation of response biases between the two tasks. New items are included in all recognition and exclusion tasks in Experiments 5 and 6, and where there is evidence of response bias between the two tasks, the estimates will be corrected.

The independence assumption.

Process dissociation procedures assume independence and additivity of conscious and unconscious contributions to retrieval. It should not be conceptually possible, therefore, for retrieval in an exclusion condition to consistently exceed retrieval of the same items in an inclusion condition, since the sum of two positive components cannot be less than the value of the smaller component. After applying the process estimate equations, such an outcome would yield a negative estimate of the contribution of conscious recollection to recognition.

Even if one accepts independence as a working assumption within process dissociation, it is not clear whether apparent violations of this assumption are to be regarded as procedural failures (e.g. a change in response bias between tasks, Jacoby et al., 1993), empirical discoveries of the nondissociable nature of candidate mechanisms, or challenges to the empirical status of the process dissociation method itself (Curran & Hintzman,

1995).

124 For example, Debner and Jacoby (1994) explicitly endeavour to

investigate "variables which would produce dissociations in the estimated

effect of conscious and unconscious processes" (p307), and acknowledge

that there is an apparent circularity in this. They claim to avoid this circularity

by having chosen variables which are likely on empirical and theoretical

grounds to produce such dissociations. This defence does not solve the

apparently tautological nature of the project. Indeed it highlights the

conceptual and theoretical problems which would arise if variables which

could be reasonably expected to yield process dissociations failed to do so.

Curran and Hintzman (1995) describe a clearcut violation of the

independence assumption (correlations between the R and A terms in 5

experiments), which could still yield face valid though artefactual 'process

estimates'. Using inclusion and exclusion stem completion tasks, they found

that participants' response strategies led them to reduce their reliance upon

automatic processing as study time increased. Curran and Hintzman

conclude that the process dissociation procedure may not yield any 'purer'

estimates than the direct and indirect tasks Jacoby sought to replace:

Just as the results of traditional memory tasks may be criticised for reflecting a mixture of automatic and consciously controlled processes, the process- dissociation procedure may produce ambiguous results because of unknown violations of independence and contamination by alternative strategies. (1995, p546)

in a series of papers representing a dialogue between Jacoby and others (Jacoby, Begg & Toth, 1997, Jacoby & Shrout, 1997) and Hintzman and Curran (Hintzman & Curran, 1997, Curran & Hintzman, 1997), Jacoby

125 argues that Hintzman and Curran's artefactual dissociations are not the result of a violation of the independence assumption, but of their inclusion of participants who had null retrieval in the exclusion condition. These participants had been excluded by Jacoby, et al. (1993), because, as Jacoby, et al. (1997) note, the likelihood of zero false alarms in exclusion increases under conditions where recognition is optimised. Hence the rate of null exclusion performances is a function of recognition overall, yielding an apparent violation of independence arising from floor effects in exclusion.

This response echoes the comments of Debner and Jacoby (1993) described above. It is not clear whether Jacoby et al (1997) are merely noting that Curran and Hintzman have misconceived the estimation procedure and have therefore erroneously claimed to have violated the independence assumption, or if they are arguing that, at a more fundamental level, it is impossible to violate this assumption in a properly designed task. This argument becomes the focus of the Jacoby & Shrout (1997) and Hintzman &

Curran (1997) papers.

In a study with similar implications for the empirical status of process dissociation, Ratcliff, Van Zandt and McKoon (1995) generated pseudodata using an established single process model of recognition (SAM, Gillund &

Shiffrin, 1984) and subjected it to process dissociation procedures. They found that even when the data were in fact produced by a single process, process dissociation yielded results similar to those supposedly supporting a dual-process model obtained by Yonelinas (1994) hence:

126 The conclusion from this demonstration is that the estimates given by process dissociation are valid only under process dissociation's assumptions. Process dissociation equations have two parameters (the probability of recollection and the probability of familiarity being above a criterion}, and the equations are applied to only two data points in each experimental condition. This means that the method will always produce estimates of two components, even if the data were in fact generated from a single process. (1995, p359)

The theoretical implications of this debate should be kept separate from the procedural implications. At a theoretical level, the evidence that process dissociation 'dissociates' processes generated from a single process model significantly undermines the falsifiability of any claim that two processes MUST underpin recognition memory performance. However, as the above discussion indicates, the extent to which Jacoby would make this claim remains unclear. As a procedure, process dissociation appears to separate familiarity-based and recollective components at least as well as other available methodologies, and is based upon a more compelling argument than task-level 'dissociations'. Notwithstanding the above theoretical concerns, process dissociation is the most appropriate paradigm if one presumes that a dual process account is applicable to the specific memory phenomena under investigation.

Equivalence of inclusion and exclusion tasks.

A final group of criticisms of process dissociation addresses the assumption that the inclusion and exclusion tasks are identical in all but the procedurally crucial instruction concerning the treatment of old items, and that the contribution of automatic and recollective processes is not systematically

127 different between the two retrieval tasks. Clearly if a case can be made that the tasks differ in terms of conscious or unconscious cognitive components, difficulty or strategy use, the process estimates cannot be regarded as anything more than the arbitrary subtraction of performance on one retrieval task from that on another. It is essential to the logic of the procedure that the tasks are psychologically equivalent, yet the methodology itself has no procedure for establishing this equivalence.

4. 4 Alternative conceptualisations of process dissociation

Many of the above critics of process dissociation procedures endorse the opposition of inclusion and exclusion tasks, but propose alternative process estimation formulae based upon assumptions different from those used by Jacoby and colleagues.

Exclusivity Model.

Prior to Jacoby's (1991) formal statement of the methods of process dissociation, Jones (1987) presented a model at the other extreme to the independence model- the exclusivity model in which no overlap of conscious an unconscious processes is permitted. Jones argued that this model had much to commend it, at least as a parsimonious heuristic, and is neither more nor less conceptually appealing than any other presumption about the relationship between conscious and unconscious memory processes.

Redundancy Model

Joordens and Merikle (1993) contrast Jacoby's independence model with a redundancy model, in which conscious processes are assumed to be

128 always accompanied by correlated unconscious processes. Thus on all trials

where a conscious influence is present, there is also an unconscious

contribution. The model contains redundancy in that, although unconscious

processes can occur in isolation from conscious ones, conscious processes

cannot occur in isolation from unconscious ones. This assumption does not

alter the estimates of the R term from that defined above. However, as an

automatic influence is assumed to exist whenever recognition-based retrieval

is possible, the redundancy model does not separately estimate the

contribution of automatic processes to recognition. Recognition is always

accompanied by automatic, unconscious processes, and less often by

attendant conscious recollection. As automatic processes always underlie

recognition performance, under the redundancy model Equation 1 (p.1 09)

above becomes;

Inclusion =A (5)

As would be expected, the redundancy assumption does not alter

the estimates derived for the R term, but substantially influences the

magnitude of the estimate of the A parameter.

Joordens and Merikle (1993) used process estimates derived from

the redundancy model as the basis of a reanalysis of the results obtained by

Jacoby et al. (1993) - in which divided attention altered the contribution of

recollective processes to stem completion, but was independent of familiarity

(Jacoby et al. 1993 Experiment 1). As the redundancy model does not

assume complete independence of conscious and unconscious processes, this reanalysis suggested that divided attention reduced both conscious and

129 unconscious contributions to the task.

While not necessarily asserting the redundancy model is more appealing than the original independence model, Joordens and Merikle

(1993) do suggest that there is no compelling empirical evidence that it is Jess satisfactory. They argue that the independence assumption is one of a number of arbitrary determinations made in developing process dissociation procedures.

Merikle has argued elsewhere that there is little value in dissociating conscious from unconscious processes, as 'consciousness' probably lies upon a continuum, and takes on a range of qualitative and quantitative attributes depending upon the task and participant characteristics (Reingold and Merikle, 1988, 1990).

Integrating the independence. exclusivity and redundancy models.

An attempt to integrate the three models is provided by Buchner,

Erdfelder and Vaterrodt-PIOnnecke (1995) who depict the three models as variants upon a single processing tree, differing only in the assumed value for the conditional probability of an item being familiar given it has been recollected.

From this perspective they argue that all three models agree regarding the estimation of the R value (Equation 3 above), but differ markedly in estimates of the A term. However, although the A term differs between models, the conditional probability that an item is familiar given it was not recalled is common to all three models, and can thus be estimated.

Cowan and Stadler (1996) agree with Buchner et al. (1993) that

130 there may be no mathematical need to determine which model applies to a given data set. However, they suggest that the independence, redundancy and exclusivity models are so divergent in their psychological implications, that they ought to be empirically distinguishable. They develop the case that only in the independence model is the overlap between conscious and unconscious processes free to vary between tasks and situations. In the redundancy model, the overlap is assumed to be complete in at least the case of recollection, ie. there cannot be conscious retrieval without attendant unconscious processes. In the exclusivity model, there can be no overlap in any task. Cowan and Stadler (1996) classify the redundancy and exclusivity models as fixed ratio models, along with all theoretically possible models which fix the overlap between conscious and unconscious processes at any other arbitrary value. The relationship between the R estimate from a given model and the observed ratio of familiarity-based processes to recollection is defined within the model. Models can therefore be defined in terms of the slope of the linear relationship between these two variables - a relationship referred to as an estimate line by Cowan and Stadler.

By plotting estimate lines from a range of fixed ratio models against data obtained in a number of process dissociation studies, Cowan and

Stadler (1996) conclude that Jacoby's independence model better predicts the intercept between conditions (eg divided versus focussed attention, read versus anagram encoding) and the estimate line than does any single fixed ratio model. While this does not eliminate the possibility of there being a range of task-and participant specific fixed-ratio models, Cowan and Stadler

131 argue that the independence model is a sufficient heuristic in the absence of overwhelming evidence for any particular fixed ratio model.

Experiments 5 and 6 will use the typical (Jacoby) process estimate equations for all empirical and statistical analyses, as well as for the bulk of the theoretical interpretation of the findings. Thus the present experiments are based upon an operational presumption of the independence of the conscious and unconscious contributions to recall. However, the results will be discussed with reference to the estimates which would have been obtained under the redundancy model estimation procedures (Chapter 6).

132 Chapter 5 Experiments 5 and 6

Reingold and Goshen-Gottstein (1996) applied process-dissociation procedures to investigate the mechanisms contributing to the associative priming of unrelated word pairs. "Associative priming" refers to the extent to which retrieval is facilitated when a word is presented with its prior, arbitrarily determined pair. This is contrasted with the presentation of the word without its pair. As such, the direct effects of repetition are not calculated, but the contribution of the prior word context can be estimated.

Graf and others (Graf and Schacter, 1985, 1987, Schacter and Graf,

1989) have found the stem completion task is sensitive to associative priming effects, such that reinstatement of the original arbitrary pairing facilitates word retrieval. Reingold and Goshen-Gottstein (1996) suggested that the A term remained relatively invariant across the manipulation of elaborative versus repetition encoding, and the effect of encoding strategy on stem completion was largely attributable to the activity of conscious recollective processes.

Experiment 5 is similarly motivated. It investigates the extent to which the effects of simple repetition and response repetition in lexical decision obtained in Experiments 3 and 4 may be attributable to familiarity and recollection-based retrieval processes.

As outlined in Chapter 1, lexical, episodic, and multiple locus models can provide similar accounts of repetition and frequency effects, and therefore all are broadly consistent with the results of Experiment 4. Nonetheless, adopting a paradigm which separates the effects of prior presentation alone

133 from those of prior classification does permit more explicit investigation of the

two priming effects. Experiments 3 and 4 were somewhat constrained by he

use of reaction time as the sole dependent variable. This had the effect of

only permitting a partial separation repetition without a response from

response-based processes, as reaction time can only be measured if a

response is made to at least one presentation of the item. While response

latencies are recorded in Experiments 5 and 6, retrieval of items for which no

response was required during the priming task is also assessed in later

memory tasks. Furthermore, the use of process dissociation procedures in

the delayed memqry test for items encoded in the context of repetition priming

will permit more direct evaluation of the contribution of the repetition, lexicality

and frequency variables to familiarity and recollection estimates, highlighting

the contribution of pre-and intra-experimental familiarity to retrieval.

5. 1 Experiment 5

Experiment 5 includes a modified replication of the lexical decision

paradigm of the previous experiments that eliminates a number of

confounding features that obscured clear interpretation of the differential

effects of prior presentation with and without a response requirement. in

Experiment 4, items were 'tagged' for response by appearing in capital letters;

and repetitions of unclassified stimuli were presented immediately while

repetitions of a classified stimulus followed two intervening items. Thus,

comparisons of repetitions following classified and unclassified initial

presentations were confounded with differences in both the perceptual similarity of the two presentations and the lag between them. The different 134 patterns of priming in these two conditions may therefore be due to the response requirement, the variation in spacing of repetitions, the case shift or any combination of these.

In Experiments 5 and 6 all stimuli were presented in the same (upper) case, and those requiring a response marked by being surrounded by << >> symbols. Although this marker is still a contextual feature that differs between classified and unclassified items, this marking method reduces differences in the degree of perceptual similarity across repetition conditions. A lag of two intervening items between repetitions was consistently used for both types of repetition.

In addition to these modifications to the lexical decision task,

Experiments 5 and 6 include tests of memory for the items initially encountered and repeated in a lexical decision task. At a general level, the memory tests provide a measure of the transfer of repetition effects across tasks. If the nonword effects arising from prior classification in Experiment 5 are due to the formation of an episodic representation of the nonword, this representation should survive the transfer to another task. If, however, the nonword facilitation observed in Experiment 5 reflects the learning of a specific classification response to the nonword stimulus, there should be no transfer of familiarity to a task with different response requirements.

To provide further specification of the basis of repetition effects, performance in a standard recognition memory test is compared with a recognition exclusion memory test in which participants are instructed to explicitly reject items that they can consciously remember being presented in

135 the lexical decision task. Comparisons of the effects of repetition on the two memory tasks allow conscious episodic influences to be isolated. If the additional facilitation found for low frequency words in Experiment 4 is due to the acquisition of a conscious episodic trace of the item, it may be possible to index this trace using process dissociation procedures.

The procedure required participants to study a short list of auditorily presented words and nonwords that served as the intentional learning list for participants in the exclusion task. They were then presented with the lexical decision task. After a lag of 20 minutes, participants completed a recognition or recognition exclusion task containing half of the items presented in the study tasks.

An additional indirect memory test is used in Experiment 5. Cowan and Stadler (1996) suggest that the use of a 'traditional' indirect memory test of the same items contrasted in inclusion and exclusion conditions allows estimation of unconscious, familiarity-based process independently of the process estimates themselves. If this task were"... an indirect task that one knew was not influenced by conscious processes ... " (Cowan and Stadler,

1996, p199), it may permit determination of the specific model pertaining to the class of items used (See Chapter 4). A perceptual identification task was included for this purpose in Experiment 5.

As items for which no response had been made in the priming trial can now become the subject of memory testing, the description of conditions that was used for experiments 3 and 4 needs to be modified. Henceforth the notation NPXR will be used to describe the repetition conditions, where N is

136 the number of presentations of the stimulus in the priming task and X is the number of responses required in the priming task. The condition previously described as "simple repetition" (two presentations with a response to only the second) would thus become 2P1 R , while response repetition would be

2P2R. Items that were new in the priming task (Single presentation, single response), will be referred to as 1P1 R items, as the term "new" is misleading in the context of the memory tasks. Finally, items may be presented once or twice in the priming task without response. These conditions shall be referred to as 1POR and 2POR respectively.

Method.

Design. In the lexical decision task, high frequency and low frequency words and nonwords were presented once or twice, with responses required to a single presentation, the second of two presentations, or to both of two presentations. The lexical decision task was therefore treated as a 3 X

3 repeated measures design.

Half of the critical words from the lexical decision task were then tested using a perceptual identification task, and following this participants performed either recognition or exclusion recognition task on the remaining half of the items. In addition to the three repetition conditions of the lexical decision task, it was also possible to test participants' recall for items that had been presented in the lexical decision task without requiring a response.

Each memory task was therefore analysed as a 3 (high frequency words, low frequency words, nonwords) X 5 (1 POR, 2POR, 1P1 R, 2P1 R, 2P2R) repeated

137 measures design. As participants performed each memory task on only half

of the presented items, there were two counterbalanced lists that were treated

as a between groups factor in analyses of each memory task.

Participants: The participants were 31 volunteers sampled from the

same population as for Experiments 1 to 4. All participants completed the

lexical decision and perceptual identification tasks. Sixteen completed

recognition and fifteen recognition exclusion.

Stimuli. A list of 20 mid frequency words and 20 nonwords was

generated to serve as an initial auditory study list for the subsequent

recognition exclusion task. This list is used as the target list for the exclusion

condition, with participants instructed to retrieve items from the auditory list

while excluding those from the lexical decision task. Retrieval of the study

items is nonetheless the dependent variable, so the attributes of the auditory

list items are not procedurally relevant.

Lexical Decision: A new pool of stimuli comprising 50 high frequency

words, 50 low frequency words and 100 nonwords was derived from the MRC

Psycholinguistic Database (Coltheart, 1981). Words were constrained to be

single or two syllable nouns between 4 and 6 letters long, with concreteness

ratings between 200 and 600 and imageability ratings between 300 and 600.

Pronounceable nonpseudohomophonic nonwords between 4 and 6 letters

were selected from a pool computer-generated to approximate the bigram distribution of English. A pool of 200 additional mid frequency words and 200

nonwords served as fillers. Critical items were distributed among the list of fillers in a similar fashion to Experiments 3 and 4, with the exception that

138 there were always two intervening items between stimulus repetitions.

Immediately following the lexical decision task, participants completed the perceptual identification task for half of the critical items. They then performed recognition or recognition exclusion for the other half of the critical items. Lists were counterbalanced so that all items were tested in perceptual identification, recognition and exclusion tasks.

Perceptual identification: Two lists were generated from the 200 critical items of the lexical decision task, each comprising half the items from the each of the original presentation conditions. Participants were tested on one of these two lists. Five further lists from the same pool were generated as 'calibration' lists and used to establish a presentation duration for each participant in the identification task. Each cal:bration list comprised five high frequency words, five low frequency words and ten nonwords. An additional set of 20 mid frequency words and 20 further nonwords were used as 'new' items in the perceptual identification task.

Recognition and Recognition Exclusion: The 100 critical items not used in the perceptual identification task were included in either the inclusion or exclusion recognition tasks. A further 50 words and 50 nonwords were generated as above to serve as distractors in both lists. All items were tested in both recognition and exclusion conditions. The two recognition lists thus comprised 100 critical items and 100 matched foils, as well as the auditory study items.

139 Procedure. Participants were informed that the experiment was an

investigation of memory for real and nonsense words and had four parts.

Firstly, they were to learn an auditory list of real and nonsense words for a

later memory tests. Following this they would complete word decision and

perception tasks intended to create a delay, before their memory testing for

the original items. They were then presented with the 40 items of the auditory

study list via headphones. Immediately following the auditory study list,

participants were told that to complete a word decision task to strings of

letters presented in the middle of the screen. They were only to respond to

items surrounded by diamond brackets, and to press the 'Yes' button if the

letters formed a word, and the 'No' button if they did not. Twenty practice

items were presented, followed by the main set of stimuli in a single block

randomised for order. Stimulus duration and timing was as for Experiment 3.

The perceptual identification task immediately followed the lexical

decision task . It was described as a measure of 'perceptual sensitivity to

words'. They were told they would see real and nonsense words presented

for a very brief period of time, and they were to report whatever they could

see of the item.

These instructions were followed by the five 'calibration' lists described above. These were presented in random order at durations of 14,

28, 34,56 and 72 milliseconds. After the presentation of all five lists, a single exposure was chosen for all items in the perceptual identification task. This exposure was chosen according to the criteria that participants must have been able to successfully report at least two of the ten nonwords and not

140 more than three of the five high frequency words at this duration in the calibration tasks. For all but 2 participants, these criteria were satisfied by a

56 millisecond presentation. This was not intended as an attempt to estimate a psychophysical threshold, merely to ensure that for each participant a duration could be found which was not confounded for any class of items by obvious ceiling or floor effects.

After a presentation duration had been selected, participants were presented with the perceptual identification items and asked to identify each word or nonword. Guessing was discouraged. Learning of critical items was defined as the difference between retrieval of critical and new items.

The Perceptual identification task took approximately 20 minutes, after which half the participants completed the recognition and half the recognition exclusion task. Participants in the Recognition task were told that the instructions to remember only the items from the auditory list had been a deception, and they were in fact going to be tested on items from the word decision task. They were to read the items appearing on the screen and to press the 'yes' key if they thought the items had been presented in the decision task, and the 'no' key to all other items. Items for recognition were presented one at a time, and remained on the screen until a response was registered.

The recognition exclusion condition differed only in the instructions for the memory task. Participants were told that, as expected, they were to be tested on their memory for items from the first auditory list. They were informed that the recognition task included some distractor items from the

141 word decision task, but no items from the auditory Jist had been presented in

any other task in the experiment. Therefore if they remembered an item as

having come from the lexical decision task, they knew that it had not been

presented in the auditory study task, and should therefore press the 'no' key.

The items were then presented as described for the recognition task.

Results.

Lexical Decision. Reaction times and error rates for the nine lexical decision conditions are presented in Figure 4.

950 •·--.---- ..... -- ... -.-----.- .. ·• 900 .. \ ...... " ...... '•, '• 850 ...... ······ ...... '• 7ii ...... •, g 800 ...... •, ·..... Cl) ...... _ E .... __ +I ..... 750 - -High Freque c ..... 0 ...... _.... _ 'iii -- _ .. _Low Freque ·c:; cQ) 700 -- .. -- •-• Nonwords i\i u ')( Cl) 650 ..J

600

550.

500 New Simple Repetition Response Repetition Repetition Condition

Figure 4: Experiment 5. Mean Reaction Times (milliseconds) for high frequency words, low frequency words and nonwords. P = number of presentations of the stimulus word, R = number of responses required.

142 Words were classified more quickly than nonwords [F(1 ,30) = 48.63]

and high frequency words more quickly than low frequency words [F(1 ,30) =

70.85] . Lexical decision speed was significantly facilitated by repetition of the

stimulus alone [IP1 R vs 2P1 R: F(1 ,30) = 64.55] and by repetition of a

previously classified stimulus [2P1 R vs 2P2R: F(1 ,30) = 49.42].

As in Experiment 4, lexical status interacted with number of

presentations. Words were significantly facilitated by repetition of the

stimulus alone while nonwords were not [F (1 ,30) =11.50]. However, both

words and nonwords showed significant repetition priming when the initial

presentation had required classification [2P1 R vs 2P2R F(1 ,30) = 14.377,

32.51 and 44.76 for High frequency, Low frequency and Nonwords

respectively]

The repetition effect due to unclassified re-presentation of a stimulus

was greater for low than high frequency words [IP1 R vs 2P1 R: F(1 ,30) = 8.61]

although both low frequency and high frequency words benefited significantly from prior presentation [1 P1 R vs 2P1 R, F(1 ,30 = 5.41, F (1 ,30) = 45.09, high

and low frequency respectively, both p < 0. 05]. When the item had been

presented twice, the interaction between number of responses and frequency was not significant [2P1 R vs 2P2R. F(1 ,30) = 1.30, ns]. Nonwords did not benefit from prior presentation alone [F<1].

The error data for the lexical decision task of Experiment 5 is shown in Table 7

143 Table 7: Experiment 5: Mean percentage errors for high frequency words, low frequency words and nonwords. P = number of presentations of the stimulus word, R =number of responses required. Standard deviation in parentheses

Repetition Condition 1P1R 2P1R 2P2R High 0.96 2.90 1.29 Frequency (3.00) (4.61) (3.41) Low 11.61 6.13 6.45 Frequency (12.14) (1 0.54) (9.15) Nonwords 7.42 7.42 3.38 (8.15) (1 0.40) (5.54)

The analysis of error rates revealed significant effects of frequency

[F(1,30)= 15.54], number of presentations [IP1 R vs 2P1 R : F(1,30)= 7.37] and number of responses [2P1 R vs 2P2R : F(1,30) = 10.58]. Frequency and number of responses interacted significantly [F(1,30) = 14.97], with low frequency words showing greater benefit from a prior classification decision.

The differences in error rate between words and nonwords were not significant [F<1], nor were interactions between lexical status and number of presentations [F(1,30)=3.97, ns], or number of responses [F < 1].

Perceptual identification. Unlike for lexical decision, it is possible to evaluate memory for words which did not require a response in the lexical decision task. Table 8 presents the proportional degree of facilitation gained by items presented in each condition of the lexical decision task over items newly presented in the identification task.

144 Table 8 Experiment 5. Proportional gain in probability of correct perceptual identification arising from prior exposure in each presentation condition of the lexical decision task. Standard deviations in parentheses.

Repetition Condition

1POR 2POR 1P1R 2P1R 2P2R

High Facilitation from 0.197 0.210 0.251 0.245 0.293 Frequency prior exposure (0.219) (0.279) (0.253) (0.260) (0.202)

Low Facilitation from 0.103 0.103 0.221 0.221 0.303 Frequency prior exposure. (0.273) (0.237) (0.258) (0.272) (0.268)

Nonwords Facilitation from 0.124 0.145 0.228 0.197 0.172 prior exposure (0.165) (0.207) (0.203) (0.164) (0.194)

145 As is evident from Table 8, participants showed relatively little benefit on the identification task from prior presentation for any presentation condition or item type. There were no significant main effects for lexical status (F(1 ,27)

=1.52) or word frequency (F(1 ,27)= 1.14). Items which had required a classification response in the lexical decision task were more likely to be identified than words which had not (no response versus any response,

F(1 ,27) = 30.84), but the addition of a second response did not result in further improvement (1 response versus two responses, F(1 ,27)= 1.57).

Responding differentially influenced low and high frequency words (response versus no response X frequency; F(1 ,27)= 7.28). High frequency words were more likely than low frequency words to be identified as the result of prior presentation alone, whereas high and low frequency words benefited equally from a prior classified presentation.

Recognition. As the process estimates were based upon item analyses, all results for recognition, exclusion and process estimates are based upon item, rather than subject analyses. They therefore reflect the likelihood of an item being retrieved in the two conditions averaged across participants.

All analyses were conducted using both participant and item data.

The pattern of results did not change between the two analyses. The item data proved the most conservative- no result was significant by items that was not significant by participants. One finding, which had been significant in the participant data was not significant in the item data. In order for the reported data and the Analysis of Variance results to remain comparable, only item

146 data will be reported upon.

The proportion of items from each repetition condition of the lexical

decision task that were correctly identified as "old" in the recognition task is

shown in Table 9. Table 9 also presents the likelihood of a critical item being

retrieved despite the exclusion instructions in the recognition exclusion task.

As a check on absolute recognition accuracy, the endorsement rate

for critical items from the study task was compared with that for new distractor

items. The rate of false positive identification of new items was 22.5%. The

false positive rate for new items did not differ significantly between classes of

items (F<1 ), suggesting that there was no differential response bias for high

frequency words, low frequency words or nonwords. Therefore, no correction

to the recognition memory data was required. Overall recognition accuracy

was significantly higher than the false positive rate for new items [F(1,381) =

165.92].

Words were recognised more accurately than nonwords [F (1,381) =

146.77] but there was no overall effect of word frequency [F<1 ]. Recognition

accuracy increased with number of presentations [1 vs 2 presentations, F

(1,381)= 9.05], and with number of responses [0 vs 1 response, F(1,381) =

99.73, 1 vs 2 responses, F (1,381) = 5.03].

A significant interaction between whether a classification had been made and lexical status [F{1,381) =10.16] demonstrated that the component of the repetition effect derived from a classification decision was more marked for words than nonwords.

147 Table 9. Experiment 5. Percentage of critical items recalled from each presentation condition in the recognition and exclusion recognition tasks.

Repetition Condition

1POR 2POR 1P1R 2P1R 2P2R

High Recognition 43.33 30.45 58.35 61.11 73.23 Frequency Exclusion 31.45 28.60 28.60 30.02 21.01

Low Recognition 24.44 42.78 68.34 72.22 70.55 Frequency Exclusion 14.30 24.31 21.44 20.02 22.88

Nonwords Recognition 28.59 26.94 43.04 42.77 46.94

Exclusion 24.30 20.73 24.30 27.16 18.58

148 Nonword recognition was not facilitated by repeated presentation [F <

1], but improved significantly if a classification response had been required in the lexical decision task [0 vs 1 response, F(1,381)= 18.83]. A second classification response had no further impact on nonword recognition [ 1 vs 2 responses, F < 1]. High and low frequency words were differently affected by the nature of the prior experience with the stimulus. Low but not high frequency words benefited from being presented twice rather than once without a response being made [1 POR vs 2POR, F(1 ,381) = 5.09 and 2.49, ns for low and high frequency words respectively]. Conversely, high but not low frequency words were recognised more accurately when they had been classified twice rather than once in the lexical decision task yielding an interaction between frequency and whether one or two classification decisions had been made [F(1 ,381) = 4.27].

Recognition Exclusion. Table 9 also shows the probability of endorsing items from each condition of the lexical decision task in the recognition exclusion task in which participants were instructed to reject these items. The values therefore represent the probability of false alarms to items from the lexical decision task.

Endorsement rates for items from the auditory study list (29.85%) were higher than for both critical items from the lexical decision task (23.84%)

[F(1 ,381)= 60.21] and new distractor items (21.66%) [F(1 ,381)= 43.88]. This indicates that participants were following the exclusion instructions by attempting to endorse items from the learn list. However, the overall false positive rate for new items did not differ from that for items from the lexical

149 decision task [F<1] indicating that the overall intrusion rate for lexical decision items was only at chance level. Notwithstanding the Jack of general intrusion of lexical decision items into the retrieval task, comparisons can still be made of relative rates of intrusion as a function of repetition history.

In the exclusion data, there were no effects of lexicality, number of presentations, prior classification, or repeated classification [All Fs < 2.49].

High frequency words were significantly more likely to be erroneously endorsed than low frequency words [F(1 ,381) = 4.11].

Process estimates. As described above, Jacoby (1991) suggests that subtracting the probability of an item being recalled under exclusion conditions from hit rate in standard recognition conditions provides an estimate of the unique contribution of conscious recollective processes to recognition memory performance. Equation 3 can also be used to estimate the unique contribution of automatic, or unconscious processes. Table 10 provides the estimated values of the parameters for the present Experiment.

Recollection. As may have been predicted from the relative absence of significant effects in the recognition exclusion task, the profile of the

'recollection' results resembles that for recognition. Word frequency did not influence the contribution of recollection to recall [F(1 ,381) = 2.90, ns]. Words were estimated to have a higher contribution of conscious recollection to recognition than were nonwords [F (1,381) =22.67].

The recollective component of recall was enhanced by repeated presentation of items [1 v 2 presentations , F(1 ,381) = 5.72] .

150 Table 10: Experiment 5: Process Estimates (Jacoby, 1991). Contribution of recollection and familiarity- based processes to the probability of retrieval of items in each condition. P= number of presentations. R = number of responses

Repetition Condition

1POR 2POR 1P1R 2P1R 2P2R

High Frequency Recollection 0.119 0.019 0.297 0.311 0.532

Familiarity 0.322 0.290 0.433 0.456 0.582*

Low Frequency Recollection 0.101 0.185 0.469 0.522 0.477

Familiarity 0.151 0.280 0.331 0.407 0.468

Nonwords Recollection 0.043 0.062 0.187 0.156 0.284

Familiarity 0.230 0.225 0.271 0.302 0.240

*One item excluded due to a null denominator in familiarity estimate, see footnote.

152 Classification of an item significantly increased the recollective

components of subsequent recognition [no response vs 1 response,

F(1 ,381)= 57.03], as did repetition of the classification response [1 vs 2

responses, F(1 ,381) =6.68].

The interaction between lexical status and response was significant, with nonwords showing greater facilitation than words from a single classification. [F(1 ,381) = 6.80].

A significant interaction between frequency and number of classification responses [F(1,381) = 5.31] can be seen in Table 13 as an increase in the recollective component of retrieval for high frequency words between 1 and 2 responses for words repeated twice, but a decrease in recollection for low frequency words between the same conditions (2P1 R and

2P2R).

Familiarity: As discussed in Chapter 4, the computation of the familiarity (or U or A) parameter is model-bound, unlike the computation if the

R parameter2. In the present data the derived recollection and familiarity terms were not significantly correlated (r= 0.061). This finding does not

2 The estimation of the A term is further complicated in the present data by the observation that one item in the high frequency 2P2R condition was recognised with 100% accuracy and never falsely endorsed in the exclusion task. While this finding can be meaningfully interpreted in terms of the recollection estimates- the words were retrieved entirely through conscious recall - the application of Equation 3 above yields a zero denominator for 'familiarity' under such circumstances, rendering the term inestimable. A similar problem arises with two items in Experiment 6. Jacoby, Toth and Yonelinas exclude all participants with perfect recollection, suggesting that this reduces the chance of spurious correlations between estimates. In the present Experiments 5 and 6, items with perfect recognition and zero intrusion in exclusion have been eliminated from the familiarity estimates only. It is felt that the problem of a zero denominator does not reflect an exceptional property of the item, rather an artefact of the computation of a single parameter. The item is therefore removed from the parameter it directly influences, rather than from the recognition, exclusion and recollection data in which it

153 unequivocally support the independence assumption as Joordens and

Merikle, 1993, demonstrate that the assumption is intrinsic to the computation of the A term, and hence cannot be tested using empirically obtained estimates of that term. Nonetheless, it does not suggest any substantial violation of the independence assumption in the present data.

Words yielded higher familiarity estimates than nonwords [F(1,380)=

21.21], however in contrast to the recollection estimates, there was a significant word frequency effect in the familiarity data [F(1,380) = 6.176], with the proportion of retrieval attributed to familiarity greater for high than low frequency words in all conditions. Number of presentations and making a classification response also increased the proportion of retrieval attributable to 'familiarity' processes [F(1,380)= 6.70, F(1,380) = 25.01, respectively].

Having made a classification response in the lexical decision task interacted with lexicality, with words showing greater benefit from a prior classification decision than nonwords [F(1,380) = 7.35].

Another difference between the recollection and familiarity results is that the latter estimate was not affected by the number of responses made to the stimulus [F (1,380)= 2.91,ns] and number of responses did not interact with word frequency [F < 1]. However, the effect of multiple response was different for words and nonwords [F(1 ,380= 5.51]. While words continued to improve between 1 and 2 responses, the contribution of familiarity to nonword retrieval after two responses was lower than when only one response had

does not pose a problem.

154 been made.

Discussion

Repetition influenced lexical decision, perceptual identification, recognition and recognition exclusion tasks, as well as the computed values representing 'recollection' and familiarity.

Consistent with the results of Experiments 3 and 4, different mechanisms appear to contribute to the influence of repetition on both within task priming and longer-term memory tasks for high frequency and low frequency words and nonwords. The results of Experiment 5 shed further light on the nature of these mechanisms.

Lexical Decision Task

Lexicality: As in Experiment 3, repetition priming of nonword lexical decisions only occurred when the item was classified on its initial presentation. The recognition data demonstrate that the influence of this type of repetition is still evident at least 20 minutes following the initial presentation of the item and within a different task. The increased error rate observed in

Experiment 1 for nonwords repeated without a previous classification was not reproduced in the present experiment in lexical decision errors, latency, or subsequent retrieval. Thus, whatever mechanism was responsible for that result in Experiment 1 does not appear to survive two intervening items, and does not influence memory performance.

Frequency. Also paralleling the results of the earlier experiment, lexical decisions to both high and low frequency words were facilitated by

155 repetition whether or not the item was classified on its initial presentation.

However, in the memory tasks, repetition without classification only enhanced retrieval of low frequency words. By contrast, repetition of the classification response enhanced retrieval of high frequency but not low frequency words.

The comparison of performance under recognition and exclusion instructions helps clarify the latter finding. In general, a mirror effect (Glanzer

& Adams, 1985, 1990) was observed for high frequency words. Repeating the classification response to a high frequency word simultaneously improves overall hit rate for the items, while reducing their likelihood of being falsely endorsed as coming from another task. Overall, high frequency words were slightly more likely to be falsely endorsed as having come from the auditory study list than were low frequency words, suggesting that previous experiences with high frequency words are less likely to be recognised as having been part of a specific study episode than experiences with low frequency words. However, when the item had been classified in the lexical decision task, false alarm rates for high frequency words in the exclusion condition declined significantly, while hit rates for the same words significantly increased. This finding is reflected in the findings of the process estimates and suggests that classifying and/or responding to a high frequency word enhances the likelihood of explicitly recollecting the study episode, while no such effect is evident for low frequency words.

Mirror effects represent something of a paradox within the memory literature, as they seem to suggest both higher recollection (superior recognition performance) and lower familiarity (low false alarm rates) for the

156 'mirrored' items (Guttentag & Carroll, 1997). Any account expressed in terms of independent familiarity and recollective processes therefore has to resort to separate explanations of these two features of the mirror effect. The present mirror effect for high frequency words is particularly puzzling, since the effect is far more commonly obtained for low frequency words.

Explanations of the low frequency mirror effect typically present it as the resolution of a trade-off between baseline familiarity (frequency) and intra- experimental processing. Low frequency words are presumed to have lower baseline familiarity, but to yield a greater gain in familiarity as a result of intra- experimental presentation.

The WFE [word frequency effect] for false alarm rates can then be explained as a consequence of frequency-related differences in baseline rates of familiarity, whereas the WFE for hit rates is assumed to reflect frequency-related differences in the relative increments in familiarity that occur when an item is actually presented.

(Guttentag & Carroll, 1997, p 503)

However, the results from Experiment 5 suggest some modification of this argument. In the present results, the same conditions which eliminate any recognition superiority of low frequency over high frequency words (the second classification response) also produce an atypical high frequency mirror effect. This suggests that the mirror effect may be more attributable to intra-experimental processing requirements than to word frequency effects per se. This possibility is pursued further in the Discussion of Experiment 6.

157 Perceptual identification task

The results from the perceptual identification task are more difficult to interpret than those from the lexical decision and memory tasks. Paralleling the findings from the exclusion recognition tasl,, high frequency words yielded greater facilitation from prior presentation than low frequency words, but only if a response was made in the lexical decision task. Thus, the 'indirect' identification task appears to be sensitive to similar stimulus features as the exclusion task, suggesting that the two tasks operationalise similar aspects of retrieval. However with relatively low facilitation evident either task, it is difficult to precisely specify the mechanisms underpinning the common effects.

Process estimates.

The process estimates derived from the recognition and exclusion tasks illuminate the results of the recognition and exclusion tasks from which they are derived. In particular, the process estimate results suggest that the effect of lexicality evident in other tasks in the Experiment appear to be reflecting the recollectability of items, but not their familiarity, while word frequency exerts an influence upon both familiarity and recollection processes.

Experiment 5 also suggests that for nonwords, all changes in retrieval as a result of repetition were attributable to changes in the recollection, rather than the familiarity estimate. Perhaps surprisingly, given the novelty of nonwords, the estimates of familiarity for nonwords were not very low overall compared to words, but the estimates did not change as a result of either

158 repeated presentation or response. In contrast, both the familiarity and recollection estimates for words were influenced by the different types of repetition.

A final important implication of Experiment 5 arises from the interaction of frequency with number of responses in the recollection data.

Specifically, when no response or a single response had been made in the lexical decision task, low frequency words were more likely to be retrieved on the basis of recollective memory than high frequency words. However, this low frequency advantage in recollection was reversed when two classification decisions had been made. This result was observed only in the retrieval data.

Number of responses did not interact with word frequency 'on line' during the lexical decision task. Therefore it does not appear to reflect differential accessing and processing of high and low frequency words during study, but rather the influence of differential forgetting or retrieval strategies at the time of memory testing.

Thus Experiment 5 provides evidence that the recognition and exclusion tasks, and the process estimates derived from them, usefully dissociate a number of mechanisms serving memory for repeated items.

Both recollective and familiarity-based processes are influenced by the lexical status of the item, while familiarity alone shows a main effect for word frequency.

Broadly, the results appear to support a model which ascribes differential priming of words and nonwords to the influence of conscious retrieval process, while attributing frequency effects on word priming to a

159 combination of conscious and unconscious processes.

However, Experiments 3, 4 and 5 have utilised the lexical decision task as the incidental study paradigm. It could be argued that many of the effects observed in the present study arise from the particular classification decision being utilised at study. In Experiment 6, word naming is used as the study task rather than lexical decision.

5. 2 Experiment 6.

A critical outcome of Experiments 3,4 and 5 is that repetition effects for nonwords only occur when the stimulus must be classified on its initial presentation. Words, particularly of low frequency, show priming from simple presentation of a stimulus. As discussed in previous Chapters, differences between words and nonwords can imply that abstract representations do contribute to repetition priming effects for words.

Experiment 5 also suggested that lexicality effects were supported by recollective processes only, while word frequency appeared to impact upon both recollection and familiarity. But these conclusions are confounded somewhat by the fact that the lexical decision task was used to assess repetition priming in Experiments 3, 4 and 5 ,and as the incidental study task for subsequent memory testing in Experiment 5.

As mentioned in Chapter 1, Feustal, et al. (1983) suggested that the lexical decision task to repeated items comprises both response practice and memory processes. For words, these two contributions are complementary­ practice at pairing the "word" button with this combination of letters provides an extra benefit in addition to the memory- based contributions to priming. 160 However, for nonwords, the two mechanisms might work in opposition- any benefits of practice at pressing the 'nonword' key to this stimulus may be offset by the increasing familiarity of the item arising from previous encounters.

The error data from experiments 3 and 4 suggested that precisely this sort of tradeoff may occur for nonwords repeated in the present paradigm.

Indeed, a part of the motivation for Experiment 5 was to investigate the extent to which memory-based priming mechanisms- 'masked' by response mechanisms in the lexical decision task- might still provide a basis for retrieval in a subsequent memory task.

Experiment 5 did not suggest any residual learning of nonwords presented without response requirements in any of the three retrieval tasks used. However, it could be argued that the use of the lexical decision task as a study task, by drawing attention to lexical status, may amplify effects of lexicality on subsequent tasks. In particular, the impact of lexicality in recollection and familiarity estimates may arise from differential attention and processing of words and nonwords in the course of the study task. Lexicality effects on memory would be more adequately demonstrated if they arise following a study task which is not explicitly lexical.

Brown and Carr (1993, Experiment 1) directly compared the naming and lexical decision tasks in terms of the magnitude, nature and cross-task transfer of repetition priming. They found that naming was generally faster than lexical decisions. Of more importance to the present discussion, target task interacted with lexical status, with nonwords showing similar priming to

161 words in the naming task, but no facilitation in lexical decision. Brown and

Carr speculate that this difference might be attributable to processing differences between the two tasks, but as they used lexical decision and naming as both study and test tasks, it is impossible to interpret their findings regarding transfer independently of those of specific response requirements of the two tasks. Experiment 5 clarifies the latter issues. It yielded repetition effects for nonwords only under conditions where multiple responses were made. The memory data further failed to support the suggestion that the lack of nonword effects might be due to the cancelling out of memory effects by response requirements, since there was no evidence of any residual learning of non responded nonwords.

To evaluate whether the differential patterns of memory for repeated items observed for words and nonwords are due to the use of a lexical decision task at study, Experiment 6 employed the naming task as the initial study experience. Naming latency should not be subject to the same response confusion as lexical decision, since the naming task does not require a 'no' response to familiar items. Furthermore, naming does not require specific attention to lexicality. Therefore if the lexicality effects on retrieval in Experiment 5 are due in part to the attention paid to lexicality at study, then those effect might be reduced or eliminated by the use of the naming task.

162 Method

Design. Experiment 6 replaces the lexical decision task from

Experiment 5 with a speeded naming task. Items were shuffled within lists and reallocated to repetition conditions, but the design, instructions and items were otherwise the same as in Experiment 5.

Participants. Twenty-six undergraduate students from the same population as the previous experiments participated in the study. All completed the naming task. Half completed a recognition memory task and the other half received recognition exclusion instructions.

Procedure. As for Experiment 5, all participants initially learnt an auditorily presented study list, and then participated in the speeded naming task which was described as being designed to fill the delay before testing memory. After a delay of approximately 10 minutes (comparable with duration of the perceptual identification task in Experiment 5), participants completed the recognition and recognition exclusion task.

The naming task was run on an industry standard computer using

DMASTR software. Latency was measured using a voice switch and microphone. Participants were told that they would see strings of letters presented in the middle of the screen. They were to read, out loud, as quickly as possible, those that were presented in diamond brackets. All other procedural details were the same as for Experiment 5, with the words 'naming task' replacing 'word decision task' in the recognition and exclusion instructions.

163 Results

Naming. Average naming latencies for each repetition condition are shown in Figure 5. Only two errors (both for low frequency words) were recorded over all participants, so error data has not been included.

The overall effects of lexical status [F(1,25)= 203.52 , p <00.5], number of presentations [F(1 ,25)= 13.576], and number of responses

[F(1 ,25)= 40.41 0] were all significant . No significant main effect for frequency was found in the latency data [F(1,25)=2.082] but the interaction between frequency and number of responses was significant [F(1 ,25) =

10.707] with low frequency words eventually having shorter naming latencies than high frequency words in the 2P2R condition.

850

800 .' A·. • •. • •• •. • • ••• • • ••••••• •. •. • • •A, • • • • • • ··. ··. 750 ··...... 100 I1;- ~------~,,, c ...... - .. - Low Frequency ~ ...... ··•··Nonwords ,5"' 650 ...... z~

600

550.

500 ·1------.------~------. New Simple Repetition Response Repetition Repotltlon condltlon

Figure 5: Experiment 6: Naming latencies for high frequency words, low frequency words and nonwords. P = number of presentations of the stimulus word, R =number of responses required.

164 Comparisons of the repetition effects for each item type revealed no

significant effects of simple repetition [1 P1 R vs 2P1 R all Fs < 3.0]. Low

frequency words and nonwords showed priming when a response had been

made to the previous presentation [2P1 R vs 2P2R; F(1 ,25) = 98.9; F(1 ,25) =

20.57 for nonwords and low frequency words respectively] but no such

priming occurred for high frequency words [all Fs <1.63)

Recognition. The recognition and recognition exclusion data are

presented in Table 11. As for Experiment 5, all measures of memory are

based upon item analyses.

The recognition results for Experiment 6 are generally similar to those

from Experiment 5. Participants recognised items with above chance

accuracy [critical items vs new F(1,381) = 162.38], and there was no

difference between false positive rates for the different classes of items

(F<1.6). Words were more likely to be recognised than nonwords [F(1,381) =

10.23] and items that had been previously named were better recognised

than those which had not [F(1, 12)=1 06.67]. However, given that a response

had been required, number of previous responses made no overall difference

to recognition accuracy [F<1]. In Experiment 5, a general superiority of low

frequency words in most conditions was offset by the interaction between

frequency and number of responses, with the low frequency advantage

reversed by a high frequency superiority emerging only in the 2P2R condition.

This interaction is also significant in Experiment 6 [F(1 ,381 = 5.69], with high frequency words again superior only after two responses.

165 The results from Experiment 6 differed in three respects from those obtained in Experiment 5.

Firstly, number of presentations alone did not yield a significant main effect in Experiment 6 [F (1 ,381) = 3.65, ns].

Secondly, in Experiment 5, lexical status interacted with whether or not a response had been made in the decision task, with nonwords showing greater benefit from a initial classification decision. This interaction did not approach significance in Experiment 6 [F(1 ,381)= 2.44, ns].

Finally, a significant low frequency superiority was observed following the naming task [F(1 ,381) = 5.69], whereas no general frequency effect was found in Experiment 5.

Recognition Exclusion. The results for the recognition exclusion condition are presented in Table 11. In general, participants apparently understood and were able to perform the exclusion task, endorsing items from the auditory study list (38.5% selection) more often than both those from the naming task (20%) [F(1,381) = 299.69] and new items (22.5%)

[F(1,381)=216.77]. As in experiment 5, the false positive endorsement of critical and new items did not differ [F<1]. Furthermore, there were no significant differences among the critical items: none of lexical status, frequency, repeated presentation or repeated response had a significant effect on intrusion rates [all Fs < 1].

Word frequency interacted significantly with number of presentations of the stimulus [F(1 ,381)= 4.36]. False alarm rates for high frequency words were lower when the item was presented twice, whereas the opposite was

166 true for low frequency words. No other interactions were obtained [All F's < 1].

167 Table 11 Experiment 6. Percentage of critical items recalled from each presentation condition in the recognition and exclusion recognition tasks.

Repetition Condition

1POR 2POR 1P1R 2P1R 2P2R

High Recognition 25.40 27.50 52.92 50.84 68.33 Frequency Exclusion 23.22 16.43 24.29 12.5 13.93

Low Recognition 35.82 29.58 66.24 77.09 63.33 Frequency Exclusion 22.15 16.43 10.45 21.26 25.01

Nonwords Recognition 28.33 23.54 50.84 51.04 49.79

Exclusion 23.40 21.97 17.32 20.98 19.56

169 Table 12. Experiment 6: Process Estimates (Jacoby, 1991). Contribution of recollection and familiarity- based processes to the probability of retrieval of items in each condition. P= number of presentations. R = number of responses

Repetition Condition

1POR 2POR 1P1R 2P1R 2P2R

High Frequency Recollection 0.022 0.111 0.286 0.383 0.544

Familiarity 0.207 0.178 0.298 0.209 0.262**

Low Frequency Recollection 0.137 0.086 0.557 0.558 0.383

Familiarity 0.246 0.213 0.221 0.569 0.462

Nonwords Recollection 0.049 0.016 0.335 0.156 0.302

Familiarity 0.236 0.216 0.240* 0.216 0.271

* One item and ** Two items excluded. See footnote, p.144

170 Recollection: Table 12 presents estimates of the conscious contribution to performance calculated in the same manner as for Experiment

5.

Previous naming of items contributed significantly to their recollectability [F(1,381)= 65.12]. The estimate of the recollective contribution to memory for words was higher than for nonwords [F(1, 381)=7.39]. No significant overall effect of word frequency was found, although, as in

Experiment 5, frequency interacted significantly with the number of previous responses [F(1,381) = 6.52] because recollection for high, but not low frequency words was better for items that had been named twice.

Main effects for number of presentations and 1 vs 2 responses, and the interaction between lexicality and number of responses made- all significant in Experiment 5- were not replicated with the naming task.

Familiarity. Changing the study task from lexical decision

(Experiment 5) to naming (Experiment 6) eliminated the influence of lexicality on familiarity. However, a significant frequency effect was obtained

[F(1,378)=10.25). Number of presentations [F(1,378) = 4.31] and whether a response had been required [F(1.378) = 13.19] enhanced the contribution of familiarity to retrieval. Low frequency but not high frequency words gained familiarity as a result of increasing number of presentations [F(1,378)= 9.52]

171 Discussion

Experiment 6 confirms that the naming latency and lexical decision

tasks differ in terms of overall response latency and in terms of specific

interactions with priming conditions, but that the overall pattern of priming

produced by the two task is similar (Brown & Carr, 1993). The most notable

difference between the two results is that the shift from lexical decision to

word naming as the study task eliminated any within-task effect arising from

repetition alone, suggesting that these effects reflect processes specific to the

lexical classification task. The effects of repeated responding were still

evident both within the naming task and in subsequent memory retrieval.

The pattern of effects obtained for the memory tasks in Experiment 5

was replicated in Experiment 6. Nonword priming only occurred if a response

had been required to the nonword during the study task. Repetition alone

facilitated recognition of low but not high frequency words. Repeated

responding improved recognition of high frequency words only, even though

no latency priming was found for this manipulation in the naming task.

Therefore although some aspects of the pattern of priming arising within the

initial task appear to be task-specific, manipulations of repetition conditions

produce consistent effects on subsequent memory performance.

The effects of word frequency on the process estimates are less

clear-cut. An important, replicated finding from Experiments 5 and 6 was the reversal of the 'expected' low frequency advantage in recognition memory when two responses were made in the study task, and a mirror effect for high frequency words in this condition. The process estimates suggest that this

172 increase in recognition of high frequency words following two presentations is largely 'driven' by a gain in estimated recollection for high frequency words, and a decline in recollectability for low frequency words between 1 and 2 responses.

These conclusions complement those from a similarly motivated study by Guttentag & Carroll (1997) who used process dissociation procedures to investigate the recollection- and familiarity-based components of the word frequency effect. Without the response manipulation of present studies, they obtained evidence that the standard low frequency recognition advantage is largely recollective in origin.

While the present experiments 5 and 6 also suggest that recollective components contribute to the word frequency effect, they indicate that the relative contribution of these two components interacts with response and processing demands, such that the contribution of recollection and familiarity to frequency effects in recognition depends upon the extent and the nature of the participant's prior experience with the item.

In this sense, Experiments 5 and 6 suggest that the answer to

Guttentag and Carroll's (1997) question: "Is the low frequency word advantage a familiarity-based or recollection- based phenomenon?" (1997, p503) is that it depends upon the nature of the study task. In the passive, response free study conditions of items presented only once at study (1 POR), the present results are consistent with those of Guttentag and Carroll (1997) in suggesting that any superiority of low frequency words in recognition is largely attributable to the greater recollectability of low frequency words.

173 However, at the other extreme, following two classification or naming responses, the low frequency advantage is supplanted by a high frequency advantage, which appears to be the result of alteration to both the familiarity and recollection estimates.

Changing from lexical decision to naming also eliminated the influence of lexicality on item familiarity, suggesting that the effect of lexicality on the familiarity estimates of Experiment 5 also arose from processes specific to the lexical decision task in that experiment. In the naming task, lexicality appears to impact upon recollectability but not familiarity.

5. 3 Conclusions from Experiments 3 to 6.

Experiments 5 and 6 directly evaluated the relevance of factors influencing repetition priming to longer term direct and indirect memory processes. Experiments 5 and 6 also allowed assessment of the impact of frequency, lexicality and repetition type on familiarity and recollective processes as estimated using process dissociation procedures.

While each of Experiments 3-6 found evidence of repetition effects for high frequency words, low frequency words and nonwords, Experiments 5 and 6 suggested that the effects are responsive to different aspects of repetition, comprise different combinations of familiarity-based and recollective processes, and show differential transfer to subsequent memory tasks. The within and between task effects for repetition, frequency and lexicality are outlined below.

The design of the lexical decision and naming tasks allow priming arising from simple repetition of the stimulus to be assessed independently of

174 effects due to repetition of an appropriate response. The mechanisms implicated by each of these effects of repetition will be discussed separately.

Simple repetition.

In the lexical decision task, responses to words were facilitated for repeated items that had not required classification on their first presentation.

No such priming was evident in reaction time for nonwords, although the error data for Experiment 4 showed a transient inhibitory priming effect for nonwords following simple repetition. This effect was not replicated in

Experiment 5 where two items intervened between initial and subsequent presentation of the repeated nonword. None of these effects was significant in the naming task of Experiment 6.

Thus, both words and nonwords may show a short-acting priming effect due to an immediate repetition of an item in the lexical decision task.

While this effect does not influence nonword lexical decision time, it apparently results in greater confusability of nonwords with words, and therefore increased nonword errors.

Differential Word and Nonword repetition effects.

This effect of simple repetition common to both words and legal nonwords is resistant to surface (case) changes at the time of repetition, but does not survive a temporal lag and/or intervening items. The present results suggest that a single presentation of a nonword is sufficient to establish a form of representation which makes the item more likely to be confused with a word. As this representation has been shown to survive structural changes it

175 appears more characteristic of abstract, modification-based processes than phenomenal or instance-based episodic acquisition.

The structural regularity of the nonwords in the present series of experiments is important in this context. Rugg (1987; Rugg & Nagy, 1987) has investigated differences between the processes underlying repetition effects for words and nonwords using electrophysiological procedures. Rugg

(1987) reported that the ERP waveforms elicited by repeated legal nonwords were characterised by a late positive shift that was similar to that observed for repeated words, but of smaller magnitude and slower rise time. Rugg and

Nagy (1987) applied the same paradigm to investigate differences between legal and illegal nonwords and demonstrated that the late positive shift occurred for legal, but not illegal nonwords.

Although the Rugg (1987) and Rugg & Nagy (1987) procedures are technically quite different from those of Experiments 3-6, the implications of their findings parallel those from Experiment 3. In the Rugg studies, logistical requirements of ERP recording meant that participants were not required to respond to either the prime or the target but simply to count the number of words (Rugg & Nagy, 1987, Experiment 1) or nonwords (Rugg, 1987) presented in a mixed list of words and nonwords.

Clearly words and nonwords cannot be counted unless a lexical classification is made. As the repeated item was presented immediately after its first presentation and the dependent measure taken at the time of the second presentation, the task corresponds to the 2P1 R lexical decision condition of the present Experiment 4.

176 Rugg & Nagy argued that the similarity of the ERP waveforms elicited

by repetition of words and legal nonwords, and the differences between those

for legal and illegal nonwords, supported the claim that repetition effects for

legal nonwords reflect activation in a form of lexical memory rather than newly

acquired episodic representations. However, because legal nonwords are

not, in fact, represented in lexical memory, the activation they elicit is

incomplete and weaker than that for words. Drawing upon investigations of

repetition effects for non-verbal stimuli such as pictures, Rugg and Doyle

(1994) argue that repetition effects in ERP waveforms can be elicited by

stimuli for which there is no pre-existing lexical or semantic representation,

provided those stimuli satisfy stored criteria for possible, if not actual semantic

status (e.g. orthographical regularity of written stimuli, structural possibility of

pictures) The absence of ERP repetition effects for illegal nonwords and

abstract visual patterns implies that they are evoked only by the repetition of

stimuli possessing attributes that lead to the generation of "one or more

unitized codes" (p. 129).

The finding from Experiment 4 of transient inhibitory effects of

repetition for immediately repeated nonwords seems to support this claim.

Immediate repetition of legal nonwords yielded a repetition effect which is

manifest as increased confusability with words and is resistant to surface

structural changes. Familiar nonwords thus appear to have gained partial

access to an abstract representational system. Insofar as this system is specific to word and wordlike stimuli (Rugg & Nagy, 1987), it is probably best described as "lexical" rather than "episodic": In terms of the distinctions

177 outlined in Chapter 1, legal nonwords appear to be sensitive to some form of modification based priming mechanism.

One account of the inhibitory effects of simple repetition on nonword lexical decision errors might be that the nonwords themselves are not producing 'lexical' activation. Rather, the effect might be attributed to activation of existing sublexical representational structures, common to both words and the present sample of nonwords (e.g. Dorfman, 1994). However, such an interpretation provides no explanation of the interaction between simple repetition and lexical status that was observed in Experiment 4. Error rates were low to the first presentation of the nonword, but increased when it was repeated immediately. Thus, recently presented nonwords are confused with words while new nonwords are not. If nonword priming effects simply reflected sublexical activation, there would be no reason to expect a differential impact of the first and second presentation of the nonword.

Moreover, since the perceptual format of the first and second presentation of the nonword were different, the delayed classification cannot be due to activation of purely perceptual features. Thus, the inhibitory effect of simple repetition on nonword classification appears to indicate that some abstract unitized representation of the whole item is acquired from a single exposure to a nonword (Rugg & Doyle, 1994), and yields a bias to classify the stimulus as a word.

The fact that such an effect was not evident when nonword presentations were separated by a longer lag and intervening items

(Experiment 5) suggests that the unitized representation that is apparently

178 established on the basis of simple presentation of a nonword either decays rapidly or suffers catastrophic interference.

By contrast with the above inhibitory effect of simple repetition of nonwords, classification of nonwords on their initial presentation does influence performance when the stimulus is repeated later in the item sequence.

Thus, the effects of simple repetition of a stimulus appear to reflect modification of some form of abstract representation of the item. Since such representations do not appear to be developed for illegal nonwords (Rugg &

Nagy, 1987) they seem to reflect lexical knowledge rather than being purely episodic. This implies that legal nonwords are rapidly unitized to form an abstract representation of the stimulus pattern. However, this representation suffers interference from successive items. The present results therefore imply that simple presentation of an item, without any requirement for elaborative processing, can yield repetition effacts, at least in tests of indirect memory, that appear to depend on some form of abstract lexical representation.

Response repetition.

In contrast with simple repetition, repetition of a stimulus that was responded to on its first presentation produced robust within- task priming for both words and nonwords. It thus appears that this manipulation leads to either the acquisition of a novel representation of the stimulus, or an association between an existing representation of the stimulus and its task-

179 appropriate response. The fact that these repetition effects are at least as strong for nonwords as for words indicates that they do not depend on a pre­ existing representation, and that, unlike the representations acquired through simple repetition, responding to a nonword yields a durable trace that survives the presentation of intervening items. Indeed, the results of the memory tasks (Experiments 5 and 6) indicate that the representations of both words and nonwords established in the study task are consciously available for subsequent recall after a delay of at least 20 minutes. By placing primary emphasis on the role of task-specific practice in the development of a form of generalisation of the stimuli the above account is similar to that provided by

Logan (1988) of automaticity (see Chapter 1, p.36)

5. 4 Repetition effects in memory.

The six experiments here employed a variety of methodologies to investigate the relationship between familiarity-based memory processes and repetition. There were two major reasons for investigating the effects of study-task repetition on subsequent recognition memory performance. First, evaluating the transfer of repetition effects to a later task with different response requirements provides insight into the durability and generality of the representational changes presumed to underlie the repetition effects observed within the study tasks. Experiments 1 and 2 suggested precisely this- effects of repetition which could be observed within a study task

(Experiment 1, study and test interleaved) were preserved when the memory task was delayed for up to ten minutes (Experiment 2) in a delayed test task.

Second, comparison of the effects of repetition on performance in

180 recognition and exclusion tasks provides evidence about the nature and conscious accessibility at the time of test of the memory traces created by stimulus repetition. Recognition memory was sensitive to study-task repetition. Both words and nonwords that had been responded to in the study task were more accurately recognised than new items or items that had been presented without a response requirement. This indicates that responding to an item has an effect on memory that is sufficiently durable to influence perfor.mance across at least a 20 minute delay, and sufficiently general to influence a completely different task.

By contrast, the effect of repeated presentation of the item alone was both task and item-specific being evident only for low frequency words, and only under lexical decision study conditions (Experiment 5). The impact of repeated responses to an item was also item-specific leading to better memory only for high frequency words. However, this memory advantage was evident following both lexical decision and naming tasks (Experiments

5,6). This combination of effects of repetition on memory suggests the involvement of a number of different mechanisms.

The robust memory advantage for both words and nonwords that were responded to in the study task suggests a durable priming mechanism that does not depend on pre-experimental experience with the item. The generality of this effect across words and nonwords is consistent with acquisition accounts which assume that repetition effects reflect the direct consequences of recent exposure to the items rather than activation of pre­ existing representations. Consistent with the phenomenal episodic account,

181 false positive rates in the exclusion task did not differ as a function of prior

response requirements.

This conclusion must be modified somewhat by the interactions with

responding observed in Experiments 5 and 6, and by the process estimates

derived from each task. The influence of responding on recollection, while

significant as a main effect, emerges from complex interactions with lexicality

and frequency.

The contribution of recollective memory to recall for nonwords

increased as a function of number of responses, as outlined above.

However, the theoretically independent contribution of familiarity to nonword

recall declined (Experiment 5) or was unchanged (Experiment 6) in response

to the same manipulation. Similarly, the impact of response repetition was

not consistent across word ·frequency. In both Experiments 5 and 6, a

"typical" low frequency advantage was observed in four of the 5 repetition

conditions and this was largely reflected in the recollective component of

retrieval. However, in both experiments, this advantage was eliminated when

two responses had been made in the study task. This reversal of the low

frequency advantage was again largely driven by a marked increase in the

recollective component of retrieval for high frequency words and a marked

decline in 'recollection' for low frequency words. In Experiment 5, a

significant mirror effect was also obtained, with high frequency words more

likely to be recognised and producing fewer false positives than low frequency words. This is the reverse of the typical mirror effect, which usually

accompanies the recognition advantage for low frequency words (Glanzer &

182 Adams 1985, 1990). The more typical finding and was obtained as a result of multiple presentations of the stimulus in Experiment 5.

A final general finding common to experiments 5 and 6 concerns the influence of stimulus attributes upon the derived estimates of familiarity and recollection. In Experiment 6, the process estimates appear to have dissociated the effects of lexicality and word frequency, with lexicality but not frequency influencing recollection overall, and frequency but not lexicality influencing familiarity.

In very broad terms, differences between repetition effects for words and nonwords and for high and low frequency words tend to implicate modification-based mechanisms because they imply that repetition effects depend upon the pre-experimental history of the item. However, is it clear from the above that it is unlikely that any single account will be found which can parsimoniously explain each of the above results.

183 Chapter 6: General Discussion

6. 1 Familiarity and perceptual fluency.

In broad terms, the research reported in this thesis suggests that although high frequency and low frequency words and nonwords all benefit from repetition, repetition priming effects have different origins for different item classes.

Repetition. frequency and familiarity

Differential effects of repetition on words and nonwords have often been attributed to a familiarity-based mechanism. ..Familiarity" has been defined as a sense of ease of processing of the item, arising from previous processing experiences. Items become familiar as a consequence of both pre-and intra-experimental frequency and thus, at the time of the memory test, all old items are familiar, with the extent of their familiarity depending upon baseline frequency and the number of intra-experimental presentations.

More familiar items are processed more efficiently on subsequent encounters because of the 'perceptual fluency' accrued through previous experience

(Jacoby, 1988).

Baseline and intra-experimental familiarity

The notion of perceptual fluency has been used to explain differences between both the effects of repetition and the differential accuracy of recognition memory for high and low frequency words. Mandler (1980) argued that the memory advantage typically observed for low frequency 184 words in recognition memory tasks (e.g., Gregg, 1976) occurs because the change in the perceptual fluency associated with an item as a function of recent exposure is larger for items with lower "baseline familiarity". Thus the relative perceptual fluency gained from a single stimulus presentation is greater for low frequency words and provides the basis for familiarity-based recognition judgements.

Differential perceptual fluency has also been argued to account for the enhanced repetition effect often observed for low as compared to high frequency words (e.g., Scarborough et al., 1977). Rugg and Doyle (1994) present findings that a late P300-like ERP component is enhanced for low frequency repeated words in both indirect (Rugg, 1990) and direct (Rugg &

Doyle, 1992) memory tests. As this component appears uniquely sensitive to the extent to which lexical processing is performed upon the stimulus, they argue that it is unlikely to be the result of nonspecific episode-based learning

(Rugg, 1990). They suggest that the later P300-like component confirms the contribution of a process sensitive to the relative familiarity of the evoking item to performance in both paradigms, with the relatively unfamiliar low frequency words receiving more processing at the time of presentation.

The findings for low frequency words in Experiments 5 and 6 are consistent with this notion of familiarity. In addition to the larger repetition effects observed for low frequency words under the indirect memory test conditions of the lexical decision and naming tasks, recognition memory tended to be more accurate for low frequency words than for high frequency words or nonwords, with the exception of the 2P2R conditions. Further, the

185 fact that the repetition effects for low frequency words differed from those

observed for both nonwords and high frequency words implicates a

mechanism like relative perceptual fluency that is sensitive to the both the

baseline activation level of an abstract representation and familiarity accrued

through intra-experimental experience.

The level of baseline familiarity alone cannot explain why low

frequency words should be advantaged relative to high frequency words; an

index of the change in familiarity associated with exposure to the stimulus

within the experimental session seems necessary. However, while a

mechanism that is sensitive only to incremental familiarity acquired during the

experiment can explain the observed effects for frequency, it would also

predict a greater increment in familiarity for nonwords than words, which was

not evident in the familiarity estimates derived from Experiments 5 and 6.

Indeed, while memory for nonwords improved as a function of response

repetition in Experiments 5 and 6, this was consistently due to gains in the

recollection rather than the 'familiarity' component of recognition.

6. 2 The Process Dissociation operationalisation of familiarity.

The present results therefore demand further specification of the

relationship between perceptual fluency, baseline and intra-experimental familiarity and the estimates derived from the process dissociation procedure.

Jacoby (e.g .1991 , Jacoby & Dallas, 1981) identifies familiarity with perceptual fluency. However, as reviewed in Chapter 4, familiarity has also been identified with such terms as 'unconscious memory' and 'automatic processing'. Assuming both baseline and intra-experimental familiarity are

186 important to retrieval, which, if either, is best represented by the A term of the process estimation procedure?

Although Jacoby and others identify 'familiarity' with a number of conceptual psychological processes, the empirical procedure used in process dissociation studies is effectively a source monitoring task. Participants are required, at the time of exclusion testing, to reject items that they are able to attribute to a specified, usually within-session, source. Intrusions into the exclusion task reflect, at a phenomenological level, a lack of awareness of the source of the most recent change in perceptual fluency. In terms of the above discussion, they are not being required to monitor the magnitude of the change in fluency itself, but rather to identify the specific occasion of an increase in fluency. The process estimation procedure can thus conflate source availability with sensitivity to relative perceptual fluency.

This conflation is conceptually acceptable if one accepts a radically

'episodic' view in which instances of learning are not distinguished from the material learned. However, in attempting to specify the properties of baseline familiarity and intra-experimental familiarity processes, these conflated notions of familiarity need to be distinguished.

Process dissociation and nonword familiarity

By definition, low frequency words have low but not zero baseline familiarity, high frequency words have high baseline familiarity, and nonwords have close to zero baseline familiarity, allowing for possible sublexical components. As outlined above, a mechanism based upon the relative change in fluency associated with intra-experimental presentation would

187 account for the greater benefit to low frequency words arising from a number of repetition conditions. However, this trace interacts with the representation of the actual baseline level of fluency. In the case of nonwords, the first presentation within the study task does not change the relative fluency of the items, it initialises it.

At the time of retrieval, the process dissociation procedure separates information for which the source is known from that for which it is not known

(Following Mulligan & Hirshman (1997) these two classes of information are referred to as diagnostic and nondiagnostic respectively). The subtraction of exclusion from recognition in the calculation of the recollection term leaves only the diagnostic component. In the exclusion conditions of the present experiments, participants are effectively instructed to distinguish between nonwords presented once in the auditory task from those presented and possibly repeated in the visual lexical decision and naming tasks. The forced choice recognition or exclusion tasks are then also presented visually. The only previous encounter with these nonwords in the test modality is therefore during the previous study tasks. Therefore wherever the written form of a nonword seems familiar, it might be presumed to be an item that was presented in the study task. This is not the case for words, which will have been encountered in both modalities on many pre-experimental occasions. In this sense, even if the participant does not have an explicit recollection of the nonword having been encountered previously, they may presumptively attribute any increase of familiarity to prior encounters in the decision and naming tasks. As nonwords become more familiar they may therefore

188 become easier to exclude. Successful exclusion of old items is always represented in the process estimates as evidence of recollective, rather than fluency based processes. Therefore, if perceptual fluency can be used as information about the source of familiarity of a nonword, it will be represented in the R term following process dissociation procedures. An experience of nondiagnostic familiarity, phenomenologically equivalent to that experienced for words, may come to be represented in the 'recollection' estimates for nonwords following process dissociation.

Repetition then impacts differentially on the processes contributing to word and nonword priming. For nonwords, fluency can be used as evidence regarding the source of the previous encounter. As the first encounter with the item takes place within the experimental session, subsequent repetition, merely increases the extent to which a sense of familiarity can be specified to the present circumstances.

Thus while an increase in familiarity or fluency of nonword processing as a function of repetition within the study tasks may be represented in the process estimates as an increasing R term, this conclusion is a consequence of the identification of source information with 'recollection' accompanied by the strong assumption of independence made by the original processes estimation procedures (Jacoby, 1991) that were applied in Experiments 5 and

6. As discussed in Chapter 4, there are a number of alternative assumptions about the relationship between recollection and familiarity. The redundancy variant of the model (Joordens and Merikle, 1993, see Chapter 4) does not contain the same strong presumption of the independence of familiarity and

189 recollection- indeed it- presumes that recollection is always accompanied by familiarity, rather than independent of it. Thus, while this model will still represent diagnostic perceptual fluency in the R term, it will also be represented in the A estimate, thereby reducing the relative impact of the source information.

The Redundancy model

To demonstrate the implications of these different assumptions, Table

17 presents the estimates of the familiarity term for Experiment 5 as calculated by the original (independence) model and the redundancy models.

The redundancy model uses the same equation as the independence model for the calculation of the R term so that term is the same in both models. As the redundancy model also assumes that recognition is always accompanied by unconscious processes, the proportion of items recalled in the recognition task becomes the familiarity term of the redundancy model.

190 Table 17. Experiment 5. Comparison of familiarity estimates derived under the independence (Jacoby, 1990) and redundancy models (Joordens & Merikle, 1993)

Model 1POR 2POR 1P1R 2P1R 2P2R

High Independence 0.322 0.290 0.433 0.311 0.456 Frequency Redundancy 0.433 0.304 0.583 0.611 0.732

Low Independence 0.151 0.280 0.331 0.407 0.468 Frequency Redundancy 0.244 0.428 0.683 0.722 0.705

Nonwords Independence 0.230 0.225 0.271 0.302 0.240

Redundancy 0.286 0.269 0.430 0.427 0.469

191 The familiarity estimates derived according to the redundancy model are higher than those from the independence model for all conditions because the redundancy model does not remove the shared contribution of conscious and unconscious processes. Whenever recognition exclusion performance is above zero, the redundancy model will yield a larger estimate of the A value than the independence model.

A second direct outcome of the estimation procedure is that the redundancy model will never return an A estimate lower than the R estimate for the same condition, whereas the independence model can do so.

Of more theoretical significance is the pattern of differences between the estimates derived from the two estimation procedures. As Joordens and

Merikle (1993) note, there is no overwhelming theoretical or empirical reason to choose the redundancy model over the independence model, and the decision must be based on consideration of completeness and parsimony.

Compared with the independence model, the redundancy model suggests a more monotonic increase in familiarity for high frequency words and nonwords as a function of repetition when a response has been made (all conditions from 1P1 R to 2P2R), while the increase from 2P1 R to 2P2R for low frequency words is absent from the redundancy model estimates.

To clarify this difference, the familiarity estimates shown in Table 13 were converted to gain scores reflecting the difference between those conditions in which the participant had the most and the least intra­ experimental experience with the items (2P2R and 1 POR respectively), expressed as a ratio of the 2P2R estimate. Under the independence model,

192 high and low frequency words show 29 and 67 percent gains in familiarity respectively across the repetition conditions, while nonwords show only a 4 percent gain. In contrast, under the redundancy model, the high frequency words show a 41 percent gain, low frequency words are unchanged, and nonwords show a 39 percent gain from the left to the right of the table. That is, the redundancy model yields larger estimates of the change in familiarity for high frequency words and nonwords with repetition than does the independence model.

This difference between the familiarity estimates derived from redundancy and independence models is relevant to the earlier discussion of differences between the role of source knowledge in word and nonword decisions. Since the redundancy model emphasises the shared, rather than the independent contributions of familiarity and recollective components to recognition, the model would interpret above findings as suggesting that responding to nonwords does result in an increase in familiarity, but it is the component of familiarity which contributes to recognition, rather than being independent of it. This is not intended as evidence for either model over the other, but the contrast exposes the implications of the assumptions implicit in the independence model.

193 6. 3 Study Task Differences

There are some indications that the basis of the repetition effects on memory for low frequency words are somewhat dependent on the nature of the study task. In Experiment 6, where the initial exposure(s) occurred in a word naming task, overall recognition hit rate was higher for low than high frequency words, but low frequency words did not show a significantly greater benefit from additional presentations or responses, and frequency had no significant effect on false positive rate in the exclusion task. In contrast, when the initial exposure occurred within a lexical decision task, frequency did not significantly affect overall recognition hit rate, but low frequency words showed a significant increase in accuracy due to a second unclassified presentation that did not occur for the other item classes. Further, low frequency words yielded lower false positive rates in the exclusion task.

If these effects are attributed to relative perceptual fluency, they imply that word naming leads to a greater overall increase in intra-experimental familiarity, and therefore a greater increment in relative perceptual fluency, than lexical classification. Alternatively, it might be argued that lexical classification of high frequency words is, at least sometimes, based on their high level of baseline familiarity (Balota & Chumbley, 1984, although see

Kinoshita, 1989 for evidence inconsistent with this account) without the explicit retrieval and evaluation required for low frequency words. By this account, the absence of an overall difference in hit rate following the lexical decision task between high and low frequency words reflects the contribution of baseline familiarity to recognition memory judgements for high frequency

194 words. These familiarity-based responses obscure the recollection-based advantage in memory for low frequency words. Consistent with this view, the exclusion data for Experiment 5 indicate that recognition judgements for high frequency words are less dependent on explicit recollection of the encoding experience than is the case for low frequency words.

Thus the recognition memory data for low frequency words appear to implicate a mechanism sensitive to relative perceptual fluency (Jacoby &

Dallas, 1981; Rugg & Doyle, 1994) but the high false positive rate for high frequency words previously presented in a lexical decision task suggest an independent contribution from the baseline familiarity of abstract lexical representations. Experiment 6 further suggests that, in contrast with the lexical decision task, the naming task enhances the availability of a conscious episodic trace for high frequency words. Further comparisons of the memorial consequences of different initial processing tasks are necessary to evaluate these implications of these differences both for understanding the mechanisms underlying repetition priming and for further specifying the processes involved in lexical retrieval.

6. 4 Contextual specification.

There is a further interaction between word frequency and repetition that seems to implicate another contribution to the repetition effects in direct memory performance. This is the finding, significant in both the hit rate data and recollection estimates for both Experiments 5 and 6, that high frequency words were better remembered when they had been responded to twice rather than once in the study task. No such improvement in memory occurred

195 for low frequency words or nonwords and, indeed, low frequency words showed the opposite effect in Experiment 6, especially in the estimated recollection data. The exclusion data for Experiment 5 showed a small but significant decrease in the false positive rate for high frequency words in the

2P2R condition confirming that the enhanced memory for multiply responded high frequency words reflects a consciously recollectable trace rather than familiarity-based processes.

Thus, memory for high frequency words benefits from a second response during the study phase. No such benefit accrued from re­ presentation without a response requirement, so the memory advantage appears to be due to the more elaborative processing required to select an appropriate response. Such an influence seems to imply an episode-specific representation that is available to conscious recollection. However, since no equivalent memory improvement occurred for nonwords or low frequency words, it does not appear to be attributable to either episodic or abstract representations alone.

Further, the memory advantage due to repeated responses to high frequency words appears to reflect mechanisms specific to recognition memory because high frequency words did not show an equivalent enhancement of the repetition effect for these items in the lexical decision or naming task. All classes of item showed an additional repetition effect when responded to a second time and, if anything, the effect was least evident for high frequency words. However, the outcome of this second response to high frequency words is an enhancement of the item's availability to conscious

196 recollection processes.

Intra-experimental familiarity and specification.

Explanation of the above aspect of the memory data seems to implicate an additional construct that will be referred to as "specification".

Specification refers to the extent to which an item is identified with a unique previous occurrence. Lexical classification and speeded naming provide task-specific cues regarding the subject's most recent experience with a given item. These experiences yield traces that support the "recollection-in-context" that permits transfer to a memory retrieval task. Classification and responding do not necessarily alter the representation of the item itself, but rather "tag" the item in a way that specifies its occurrence in the study task.

This specifying process yields a memory trace that provides a part of the support for what is referred to by Jacoby ( 1991) as 'recollection' or by Mandler

(1980) as 'remembering'.

Specification and word frequency

While specification refers to a particular processing episode, it operates on an existing representation. Thus for known words, specification is identified with a modification rather than an acquisition mechanism, and the processes underlying specification of existing representations are distinct from those involved in the acquisition of a new episodic representation that must occur for nonword stimuli.

There are two ways in which the distinction between familiarity and specification can be applied to the present data. The first is to assume that

197 repetition effects on recollection are always due to specification, and that

specification is acquired more quickly for low than high frequency words.

There are a number of possible reasons that specification might be reduced for high frequency words. It is argued that items gain specification as a result

of being strongly identified with the context in which they were encoded.

Thus, high frequency words, which are encountered across a number of contexts, may be poorly specified to any single context and may therefore have a low probability of being recalled under instructions specifying a particular context. In this sense, the high baseline familiarity of common words may interfere with the specification necessary for successful recollection. In other words, high levels of pre-experimental familiarity may actually impede recognition memory performance.

While this interpretation is compatible with the higher false positive rates observed for high frequency words in Experiment 5, it fails to explain why low frequency words do not show a benefit from multiple responses during study. The memory data for both experiments indicate that recognition relies principally on explicit recollection which, according to this interpretation, is identified with specified memory traces. So the further specification afforded by multiple response requirements should enhance the specification of the representations of all items for which there is an existing representation.

It might be possible to argue for some asymptotic effect of specification to explain the results of Experiment 6, where low frequency words do not improve with further responses. However, this cannot account

198 for the cross-over effect observed in Experiment 5 where memory for low frequency words was actually worse following two than one response, while memory for high frequency words improved.

The second possible explanation of the differential effects of multiple responses on high and low frequency words assumes that the memory advantage for low frequency words following a single responded presentation is due to relative perceptual fluency, while that for high frequency words responded to twice reflects a separate contribution due to specification. This account may also explain the high frequency mirror effect described for

Experiment 5, where response repetition improved recognition memory performance while simultaneously reducing false positive rates for high frequency words. The initial high familiarity and low specification of high frequency words is overcome by the enriched specification experience of multiple responding. Common words classified often within the experiment are therefore well recognised due to the combination of familiarity and specificity, but are also easily rejected due to their elevated specification to the encoding context. This is a very similar argument to that more commonly used for the low frequency mirror effect (See p.137), but it places slightly greater emphasis on the extent and nature of the intra-experimental experience with the item and the degree to which that experience gives rise to specification, rather than simply baseline and relative changes in familiarity.

6. 6 Electrophysiofogical support for specification

This claim that two different mechanisms contribute to repetition priming for words, and that both are sensitive to word frequency in somewhat

199 different ways, is supported by electrophysiological evidence. in addition to the effects of word frequency on late positive ERP components that were briefly mentioned earlier, both frequency and repetition also influence the earlier negative N400 component. N400 is also sensitive to manipulations of semantic and contextual priming. The complex of factors that influence N400 suggest that it reflects contextual integration processes (Rugg & Doyle, 1994;

Karayanidis, Andrews, Ward & McConaghy, 1991 ). Within this framework, the differential N400 observed for high and low frequency words is interpreted as indicating that "low frequency words are, in general, more difficult to integrate with the context of their presentation" (Rugg & Doyle, 1994, p. 139).

Previous investigations of the integration hypothesis have focused on manipulations of semantic and sentential context. Mitchell, Andrews & Ward

(1993) found that the enhanced N400 usually observed to incongruous sentence completions was reduced for repeated words, even when they were paired with different, but familiar, sentence contexts. The priming reflected in

N400 therefore appears to reflect both associative and episodic relationships.

To incorporate the present results for high frequency words it is necessary to extend the notion of episodic relationships to include those associated with the task requirements of lexical classification and word naming and assume that high frequency words are more easily integrated with these contextually specifying features.

Although the contextual integration hypothesis provides a plausible account of the complex of factors that influence N400, Rugg and Doyle point out that the process remains poorly defined. They also claim that there is, as

200 yet, no evidence that differences in N400 are associated with better

performance in direct memory tests as would be expected from the relationship between integration and memory. The present results might provide some insight into this failure. Integration is only one of the factors influencing memory accuracy. It provides one source of information that facilitates conscious recollection of a processing episode. But, according to the present interpretation, effects due to integration of an isolated word with the task context in which it occurred only influenced memory for high frequency words which were classified more than once. Recollection of other items relied on other consequences of repetition that do not depend on integration or specificity of representations. Detecting the relationship between integrative processes during encoding and subsequent memory therefore requires refined experimental and analysis procedures which allow separation of the various processes contributing to retrieval of a given item.

In addition to the influence of frequency and repetition on N400, Rugg and Doyle (1994) argue that there are independent effects of both of these factors on late positive ERP components. Although these components resemble P300, the effects of repetition do not appear to reflect factors such as stimulus probability or response confidence that are known to influence

P300. Rather the late positivity observed in repetition paradigms is sensitive to effects of frequency and repetition on ERPs elicited in both direct and indirect tests of memory. This component differentiates between old and new items, and the differentiation is more marked for low than high frequency words. Rugg and Doyle argued that these characteristics are compatible with

201 the view that the component reflects the ...

disparity between the intra- and extraexperimental familiarity of an item and that this disparity is computed online, as proposed by dual­ process models (1994, p. 144)

This view was subsequently modified by Doyle, Rugg & Wells (1996, also Rugg, Cox, Doyle & Wells, 1995), who suggested that the observed late positive ERP effects for familiar and unfamiliar items may reflect a difference in the nature of the representations of the items themselves, rather than a difference in the processing operations to which they were subjected during the experimental session.

However, insofar as the Evoked Potential literature suggests differential activation in response to items as a function of their familiarity, whether that difference is at the representation or processing level, the present results provide an important behavioural correlate to that literature.

Low frequency words yielded larger repetition effects in both the indirect memory tests provided by the study tasks, and in the direct test of recognition memory. Further, the higher overall false positive rate for high frequency words in the exclusion test of Experiment 5 suggest a direct effect of baseline familiarity and are therefore compatible with the claim that this information is available to allow computation of relative perceptual fluency. Finally, the different pattern of repetition effects observed for high and low frequency words both within and across tasks are consistent with the involvement of separate mechanisms that differentially impact on performance for the two frequency classes.

202 6. 7 Conclusions

The results from this series of experiments add to the evidence that a number of different mechanisms contribute to the effects of repetition. They provide more refined insight into the nature of these mechanisms than most previous behavioural investigations.

Experiments 1 and 2 suggested that, when a direct investigation of familiarity is used, repeated exposure increases familiarity without altering recognition memory performance, as predicted from a number of dual­ process models. Paradoxically, Experiments 1 and 2 also suggested that, following a single presentation, familiarity-based responding is inhibited relative to recognition. The finding of inhibition of weakly activated items was suggested to be consistent with the model of surround-on-centre inhibition suggested by Carr and Dagenbach (1990). It was argued that the weak

'activation' of items under such conditions may present a conflict between a form of familiarity arising within the task, and the familiarity associated with their being known words, and that this conflict may deter participants from making 'familiarity' judgement to old items in this case.

Experiment 2 also demonstrated that the effects of repetition had persisted over at least several minutes, and that some of these effects were evident in a procedurally distinct transfer task. This generated the suggestion that at least some components identified as contribution to 'repetition priming' may be general to a range of memory measures, and motivated the later studies.

Experiments 3 and 4 developed a continuous lexical decision

203 procedure that allows the effects of repeated presentation to be separated from those due to a previous response to the item. Experiment 4 obtained evidence for short-acting repetition priming of nonwords which had been the subject of a prior classification response. This priming was manifest as an increase in error rate for nonwords which had been classified in the immediately preceding trial. As this priming was insensitive to a change in case between the two presentations, it appears have more resemblance to abstract 'lexical' or sublexical processes than to the acquisition of new episode-specific knowledge.

Experiments 5 and 6 expanded the continuous study task in combination with the use of Jacoby's (1991) process dissociation procedures in order to disentangle effects due to familiarity from those reflecting conscious recollection. This permitted a fine-grained evaluation of the mechanisms underlying superior performance for repeated items. The comparison of repetition effects for words and nonwords, and for high and low frequency words enhances the diagnostic potential of the research by providing insight into the nature of the representations subserving repetition priming.

This analysis of the mechanisms underlying repetition effects suggest the parallel involvement of both abstract lexical representations and newly acquired episodic traces, as well as an episode-specific modification process referred to here as 'specification'.

Differences between repetition effects for high and low frequency words are compatible with previous evidence of a process sensitive to relative

204 perceptual fluency and also implicate an integrative process that yields a contextually specified memory trace which is accessible to later conscious recollection. In the case of nonwords, it is suggested that the context of their initial presentation establishes, rather than modifies their perceptual fluency, and as such both recollective and fluency-based processes can be represented by the R term derived by process estimation procedures.

The experiments thus disentangle the mechanisms contributing the effects of repetition both within a single 'repetition priming' task and following transfer to a subsequent memory test. They also suggest that the 'familiarity' term from the process estimation procedure may systematically underestimate the influence of relative perceptual fluency on recognition under conditions where the item is initially presented within the process dissociation paradigm.

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222 Appendices

223 Appendix A. Stimulus lists: Experiments 1 and 2

List A List B List A List B 1 DEGREE INCOME 31 LOSS KING 2 TEST FAST 32 BILL REST 3 COMMAND CAPITAL 33 PIECE DANCE 4 BOTTLE LEADER 34 MEMBER RECORD 5 BANK HILL 35 BOOK FELL 6 CHIEF ISSUE 36 CAMP TEAM 7 POOL CENT 37 COVER SPOKE 8 STORE CLEAN 38 DUST STAY 9 LORD CLUB 39 FALL COLD 10 CAPTAIN PRODUCE 40 FIGHT FACTOR 11 FOOT PASS 41 GLASS EARTH 12 CALL HOLD 42 WINE POET 13 TRAIN HEART 43 MAIN FINE 14 RISE FAIR 44 MARKET CATTLE 15 REPORT CLAIM 45 MURDER DOCTOR 16 HUSBAND DINNER 46 PATIENT COUNCIL 17 JUDGE GREEN 47 PLANE TITLE 18 ARMY FILE 48 RADIO SPACE 19 VOLUME VALLEY 49 RAIN MASS 20 DANGER COLUMN 50 SERIES SUMMER 21 GROWTH PERSON 51 SHIP LEAD 22 SURFACE JUSTICE 52 SIGHT QUIET 23 UNIT TRIP 53 SQUARE METHOD 24 ROLE WIDE 54 STAFF RANGE 25 HELL HOUR 55 STEP LADY 26 ANSWER LETTER 56 TEETH STORY 27 FOOD DEEP 57 WALK ROCK 28 CORNER WINTER 58 WINDOW POETRY 29 PERMIT LENGTH 59 WRONG REACH 30 ROUND RIVER 60 YOUTH PLANT

224 Appendix B. Raw data and principal analyses: Experiment 1.

Percent Endorsement of old items in recognition and familiarity tasks 14 MILLISECONDS 42 MILLISECONDS 1 5 10 1 5 10 Rec. Fam. Rec. Fam. Rec. Fam. Rec. Fam. Rec. Fam. Rec. Fam. 1 30 50 40 50 80 70 70 30 70 60 100 70 3 40 40 70 80 60 50 50 50 50 60 50 70 5 40 20 50 60 50 60 50 40 90 70 80 80 7 50 60 60 50 40 30 40 70 30 60 50 50 9 70 30 40 40 30 30 60 30 40 50 70 40 11 70 50 30 60 40 60 50 50 40 40 40 50 13 50 50 60 80 60 70 30 10 80 60 80 50 15 80 80 50 40 30 40 70 10 80 60 80 60 17 50 50 50 30 40 40 60 80 80 60 70 60 19 70 30 40 50 60 50 80 50 80 90 100 90 21 50 40 50 60 70 60 70 50 70 90 90 100 23 40 70 50 30 50 20 70 60 80 100 100 80 25 30 70 70 70 30 80 70 40 70 80 90 80 27 90 50 60 30 30 60 80 30 50 20 40 60 29 50 40 50 90 50 40 70 70 60 60 100 80 31 70 20 30 40 50 70 70 50 70 40 90 60 List B 2 50 60 60 40 40 50 50 50 70 70 80 100 4 20 40 70 40 60 30 70 50 40 70 70 60 6 60 50 30 30 40 30 50 30 50 30 60 40 8 40 20 70 60 60 70 60 60 70 70 90 90 10 50 80 60 90 50 50 50 70 30 60 40 50 12 20 30 40 30 30 50 80 80 80 100 100 100 14 50 50 90 70 60 30 70 80 80 100 100 100 16 40 30 40 30 70 30 70 70 10 70 40 70 18 50 60 60 40 60 50 90 80 90 80 100 100 20 50 50 50 60 70 80 90 90 90 90 100 100 22 40 50 60 40 60 40 80 80 50 90 80 90 24 60 20 50 70 40 70 100 90 80 70 100 100 26 50 40 40 40 50 50 70 70 50 80 70 80 28 60 30 40 60 60 30 50 50 60 40 70 50

225 Analysis of variance table: Experiment 1.

Source SumSQ df MSQ F

LIST 1026.910 1 1026.910 1.15 ERROR 24995.310 28 892.690

QUESTION 640.000 1 640.000 2.64 ERROR 6798.884 28 242.817

DURATION 26351.110 1 26351.110 35.46 ERROR 20805.430 28 743.051

1 VS.5 REPS 1083.750 1 1083.750 2.87 ERROR 10574.110 28 377.647

(1&5) vs 10 REP 3336.806 1 3336.806 12.46 ERROR 7496.875 28 267.746

QUEST. X DURAT. 27.778 1 27.778 0.12 ERROR 6632.813 28 236.886

QUEST X [1v5] 1450.417 1 1450.417 10.02 ERROR 4051.339 28 144.691

QUESTX [ ( 1&5) v10] 1.250 1 1.250 0.01 ERROR 6622.323 28 236.512

DURAT X [1v5] 3.750 1 3.750 0.02 ERROR 6933.481 28 247.624

DURAT X [1&5v10] 3166.806 1 3166.806 23.26 ERROR 3812.202 28 136.150

DUR.X QUESX[1v5] 1450.417 1 1450.417 10.02 ERROR 4051.339 28 144.691

DURxQUESx[1&5v10] 40.139 1 40.139 0.60 ERROR 1861.161 28 66.470 D

226 Appendix C. Experiment 2: Raw data and principal analyses.

Percent Endorsement of old items in recognition and familiarity tasks.

14 MILLISECONDS 42 MILLISECONDS 1 5 10 1 5 10 List Rec. Fam. Rec. Fam. Rec. Fam. Rec. Fam. Rec. Fam. Rec. Fam. A 1 70 20 20 50 40 20 60 60 20 70 50 60 3 60 50 50 50 50 20 50 60 50 50 50 40 5 50 10 60 50 50 60 80 60 70 30 60 40 7 40 20 60 60 60 60 70 40 40 30 50 60 9 40 40 60 40 40 50 50 40 50 50 60 70 11 50 40 50 70 80 50 50 40 50 70 50 60 13 40 50 50 60 40 30 50 70 40 60 40 90 List B 2 50 70 50 40 80 60 90 10 20 70 40 30 4 60 30 80 20 40 60 40 40 20 50 30 40 6 70 50 30 30 40 20 40 50 30 60 70 60 8 50 50 10 80 40 60 20 50 50 40 50 40 10 60 40 60 40 40 50 60 30 50 40 70 40 12 60 60 90 50 70 60 20 40 20 60 50 20 14 90 30 50 70 50 80 40 40 60 30 60 20 15 30 50 50 40 40 60 70 60 60 30 30 60

Analysis of variance table: Experiment 2

Source SumSQ df MSQ F

LIST 332.233 1 332.233 3.02 ERROR 1431.101 13 110.085

QUESTION 405.000 1 405.000 1.15 ERROR 4569.196 13 351.477

DURATION 67.222 1 67.222 0.14 ERROR 6160.863 13 473.913

1 vs 5 REPS 3.333 1 3.333 0.02 ERROR 1957.366 13 150.567

(1&5) vs 10 REPS 90.000 1 90.000 0.94 ERROR 1249.479 13 96.114

227 Appendix c (Cont'd)

Source SumSQ df MSQ F

QUEST. X DURAT 293.889 1 293.889 0.85 ERROR 4513.244 13 347.173

QUEST. X(1VS5) 1333.333 1 1333.333 5.28 ERROR 3285.938 13 252.764

QUEST X (1&5V10) 40.000 1 40.000 0.14 ERROR 3722.099 13 286.315

DURAT. X (1VS5) 333.333 1 333.333 1. 65 ERROR 2632.366 13 202.490

DURAT X (1&5V10) 17.778 1 17.778 0.08 ERROR 2992.932 13 230.226

DUR.X QUES X(1V~) 1333.333 1 1333.333 5.28 ERROR 3285.938 13 252.764

DURxQUESX(1&5V10) 187.778 1 187.778 1. 00 ERROR 2436.979 13 187.460

228 Appendix D. Stimulus List: Experiments 3 and 4 High Frequency Low Frequency Nonwords PALLERITE MACHINE KEROSENE SHESTIN MOURLY SCIENCE BACHELOR POCUST BE SNAPE PICTURE GAZETTE PRAPBOOK GRAVIST SUPPORT HYDRANT PRE GONER PAS PER CONTROL RAINBOW EMPELLOR PLAGILE SERVICE CHUTNEY FUESTED MOOKLE PRESSURE MIGRAINE TARGENT HELLEROW SEVERAL VERANDAH ENMARGLE AGAGE SOCIETY PHAROAH DURBLINE PRIMUDE INDUSTRY ANTIQUE TYLLIC GORRIDGE FUNCTION INCISION WRASTER CLIMPATE KITCHEN CROQUET SHUCKEN TRAFTED BROUGHT DELIRIUM APPICISE DENANTIC EVERYONE CUTLERY PARRENTILE ACCORST CAPTAIN CYANIDE TAUGHER TEMTOSE FAILURE INFERNO MOLASITE CABULE HUSBAND CHIMNEY HALUMEN ABLITARY CURRENT AVOCADO VELENT FRANGUAL PURPOSE BRAVADO NIMICATER MAPULE PRIVATE RUFFIAN LYMANEDE CHAFFLE BECAUSE INSOMNIA BUDENISM TOWPACE COUNTRY BASSOON MIRALOSE PULLAPE PATTERN LEXICON SELSARY TEGENSARY STANDARD LITHIUM ALLUNURY BLAMPHY EXAMPLE ATROCITY PAS TONE TACRINILE DIRECTOR ALLEGORY PARTLER ALLIFRIGANT FREEDOM CINAMMON HESTEN POISANT ORIGINAL MONOGRAM GOLLICE FLEBUTILE MILITARY FLAMINGO TRAMBLE INGUINE CONSIDER ANTIDOTE PRANTLY IMPEROR COMPANY WARRANTY UNGAFE ENTRATE DECISION BROCCOLI MELLICATE RENGULOUS SERIOUS BAYONET DEBLAGE AVERAGE APRICOT MOSSLE BUSINESS MEMBRANE TRAFTAGE DISTRICT VENDETTA MIDEITY APPROACH EXPONENT LOSPITE HIMSELF SEXTANT HAMEAGE WITHOUT HYACINTH ANDRASTE VARIOUS BULLOCK DEMANSE

229 Appendix E. Experiment 3: Raw data and principal analyses. Experiment 3. Lexical Decision Times

New Simple Rep. Response Rep. High Low Non. High Low Non. High Low Non. Freq. Freq Freq. Freq Freq. Freq List A 1 628 706 823 604 683 880 612 590 701 3 648 807 769 629 650 785 624 673 748 5 498 595 624 518 543 623 476 506 654 7 720 829 986 583 695 975 630 707 971 9 716 776 775 669 794 826 740 601 706 11 498 548 683 480 532 652 473 494 575 12 549 780 1023 536 615 1073 501 587 948 14 666 777 816 628 682 820 618 699 742 16 728 862 1107 703 878 1082 700 867 864 18 646 733 811 578 664 904 532 533 715 20 760 834 863 712 912 896 503 544 710 22 523 760 719 526 608 738 534 571 693 24 786 795 816 644 727 845 709 714 825 26 701 865 1295 626 774 1199 612 724 939 28 591 725 785 581 620 743 654 581 687 30 772 845 976 965 779 1055 660 775 917

List B 2 599 725 915 545 612 906 677 579 814 4 644 672 774 559 573 774 600 501 605 6 792 929 1038 825 946 1097 786 842 978 8 546 581 650 527 600 653 504 566 592 10 658 927 895 586 840 94 6 614 776 844 13 4 7 6 533 582 441 461 685 444 454 576 15 489 530 625 466 514 590 532 492 558 17 546 627 824 521 492 821 512 526 728 19 568 744 757 546 758 730 551 819 807 21 661 811 862 666 763 971 612 664 860 23 607 683 8 64 469 639 853 403 461 638 25 543 652 807 438 590 713 464 545 672 27 795 990 1070 941 1035 1233 883 1246 900 29 843 1030 1111 832 840 1019 718 801 811 31 516 687 841 523 508 768 499 489 718 32 640 730 901 528 544 879 506 530 720

231 Analysis of Variance Summary: Experiment 3.

SOURCE SumSQ df MeanSQ F

LIST 50416.66796875 1 50416.66796875 0.280 ERROR 5398654.5 30 179955.15625

FREQUENCY 315657.4375 1 315657.44 52.359 ERROR 180861.484375 30 6028.73

LEXICALITY 1963151.25 1 1963151.25 118.403 ERROR 497406.21875 30 16580.20703125

#PRESENTATIONS 213906.25 1 213906.25 41.034 ERROR 156387.40625 30 5212.913

#RESPONSES 326612.25 1 326612.25 47.082 ERROR 208113.296875 30 6937.10986328125

FREQXPRES. 30459.375 1 30459.375 18.591 ERROR 49152.91796875 30 1638.4305

FREQXRESP. 24432.2109375 1 24432.2109375 9.276 ERROR 79021.6640625 30 2634.055

LEX X PRES 5995.125 1 5995.125 2.762 ERROR 65122.484375 30 2170.74951

LEXXRESP. 35013.1953125 1 35013.1953125 9.068 ERROR 115837.25 30 3861.2417

232 Experiment 3: Participant percent errors.

New Simple Rep. Response Rep. High Low Non. High Low Non. High Low Non. Freq. Freq Freq. Freq Freq. Freq List A 1 0 0 5 0 0 0 0 0 3 0 0 0 0 0 10 0 0 5 0 10 0 0 0 10 0 10 7 0 0 10 0 30 15 10 20 9 0 20 5 0 20 10 0 10 11 0 0 20 0 0 20 0 0 12 0 20 5 0 0 20 0 10 14 10 0 0 0 0 25 0 20 16 10 0 0 0 0 10 0 20 18 0 10 10 0 10 20 0 10 20 10 30 10 0 0 0 0 10 22 0 30 20 0 10 20 0 20 24 0 0 0 0 0 10 0 0 26 0 0 40 0 0 35 0 20 28 0 0 0 0 0 10 0 10 30 0 0 0 0 0 20 0 10

List B 2 0 0 5 10 0 30 0 0 4 0 10 15 0 0 15 0 30 6 0 0 0 0 10 15 0 0 8 0 20 0 0 10 10 0 20 10 10 30 5 0 0 0 0 50 13 0 20 10 0 0 15 0 0 15 0 0 10 0 20 45 0 0 17 0 10 0 0 0 30 0 0 19 20 0 5 10 10 15 0 0 21 0 10 25 0 10 35 0 30 23 0 30 5 0 0 15 0 10 25 0 40 0 0 10 10 0 30 27 20 0 15 10 10 25 10 20 29 0 10 10 0 0 5 0 0 31 0 10 10 0 0 15 0 0 32 0 0 15 20 0 15 0 10

233 Experiment 3: Errors: Analysis of Variance Summary Table

SOURCE SumSQ df MeanSQ F

LIST 461652.46875 1 461652.469 1.696 ERROR 4898353.5 18 272130.75

FREQUENCY 232672.140625 1 232672.14 27.132 ERROR 154360.5625 18 8575.587

LEXICALITY 718954.875 1 718954.875 27.896 ERROR 463916.6875 18 25773.1484375

#PRESENTATIONS 275006.9375 1 275006.9375 31.730 ERROR 156007.296875 18 8667.072265625

#RESPONSES 1192436 1 1192436 51.807 ERROR 414305.3125 18 23016.960

FREQXPRES. 5096.81689 1 5096.81689 1.458 ERROR 62925.828125 18 3495.879

FREQXRESP. 109824.820 1 109824.820 17.525 ERROR 112804.0703125 18 6266.8926

LEX X PRES 14996.9384765625 1 14996.93845 5.873 ERROR 45965.2734375 18 2553.6262

LEXXRESP 18200.5546875 1 18200.555 3.441 ERROR 95211.6953125 18 5289.53857421875

234 Appendix F. Experiment 4. Raw data and principal analyses.

Experiment 4. Lexical Decision Times

New Simple Rep. Response Rep. High Low Non. High Low Non. High Low Non. Freq. Freq Freq. Freq Freq. Freq List A 1 628 706 823 604 683 880 612 590 701 3 648 807 769 629 650 785 624 673 748 5 498 595 624 518 543 623 476 506 654 7 720 829 986 583 695 975 630 707 971 9 716 776 775 669 794 826 740 601 706 11 498 548 683 480 532 652 473 494 575 12 549 780 1023 536 615 1073 501 587 948 14 666 777 816 628 682 820 618 699 742 16 728 862 1107 703 878 1082 700 867 864 18 646 733 811 578 664 904 532 533 715 20 760 834 863 712 912 896 503 544 710 22 523 760 719 526 608 738 534 571 693 24 786 795 816 644 727 845 709 714 825 26 701 865 1295 626 774 1199 612 724 939 28 591 725 785 581 620 743 654 581 687 30 772 845 976 965 779 1055 660 775 917

List B 2 599 725 915 545 612 906 677 579 814 4 644 672 774 559 573 774 600 501 605 6 792 929 1038 825 946 1097 786 842 978 8 546 581 650 527 600 653 504 566 592 10 658 927 895 586 840 946 614 776 844 13 476 533 582 441 461 685 444 454 576 15 489 530 625 466 514 590 532 492 558 17 546 627 824 521 492 821 512 526 728 19 568 744 757 546 758 730 551 819 807 21 661 811 862 666 763 971 612 664 860 23 607 683 864 469 639 853 403 461 638 25 543 652 807 438 590 713 464 545 672 27 795 990 1070 941 1035 1233 883 1246 900 29 843 1030 1111 832 840 1019 718 801 811 31 516 687 841 523 508 768 499 489 718 32 640 730 901 528 544 879 506 530 720

235 Analysis of Variance Summary: Lexical Decision Time. Experiment 4.

SOURCE SumSQ df MeanSQ F

LIST 50416.66796875 1 50416.66796875 0.280 ERROR 5398654.5 30 179955.15625

FREQUENCY 315657.4375 1 315657.44 52.359 ERROR 180861.484375 30 6028.73

LEXICALITY 1963151.25 1 1963151.25 118.403 ERROR 497406.21875 30 16580.20703125

#PRESENTATIONS 213906.25 1 213906.25 41.034 ERROR 156387.40625 30 5212.913

#RESPONSES 326612.25 1 326612.25 47.082 ERROR 208113.296875 30 6937.10986328125

FREQXPRES. 30459.375 1 30459.375 18.591 ERROR 49152.91796875 30 1638.4305

FREQXRESP. 24432.2109375 1 24432.2109375 9.276 ERROR 79021.6640625 30 2634.055

LEX X PRES 5995.125 1 5995.125 2.762 ERROR 65122.484375 30 2170.74951

LEXXRESP. 35013.1953125 1 35013.1953125 9.068 ERROR 115837.25 30 3861.2417

236 Experiment 4: Participant percent errors.

New Simple Rep. Response Rep. High Low Non. High Low Non. High Low Non. Freq. Freq Freq. Freq Freq. Freq List A 1 0 0 5 0 0 0 0 0 3 0 0 0 0 0 10 0 0 5 0 10 0 0 0 10 0 10 7 0 0 10 0 30 15 10 20 9 0 20 5 0 20 10 0 10 11 0 0 20 0 0 20 0 0 12 0 20 5 0 0 20 0 10 14 10 0 0 0 0 25 0 20 16 10 0 0 0 0 10 0 20 18 0 10 10 0 10 20 0 10 20 10 30 10 0 0 0 0 10 22 0 30 20 0 10 20 0 20 24 0 0 0 0 0 10 0 0 26 0 0 40 0 0 35 0 20 28 0 0 0 0 0 10 0 10 30 0 0 0 0 0 20 0 10

List B 2 0 0 5 10 0 30 0 0 4 0 10 15 0 0 15 0 30 6 0 0 0 0 10 15 0 0 8 0 20 0 0 10 10 0 20 10 10 30 5 0 0 0 0 50 13 0 20 10 0 0 15 0 0 15 0 0 10 0 20 45 0 0 17 0 10 0 0 0 30 0 0 19 20 0 5 10 10 15 0 0 21 0 10 25 0 10 35 0 30 23 0 30 5 0 0 15 0 10 25 0 40 0 0 10 10 0 30 27 20 0 15 10 10 25 10 20 29 0 10 10 0 0 5 0 0 31 0 10 10 0 0 15 0 0 32 0 0 15 20 0 15 0 10

D

237 Analysis of Variance Summary:Experiment 4. Errors

SOURCE SumSQ df MeanSQ F

0 LIST 51.04166793823242 1 51.041668 0.340 D ERROR 4507.29150390625 30 150.243057

FREQUENCY 2408.33325195 1 2408.333 23.432 ERROR 3083.333251953125 30 102.7778

LEXICALITY 2216.84033203125 1 2216.8403 15.568 ERROR 4271.875 30 142.3959

#PRESENTATIONS 17.36111068725586 1 17.36111 0.255 ERROR 2046.354125976562 30 68.21181

#RESPONSES 5.251736164 1 5.25173 0.119 ERROR 1322.135375976562 30 44.071178

FREQ X PRES. 0.260416656 1 0.260416656 0.005 ERROR 1693.229126 30 56.4409714

FREQ X RESP 356.51040 1 356.51040 6.635 ERROR 1611.979125976562 30 53.732639

LEX X PRES. 514.67017 1 514.67017 12.951 ERROR 1192.1875 30 39.7395821

LEX X RESP 401.388885 1 401.388885 8. 679 ERROR 1387.5 30 46.25

238 Appendix G: Stimulus Items; Experiments 5 and 6.

List A ListB List A ListB High Nonwords Distractor Distractor Frequency words Nonwords MAIL SMOKE RASTE PATIVE VERSE FARMER PIRRON CLABE THROAT MUSCLE PARTLE BROIN DESERT SPHERE SLANT DRACE MOTOR BEAR HILF KINE GENIUS FLUX BUNTH APLET NOVEL UNCLE MAND TUMP CRASH CRAFT BAWE BILIUM ARTIST MEAT SQUANE SHEAB HATRED CREAM WERRER SPLAG AVENUE CIRCLE ARGLE PALARY COLONY SLAVE ANGE GORCE CHEST BUREAU DUNIC GRAKE WORKER LIFT ESTOR TEPATE TOOL IRON FUTTER JILE JUMP FIST UPLADE GROID GOLD WEAPON JUSK REDAR GULF RITUAL ABRENT TUNCH COOK ENGINE SCANE FOUCH ENTRY VICTIM SABE GILP ROOF PICK FICE DRIND MIRROR BATH LOSH YOLL GUARD FORT HENT SOAT TAIL BORE TRIANT JINE DIRT PRISON SPURS GARE BOWL CROP GOPT REGER POCKET DRIVER MELL CRAT BELLY SWEAT TRAGH EXATH ESTATE WIRE WOZE PANK PLUG BUNDLE EMSATE PRACE SUIT LIQUID GREAT WHACE ROOT ACTOR STOUNT JOID LAKE SOIL SERDEN SALK SIXTY SAVING ARBE PO IT BRUSH CROSS PINUCE HOLK TOOTH ZERO CRENCH DOlTS SEAT WHEEL SARL STU ME CRITIC PLATE OCLATE BROST MATCH MILK BRARL YILP KETTLE DRUG PORGLE LOIX MOON BRAIN LAGE RAWT BUTTER CABIN PRASE TRITH SMILE QUEEN FRINE NEVICE REFORM MELODY CLOUP NIME CLOTH STEEL SOAD RUNGLE FENCE GRAIN LOJE QUILE DOLLAR CROWD NOFE GASK PLANET STAKE SPALL PABE BAND LAWYER TERP SPEET BEND HOLDER BUST CARIST LowFreq. BROLB INSH CHIN LOOP SPLAIN SNARF CRYPT SLAP SQUEAR PARON MERCY TALE GOUSE PILLEY FLUTE WALRUS PRAIF TREBOR LOBBY PALM PLAIL FRACE NAVEL DAMSEL RETE BURVE SHAME POND NORE GLOOT SKATE HARE GYRANT TEME TRIM COMBAT POING PARKET SPIKE SHRUB LUDDER POLO SAVAGE TIRE FINT TARK MOTH FROWN GOAM BRENTH POWDER INJURY QUARD SPART SIREN KNOB HOTICE ZAVE CRACK PITCH TELLET WABE DIAL ROBBER PIXER GOLE PADDER CLOCK PERNE INTANE BIRCH CROW SOOD BOAF FOIL TRAP CHANK SAST GROCER YAWN BINGER WOME STABLE DIET HAPPED ESP IRE FIDDLE HEROIN BRANK FISTH AUNT WIDOW KNAGE HINNER SNAIL STAIR ROUSIN LEXT MEAL VACUUM INCATE CLITH PRUNE PUDDLE FASH SICE DIVE MOTIVE STOlL CLUME LILY VAULT VEAL MOWL PILE POUND SLAFE AMMLE UMPIRE MORGUE LOOD BAST WARD MERIT GLAPE POUTH LARK BLUSH NORCH DREE CARD RANK DOKE MOIN GIRDLE SLEET BRUCK STIN ACCESS GANG MARNGE PLABO MAIDEN HEDGE GRALL TING PORT CHARM GARGER NUBE CARROT LEAK ALMOUR SNOP MOVIE SHADE SPEEM MANGLE BEGGAR FAWN BLESH HOAT HONEY HARM SHRAW GASE CUBE PLIERS THONE RALT THRUST MATE NERT SPLODE MINER CAVERN SEEB SHIPE MARBLE SAUCE CLAIN POINCE CAMEL HIVE SNAGE NOKE SOAP SHELL INTLE DEARF HOCKEY MADMAN SPONE BREAL FLOWER BELT GEND SPLANE NYMPH MUCUS

239 Appendix H. Experiment 5: Raw data and principal analyses.

Experiment 5: lexical Decision Time data. New Simple Repetition Response Repetition High Low Non High Low Non High Low Non 1 657 636 710 591 664 698 592 583 639 2 733 756 797 681 821 760 733 677 686 3 795 921 1000 810 841 912 756 808 877 4 677 858 883 645 711 933 606 617 788 5 680 694 773 620 658 799 588 585 685 6 696 953 928 740 780 921 667 747 840 7 684 834 1017 690 761 923 646 704 700 8 724 850 1270 786 790 1271 668 765 1033 9 750 821 899 768 733 841 729 777 814 10 678 747 835 555 656 876 522 594 743 11 824 848 864 779 806 825 732 797 719 12 837 1006 1067 782 922 1055 796 731 906 13 754 906 928 807 797 869 774 850 813 14 651 731 826 660 647 847 600 656 707 15 841 853 847 798 786 853 714 763 743 16 627 716 782 608 605 821 528 618 741 17 797 793 903 715 805 820 627 722 768 18 608 685 756 619 623 732 538 575 643 19 1029 1349 1317 893 1056 1302 869 791 992 20 636 754 827 668 640 858 595 619 725 21 678 750 793 657 756 714 642 663 661 22 626 743 733 612 648 733 601 634 681 23 734 995 1012 785 939 1084 678 885 912 24 694 670 778 628 602 798 610 631 674 25 802 924 971 810 897 1057 683 831 904 26 708 758 785 650 672 804 634 644 689 27 720 787 763 690 743 769 729 723 719 28 1126 1408 1573 1042 1259 1636 929 814 905 29 610 818 1266 607 646 1275 658 656 857 30 694 897 784 716 810 780 659 697 718 31 684 950 913 692 789 921 596 644 835

ANALYSIS OF VARIANCE TABLE: Experiment 5 Lexical Decision Time.

Source SumSQ df MeanSQ F

FREQUENCY 228410.34375 1 228410.34375 70.848 ERROR 96718.3203125 30 3223.944091796875

LEXICALITY 1100089.875 1 1100089.875 48.638 ERROR 678536.0625 30 22617.869140625

240 ANALYSIS OF VARIANCE TABLE: Lexical Decision Time (Cont.d).

PRESENT 1V2 374664.3125 1 374664.3125 64.557 ERROR 174108.5625 30 5803.61865234375

RESPONSE 645932.3125 1 645932.3125 49.418 ERROR 392126.1875 30 13070.873046875

FREQXPRES. 20124.015625 1 20124.015625 8.614 ERROR 70088.8125 30 2336.293701171875

LEX X PRES. 403.4417419433594 1 403.4417419433594 0.204 ERROR 59415.140625 30 1980.504638671875

FREQ X RESP. 156087.09375 1 156087.09375 66.613 ERROR 70295.40625 30 2343.18017578125

LEXXRESP. 51402.7578125 1 51402.7578125 11.498 ERROR 134118.40625 30 4470.61376953125

ANALYSIS OF VARIANCE TABLE: Lexical Decision Errors.

FREQUENCY 1871.50537109375 1 1871.50537109375 15.545 ERROR 3611.8271484375 30 120.3942413330078

LEXICALITY 86.73834991455078 1 86.73834991455078 0.804 ERROR 3235.483642578125 30 107.8494567871094

PRESENT. 265.6361999511719 1 265.6361999511719 7.396 ERROR 1077.419311523438 30 35.91397857666016

RESPONSE 346.9533996582031 346.9533996582031 10.582

ERROR 983.602294921875 30 32.7867431640625

FREQ. X PRES. 103.2258071899414 1 103.2258071899414 3.073 ERROR 1007.885314941406 30 33.59617614746094

LEX. X PRES. 8.960573375225067E-002 1 8.960573375225067E-002 0.003 ERROR 836.021728515625 30 27.86739158630371

FREQ. X RESP. 1512.096801757812 1 1512.096801757812 14.973 ERROR 3029.569580078125 30 100.9856491088867

LEX. XRESP. 86.11111450195312 1 86.11111450195312 3.974 ERROR 650 30 21.66666603088379

241 Experiment 5: Perceptual identification data.

Proportion gain from prior exposure (against new items) 1POR 1P1R 2POR 2P2R 2P2R high low non high low non High Low Non high low non High low non Au d. 1 0.4 -0.3 0.1 -0.2 -0.3 0.4 0.6 0.1 -0.1 0.6 0.1 0 0.2 0.1 0.1 3 0 0.1 0.2 0.2 0.3 0.2 0.2 -0.1 0.1 0.4 0.3 0.2 0.2 0.3 0.2 5 0.3 0.1 0 0.1 -0.1 0.3 0.1 -0.1 0.1 0.1 0.1 0.2 0.1 -0.3 0 7 0.3 -0.1 -0.05 0.1 0.3 0.15 -0.1 -0.1 -0.05 0.1 -0.1 0.25 0.5 -0.3 0.05 9 0.2 0.6 0.05 0.4 0.6 0.15 0.4 0 0.05 0.2 0.4 0.35 0.4 0.4 -0.05 11 0.1 0.1 -0.05 0.1 0.5 0.05 -0.1 0.1 0.25 0.1 0.1 0.25 0.7 0.3 -0.25 13 0.4 0.2 0.1 0.4 0.2 0.7 0.2 0.2 0.2 0 0.2 0.4 0 0.2 0.2 15 0.2 0.5 0.25 0.6 0.3 0.65 0.4 0.1 0.65 0.4 0.5 0.55 0.4 0.3 0.25 17 -0.1 -0.2 -0.05 -0.1 0 -0.05 -0.5 -0.2 0.05 0.1 0.2 0.05 -0.1 0.2 0.15 19 0.4 0.4 0.15 0.2 0.2 0.25 0.2 0.4 0.25 0.4 0.4 0.15 0.2 0.2 -0.05 21 0.2 0.6 -0.2 0.2 0.2 0.1 0.2 0.4 -0.2 -0.2 0.6 0 0.2 0.6 0.2 23 0.3 0.5 0.05 0.3 0.3 0.25 0.3 0.3 0.25 0.1 0.5 -0.05 0.3 0.5 0.05 25 0.4 0.5 0.4 0.4 0.1 0.6 0.6 0.3 0.3 0.6 0.1 0.5 0.6 0.5 0.6 27 0 0 0.15 0 0.4 0.05 0 0.2 0.15 -0.2 0.6 0.15 0.4 0.2 0.35 29 0.3 0.4 0.15 0.5 0.6 0.45 0.5 0.6 0.65 0.5 0.6 0.45 0.5 0.8 0.45 liistB 2 -0.2 -0.1 0.35 -0.2 0.1 0.25 -0.2 -0.1 0.25 0 0.1 0.25 0 0.3 0.35 4 -0.2 0.2 0.2 0.2 0.4 0.5 -0.2 0 0.4 0 0 0.4 0 0.2 0.4 6 0.1 0 -0.05 0.1 0.6 0.05 0.1 0 -0.05 -0.1 0.2 0.35 0.3 0.6 0.15 8 0.4 -0.1 0.4 0.6 0.1 0.3 0.4 0.3 0.2 0.4 0.1 0.1 0.2 0.7 0.4 10 0.2 -0.2 0.1 0.4 -0.2 0.2 0.4 -0.4 0.2 0.2 0 0.2 0.2 0.2 0.2 12 0.5 -0.1 -0.15 0.1 -0.1 -0.05 0.3 -0.1 -0.15 0.3 0.1 0.05 0.3 0.3 -0.15 14 0.4 -0.2 0.3 0.8 0.4 0.1 0.8 0.6 0 0.6 0.8 0.2 0.6 0.6 0.2 16 0.2 -0.1 0.4 0.4 0.1 0 0.4 0.1 0 0.6 -0.3 0.1 0.4 -0.1 0.2 18 -0.1 0.1 0.3 0.1 0.3 0.2 0.1 0.1 0.3 0.3 0.5 0.2 0.3 0.5 0.3 20 0 0.2 -0.05 0.2 0.2 0.15 0.2 0.4 -0.05 0 0.2 0.05 0.2 0.2 -0.05 22 0.2 0 0 0.6 0.8 0 0.2 0 0 0.6 0.4 0 0.6 0.6 0 24 0.2 -0.3 0.25 0.4 0.1 0.25 0.4 -0.1 0.05 0.2 -0.1 -0.05 0.4 0.1 0.15 26 0.7 0.3 0.15 0.5 -0.1 0.05 0.3 -0.1 0.05 0.7 0.1 0.25 0.3 0.5 0.15 28 -0.1 -0.1 0.15 -0.1 0.1 0.35 -0.1 0.1 0.35 0.1 0.3 0.15 0.1 0.1 0.45

ANALYSIS OF VARIANCE TABLE: Perceptual Identification.

Source SumSQ df MeanSQ F

List .1148989722132683 1 .1148989722132683 0.497

ERROR 6.245468616485596 27 .2313136458396912

Frequency .1456896960735321 1 .1456896960735321 1.139 ERROR 3.453861951828003 27 .1279208064079285

Lexicality .1853908896446228 1 .1853908896446228 1.524 ERROR 3.28495264053344 7 27 .1216649115085602

Resp ov1 6.47508651 0181427E-002 1 6.47508651 0181427E-002 2.467 ERROR .7087069153785706 27 2.624840475618839E-002

Resp Ov{1or2) .882758617401123 1 .882758617401123 30.840 ERROR .7728444337844849 27 2.862386777997017E-002

242 Experiment 5: Recognition and Exclusion data.

Critical Items: Item retrieval (percent).Recognition

1POR 2POR 1P1R 2P1R 2P2R High Low Non High Low Non High Low Non High Low Non High Low 42.9 0 28.6 14.3 0 0 42.9 28.6 0 42.9 42.9 28.6 14.3 28.6 14.3 28.6 28.6 14.3 14.3 42.9 14.3 42.9 14.3 28.6 14.3 14.3 42.9 14.3 0 28.6 0 28.6 0 14.3 28.6 28.6 0 14.3 0 14.3 0 0 14.3 14.3 28.6 28.6 28.6 14.3 14.3 42.9 0 28.6 14.3 14.3 14.3 28.6 100 0 42.9 14.3 28.6 28.6 42.9 0 0 28.6 28.6 0 57.1 14.3 42.9 14.3 14.3 42.9 42.9 0 42.9 28.6 42.9 14.3 42.9 0 0 28.6 28.6 28.6 100 42.9 28.6 14.3 14.3 28.6 0 42.9 0 14.3 14.3 28.6 0 14.3 14.3 28.6 14.3 28.6 28.6 42.9 28.6 14.3 28.6 28.6 42.9 28.6 42.9 14.3 14.3 28.6 0 0 28.6 0 28.6 57.1 0 28.6 14.3 28.6 28.6 0 14.3 42.9 57.1 14.3 28.6 0 14.3 28.6 28.6 0 14.3 28.6 14.3 42.9 28.6 42.9 28.6 85.7 14.3 42.9 28.6 28.6 28.6 28.6 28.6 28.6 28.6 42.9 14.3 14.3 28.6 28.6 0 28.6 28.6 14.3 0 14.3 14.3 28.6 42.9 28.6 42.9 42.9 28.6 28.6 28.6 42.9 14.3 28.6 42.9 85.7

244 Recognition Exclusion.

1POR 2POR 1P1R 2P1R 2P2R High Low Non High Low Non High Low Non High Low Non High Low 50 33.3 33.3 16.7 33.3 33.3 50 83.3 83.3 33.3 50 33.3 83.3 83.3 33.3 16.7 16.7 33.3 33.3 0 50 66.7 33.3 83.3 83.3 33.3 83.3 33.3 33.3 33.3 33.3 33.3 33.3 0 16.7 83.3 33.3 50 83.3 66.7 50 83.3 16.7 0 0 33.3 50 16.7 66.7 50 33.3 66.7 50 50 66.7 66.7 33.3 16.7 16.7 0 0 0 33.3 66.7 50 33.3 66.7 50 66.7 50 66.7 11.1 0 66.7 66.7 16.7 77.8 77.8 66.7 77.8 100 16.7 100 100 66.7 22.2 33.3 33.3 55.6 0 66.7 77.8 16.7 66.7 77.8 33.3 88.9 44.4 44.4 33.3 33.3 22.2 55.6 16.7 55.6 55.6 50 44.4 100 66.7 66.7 88.9 22.2 55.6 33.3 33.3 44.4 16.7 88.9 44.4 33.3 100 44.4 16.7 100 77.8 66.7 22.2 16.7 33.3 55.6 50 77.8 77.8 16.7 55.6 66.7 33.3 100 77.8 33.3 22.2 33.3 22.2 44.4 33.3 66.7 77.8 11.1 55.6 55.6 55.6 44.4 77.8 33.3 33.3 33.3 44.4 33.3 44.4 22.2 22.2 44.4 55.6 33.3 22.2 33.3 44.4 44.4 44.4 33.3 33.3 44.4 44.4 77.8 44.4 44.4 22.2 33.3 44.4

245 Experiment 5: New and auditory study items: item means.

RECOGNITION RECOGNITION EXCLUSION New Words NewN/Ws Aud. Words Aud. N/Ws New Words NewN/Ws Aud. Words Aud. N/Ws 28.6 14.3 28.6 71.4 0 16.7 33.3 50 14.3 14.3 28.6 42.9 16.7 16.7 50 33.3 28.6 28.6 14.3 42.9 16.7 16.7 16.7 33.3 14.3 14.3 14.3 71.4 0 33.3 16.7 33.3 14.3 0 14.3 57.1 0 33.3 16.7 66.7 0 0 42.9 28.6 33.3 16.7 16.7 33.3 42.9 14.3 57.1 14.3 16.7 16.7 0 33.3 42.9 14.3 28.6 71.4 16.7 16.7 16.7 50 57.1 0 14.3 42.9 33.3 0 33.3 16.7 28.6 14.3 28.6 42.9 33.3 0 0 16.7 0 0 28.6 14.3 16.7 0 16.7 16.7 0 14.3 28.6 57.1 16.7 0 16.7 16.7 14.3 14.3 28.6 57.1 16.7 16.7 16.7 33.3 0 28.6 42.9 57.1 16.7 16.7 16.7 33.3 28.6 14.3 14.3 71.4 33.3 16.7 0 33.3 28.6 0 28.6 71.4 0 0 50 0 28.6 0 28.6 42.9 0 0 0 33.3 0 14.3 28.6 42.9 50 0 33.3 50 28.6 28.6 57.1 42.9 33.3 0 16.7 16.7 0 28.6 28.6 42.9 0 50 0 33.3 57.1 0 28.6 71.4 33.3 0 0 14.3 28.6 57.1 33.3 0 0 0 42.9 57.1 0 16.7 28.6 14.3 57.1 57.1 0 33.3 28.6 0 42.9 42.9 16.7 33.3 0 0 42.9 57.1 66.7 16.7 14.3 0 42.9 57.1 0 16.7 14.3 85.7 57.1 71.4 16.7 33.3 28.6 0 14.3 42.9 0 33.3 42.9 14.3 42.9 71.4 33.3 0 28.6 14.3 28.6 57.1 55.6 22.2 14.3 28.6 57.1 71.4 22.2 0 0 42.9 28.6 57.1 11.1 33.3 42.9 57.1 57.1 85.7 22.2 11.1 71.4 57.1 42.9 57.1 11.1 33.3 42.9 14.3 28.6 57.1 22.2 22.2 28.6 57.1 14.3 14.3 11.1 66.7 28.6 28.6 42.9 28.6 33.3 33.3 14.3 28.6 42.9 42.9 33.3 33.3 57.1 42.9 14.3 42.9 0 44.4 28.6 28.6 55.6 11.1 57.1 71.4 33.3 22.2 42.9 28.6 11.1 11.1 28.6 14.3 22.2 11.1 71.4 42.9 33.3 44.4 57.1 42.9 11.1 33.3 28.6 42.9 22.2 0 0 14.3 55.6 44.4 28.6 28.6 55.6 22.2 42.9 28.6 0 55.6 28.6 57.1 44.4 22.2 28.6 14.3 55.6 0 14.3 14.3 11.1 0 28.6 42.9 44.4 22.2 57.1 71.4 0 33.3 0 28.6 66.7 11.1 14.3 42.9 22.2 11.1 42.9 28.6 22.2 77.8 14.3 14.3 0 44.4 42.9 42.9 22.2 11.1

246 ANALYSIS OF VARIANCE TABLE:Recognition

Source SumSQ dfMeanSQ F Frequency 19.360 1. 000 19. 360 0.058 Lexicality 15576.120 1.000 15576.120 46.770 Response Ov1 3014.015 1.000 3014.015 9.050 Present. 1v2 33213.445 1.000 33213.445 99.729 Response 1v2 1676.679 1.000 1676.679 5.034 Freq X Pres 1v2 482.406 1. 000 482.406 1. 449 Freq X resp Ov1 284.282 1. 000 284.282 0.854 Freq X resp 1v2 1414.533 1.000 1414.533 4.247 Lex X Pres 1 v2 728.521 1.000 728.521 2.187 Lex X Resp Ov13383.521 1.000 3383.521 10.160 Lex X Resp 1v2 275.204 1. 000 27 5. 204 0.826

ERROR 126887.625 381.0 333.038

ANALYSIS OF VARIANCE TABLE:Recognition Exclusion

Source SumSQ dfMeanSQ F

Frequency 1354.240 1.000 1354.240 4.109 Lexicality 84.500 1. 000 84.500 0.256 Response Ovs1 3.816 1. 000 3.816 0.012 Present 1 vs 2 0.901 1. 000 0.901 0.003 Response 1 vs 2 455.881 1.000 455.881 1.383 Freq X Pres 1v2 390.427 1.000 390.427 1.185 Freq X Resp Ov1 185.927 1.000 185.927 0.564 Freq X resp 1v2 360.533 1.000 360.533 1.094 Lex X Pres. 1v2 93.521 1.000 93.521 0.284 Lex X Resp Ov1 24.083 1.000 24.083 0.073 Lex X Resp 1v2 127.604 1.000 127.604 0.387

ERROR %125565.140625 381.0 329.567

ANALYSIS OF VARIANCE TABLE:'Recollection' estimates

Source SumSQ df MeanSQ F

Frequency 1689.209 1. 000 1689.209 2.896 Lexicality 13219.380 1. 000 13219.380 22.667 Response Ovs1 3336.966 1. 000 3336. 966 5. 722 Present 1 vs 2 33260.039 1. 000 33260.039 57.030 Response 1 vs 2 3896.400 1. 000 3896.400 6.681 Lex X Pres. 1v2 4.507 1. 000 4. 507 0.008 Lex X Resp Ov1 9.882 1.000 9.882 0.017 Lex X Resp 1v2 3100.833 1. 000 3100.833 5. 317

ERROR %222201.90625 381.000583.207

247 ANALYSIS OF VARIANCE TABLE: 'Familiarity' estimates

Source SumSQ df MeanSQ F

Frequency 1985.969 1. 000 1985.969 6.176 Lexicality 6819.619 1.000 6819.619 21.208 Response Ov1 2153.791 1. 000 2153.791 6.698 Present. 1v2 8068.434 1.000 8068.434 25.091 Response 1v2 938.521 1.000 938.521 2.919 Lex X Pres. 1v2 371. 358 1. 000 371.358 1.155 Lex X Resp Ov1 0.583 1. 000 0. 583 0.002 Lex X Resp 1v2 47.919 1.000 47.919 0.149

ERROR 122193.36 380.0 321.561

248 Appendix I. Experiment 6: Raw data and principal analyses. Experiment 6: Raw data: naming latencies.

New Simple Repetition Response Repetition High Low Non High Low Non High Low Non 1 509 501 649 468 546 600 512 492 541 2 742 765 900 710 779 891 714 648 774 3 759 771 872 803 758 936 759 720 794 4 742 794 866 776 746 937 683 715 847 5 623 730 793 638 642 748 628 665 683 6 796 887 876 744 861 950 729 616 824 7 622 655 718 667 679 772 628 623 707 8 627 636 731 566 626 717 586 620 640 9 804 882 957 764 990 968 686 683 789 10 617 661 760 621 626 780 601 618 719 11 649 702 720 612 672 708 624 617 685 12 758 684 845 711 695 849 646 654 716 13 757 841 911 854 805 896 835 715 787 14 621 654 725 613 638 769 698 578 650 15 656 713 811 658 756 795 648 608 702 16 509 517 562 483 537 577 439 483 520 17 762 796 815 774 771 857 742 800 819 18 531 514 556 535 527 601 503 483 543 19 781 817 932 822 783 954 752 786 850 20 639 637 704 695 717 763 663 655 710 21 829 805 1018 879 859 990 839 787 954 22 683 660 752 666 727 758 668 670 707 23 669 677 760 717 726 771 690 678 681 24 674 669 797 651 664 754 846 619 707 25 572 563 647 596 594 649 582 561 635 26 542 559 595 542 572 599 494 496 556

ANALYSIS OF VARIANCE TABLE: Naming ~atency.

Source SumSQ df MeanSQ F 1 3538.775634765625 1 3538.77563476 2.082 FREQ. 42484.390625 25 1699.375610351562

LEXICALITY394806.9375 1 394806.9375 203.52

ERROR 48495.44921875 25 1939.817993164062

PRESENT. 17908.173828125 1 17908.173828125 13.576

ERROR 32977.2109375 25 1319.08837890625

249 Experiment 6: Naming Latency (Cont.d)

RESPONSE 124558.171875 1 124558.171875 40.410 ERROR 77059.890625 25 3082.3955078125

PRES. X LEX 1947.115356445312 1 1947.115356445312 2.123 ERROR 22926.66015625 25 917.06640625

PRESX FREQ46.9262809753418 1 46.9262809753418 0.051 ERROR 22867.326171875 25 914.6930541992188

RESPXFREQ 20972.3203125 1 20972.3203125 10.707 ERROR 48970.51171875 25 1958.820434570312

RESPxLEX 14689.384765625 1 14689.384765625 16.526 ERROR 22221.2265625 25 888.8490600585938

Experiment 6: Recognition and Exclusion data.

Critical Items: Item retrieval (percent) Recognition 1POR 1P1R 2POR 2P1R 2P2R High Low Non High Low Non High Low Non High Low Non High Low Non 62.5 37.5 87.5 50 25 37.5 75 50 37.5 25 37.5 12.5 12.5 12.5 25 50 75 87.5 37.5 50 50 100 62.5 62.5 12.5 12.5 62.5 37.5 75 37.5 75 62.5 62.5 25 12.5 75 50 62.5 62.5 37.5 37.5 25 37.5 12.5 37.5 87.5 50 50 87.5 25 75 37.5 87.5 62.5 37.5 12.5 50 50 25 62.5 87.5 50 62.5 37.5 25 37.5 62.5 75 75 62.5 12.5 50 12.5 25 37.5 66.7 83.3 62.5 83.3 16.7 25 66.7 66.71 100 66.7 0 37.5 0 50 37.5 83.3 66.71 25 33.3 33.3 50 66.7 66.7 100 100 0 25 83.3 50 50 66.7 50 62.5 33.3 50 12.5 83.3 50 87.5 83.3 50 37.5 66.7 66.7 37.5 100 66.7 62.5 66.7 66.7 50 100 100 87.5 33.3 33.3 37.5 0 50 50 66.71 100 87.5 16.7 33.3 37.5 83.3 83.3 37.5 33.3 33.3 25 16.7 0 12.5 66.7 66.7 100 50 66.7 100 83.3 83.31 83.3 50 100 50 50 66.7 66.7 66.7 33.3 100 83.3 83.3 100 50 66.7 50 83.3 66.7 100 83.3 33.3 50 16.7 83.3 100 100 33.3 83.3 33.3 66.7 83.3 83.3 83.3 0 66.7 50 50 100 33.3 100 16.7 50

250 Recognition Exclusion 1POR 1P1R 2POR 2P1R 2P2R High Low Non High Low Non High Low Non High Low Non High Low Non 12.5 37.5 37.5 37.5 12.5 12.5 25 37.5 25 25 37.5 12.5 0 37.5 12.5 37.5 12.5 50 25 25 25 37.5 37.5 12.5 12.5 12.5 25 37.5 62.5 25 50 25 37.5 37.5 12.5 12.5 25 12.5 50 25 25 12.5 37.5 12.5 25 37.5 50 12.5 37.5 12.5 62.5 37.5 25 50 12.5 12.5 37.5 12.5 12.5 37.5 37.5 25 37.5 62.5 0 12.5 25 25 25 50 25 37.5 37.5 25 25 0 28.6 50 14.3 42.9 25 0 14.3 25 0 14.3 37.5 0 42.9 0 0 0 0 0 0 37.5 0 14.3 25 0 14.3 12.5 14.3 14.3 25 14.3 14.3 37.5 14.3 0 12.5 14.3 0 25 0 28.6 25 0 14.3 37.5 42.9 0 37.5 14.3 0 37.5 0 0 37.5 0 14.3 0 0 14.3 37.5 0 28.6 25 0 0 37.5 0 42.9 50 0 28.6 62.5 0 14.3 37.5 0 14.3 14.3 0 14.3 14.3 28.6 0 0 14.3 14.3 14.3 14.3 28.6 14.3 28.6 0 0 28.6 0 0 0 0 0 42.9 0 14.3 42.9 0 14.3 28.6 0 14.3 14.3 0 14.3 0 14.3 0 14.3 14.3 0 14.3 14.3 0 28.6 0 0 71.4 14.3

. 251 RECOGNITION RECOGNITION EXCLUSION New Words New N!Ws Aud. Words Aud. N/Ws New Words New N/Ws Aud. Words Aud. N!Ws 0 50 37.5 12.5 25 25 37.5 62.5 12.5 12.5 50 25 50 37.5 75 37.5 25 12.5 50 37.5 12.5 12.5 62.5 37.5 12.5 25 12.5 12.5 37.5 37.5 37.5 62.5 12.5 62.5 37.5 25 25 25 62.5 75 25 25 37.5 37.5 50 0 50 37.5 37.5 0 12.5 12.5 37.5 12.5 75 62.5 37.5 12.5 12.5 50 37.5 37.5 12.5 25 25 25 0 50 25 50 62.5 62.5 37.5 25 12.5 37.5 25 50 50 50 12.5 25 37.5 37.5 37.5 37.5 62.5 25 25 12.5 50 75 75 25 37.5 37.5 12.5 0 25 50 25 62.5 62.5 25 25 12.5 25 12.5 50 62.5 75 50 12.5 12.5 37.5 62.5 87.5 75 75 62.5 12.5 12.5 75 12.5 12.5 50 62.5 37.5 12.5 12.5 12.5 37.5 12.5 50 50 50 25 0 25 50 25 50 37.5 50 25 25 12.5 50 37.5 37.5 75 75 12.5 12.5 12.5 25 37.5 50 75 62.5 0 37.5 50 0 50 37.5 71.4 71.4 0 25 16.7 0 12.5 25 85.7 57.1 25 37.5 16.7 16.7 25 50 71.4 42.9 12.5 12.5 33.3 16.7 12.5 50 71.4 85.7 37.5 0 33.3 33.3 12.5 50 85.7 57.1 62.5 0 16.7 33.3 37.5 25 71.4 57.1 37.5 25 0 16.7 37.5 25 57.1 57.1 12.5 12.5 0 66.7 50 25 85.7 42.9 12.5 0 16.7 0 50 50 71.4 85.7 12.5 0 0 0 25 50 100 85.7 0 16.7 33.3 0 14.3 0 57.1 71.4 0 16.7 0 0 0 0 71.4 28.6 33.3 16.7 33.3 50 0 0 57.1 71.4 0 0 50 0 14.3 14.3 71.4 42.9 0 0 16.7 16.7 0 14.3 100 71.4 16.7 0 0 0 14.3 14.3 100 57.1 16.7 50 16.7 0 14.3 14.3 71.4 71.4 16.7 16.7 16.7 0 14.3 0 85.7 42.9 33.3 16.7 0 16.7 14.3 0 85.7 100 16.7 16.7 0 16.7 0 0 57.1 57.1 0 0 0 14.3 0 33.3 14.3 28.6 0 0 0 14.3 0 16.7 28.6 0 33.3 16.7 0 14.3 16.7 0 14.3 0 0 0 14.3 14.3 0 16.7 0 14.3 33.3 16.7 0 0 0 50 28.6 28.6 33.3 0 0 0 0 16.7 14.3 0 0 0 14.3 28.6 0 16.7 14.3 14.3 0 0 0 14.3 66.7 33.3 14.3 0 50 50 0 14.3 0 33.3 0 0 16.7 16.7 14.3 0 16.7 16.7 0 0

252 ANALYSIS OF VARIANCE TABLE: Experiment 6. Recognition.

Source SumSQ df MeanSQ F

Frequency 2256.250 1.000 2256.250 5.689 Lexicality. 4059.005 1.000 4059.005 10.235 Present. 1447.687 1.000 1447.687 3.650 Resp Ov1 40472.789 1.000 40472.789 102.051 Resp. 1v2 126.961 1.000 126.961 0.320 FreqXPres 104.167 1.000 104.167 0.263 FreqXRespO 1 170.666 1.000 170.666 0.430 FreqXresp12 2050.134 1.000 2050.134 5.169 LexXPres 422.454 1.000 422.454 1.065 LexXresp01 966.608 1.000 966.608 2.437 LexXResp12 183.750 1.000 183.750 0.463

ERROR 151102.359375 381.000 396.594

ANALYSIS OF VARIANCE TABLE: Recognition Exclusion.

Source SumSQ df MeanSQ F

Frequency 81.000 1.000 81.000 0.245

Lexicality. 132.845 1.000 132.845 0.402 Present. 45.387 1.000 45.387 0.137 Resp Ov1 406.272 1.000 406.272 1.231 Resp. 1v2 69.360 1.000 69.360 0.210 FreqXPres 1441.500 1.000 1441.500 4.366 FreqXRespO 1 0.375 1.000 0.375 0.001 FreqXresp12 594.075 1.000 594.075 1.799 LexXPres 56.767 1.000 56.767 0.172 LexXresp01 3.967 1.000 3.967 0.012 LexXResp12 23.438 1.000 23.438 0.071

ERROR 125780.84375 381.000 330.133

253 ANALYSIS OF VARIANCE TABLE: "Recollection" Estimates. Experiment 6

Source SumSQ df MeanSQ F Frequency 1398.759 1.000 1398.759 1.870 Lexicality. 5565.125 1.000 5565.125 7.439 Present. 1999.200 1.000 1999.200 2.672 Resp Ov1 48714.633 1.000 48714.633 65.120 Resp. 1v2 10.667 1.000 10.667 0.014 FreqXPres 2289.307 1.000 2289.307 3.060 FreqXResp01 138.240 1.000 138.240 0.185 FreqXresp12 4876.876 1.000 4876.876 6.519 LexXPres 776.021 1.000 776.021 1.037 LexXresp01 858.521 1.000 858.521 1.148 LexXResp12 67.204 1.000 67.204 0.090

ERROR 285017.9375 381.0 748.079

ANALYSIS OF VARIANCE TABLE: "Familiarity" Estimates.

Source SumSQ df MeanSQ F

Frequency 3010.539 1.000 3010.539 10.250

Lexicality 666.921 1.000 666.921 2.271

Present. 1264.702 1.000 1264.702 4.306

Resp Ov1 3873.936 1.000 3873.936 13.189 Resp. 1v2 181.335 1.000 181.335 0.617 FreqXPres 2796.124 1.000 2796.124 9.520 FreqXRespO 1 900.133 1.000 900.133 3.065 FreqXrespl2 99.969 1.000 99.969 0.340 LexXPres 348.765 1.000 348.765 1.187 LexXresp01 919.961 1.000 919.961 3.132 LexXResp12 47.370 1.000 47.370 0.161

ERROR 111024.078125 378.000 293.714

254 ALLBOOK BINDERY

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