PLANNING AND THE SURVIVAL PROCESSING EFFECT: AN EXAMINATION OF THE PROXIMATE MECHANISMS

Leisha A. Colyn

A Dissertation

Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements for the degree of

DOCTOR OF PHILOSOPHY

May 2014

Committee:

Richard Anderson, Advisor

Cynthia Bertelsen Graduate Faculty Representative

Howard Casey Cromwell

Harold Rosenberg © 2014

Leisha Colyn

All Rights Reserved iii ABSTRACT

Richard Anderson, Advisor

In two experiments on incidental learning in memory, survival processing of highly related information (i.e., DRM lists) was compared to two contextually rich encoding scenarios that were equated on several important characteristics and to a pleasantness processing task. Free recall and recognition memory were measured. Results from Experiment 1 indicated that the survival processing effect on true recall existed but was driven by congruity effects. However, a planning effect on false recall existed. That is, the three planning processing tasks produced greater false recall than the pleasantness processing task. The recall results of experiment 2 failed to replicate the recall results from Experiment 1. Regarding the recognition tasks, no survival processing effect in hit rate existed independent of congruity effect, but Experiment 2 demonstrated that hit rate was also affected by the relatedness of the information in the recognition environment.

Experiment 2 replicated the planning effect on false alarm rate above the effect of congruity effect that was demonstrated in Experiment 1. The survival processing task did not produce a greater false alarm rate than other processing tasks in Experiment , but did in Experiment 2. Experiment 2 also demonstrated that false alarm rate was affected by the relatedness of the information in the recognition environment. A small survival processing effect on proportion of recognition items correctly categorized was found in

Experiment 1, but failed to replicate in Experiment 2. Experiment 2 replicated the finding that when controlling for congruity effects, participants in all groups found it similarly difficult to discriminate between target and lure words on the recognition task. Further, iv Experiment 2 demonstrated that all groups found it more difficult to discriminate when lures were highly related versus moderately and unrelated. This was qualified by the congruity effect, as well. Both experiments demonstrated that all processing tasks produced similar criterion values. However, Experiment 2 demonstrated that participants in all groups used a more liberal criterion when information in the recognition environment was highly related to the target information than when information in the recognition environment was moderately-related or unrelated. Notably, the measures of the decision characteristics in recognition memory did not indicate any differences between encoding processing tasks.

Keywords: adaptive memory; false memory; recall; recognition; survival processing; evolutionary theory v

Dedicated to WF, PJ, JM, and JY.

Thank you for your unconditional friendship and support.

vi ACKNOWLEDGMENTS

I would like to thank Richard Anderson for nudging me to explore cognitive psychology. I am grateful for the knowledge and experience gained in this area. I am grateful for his thoughtful advice and support throughout the years. I also appreciate the insight and expertise of my committee members Cynthia Bertelsen, Casey Cromwell, and

Harold Rosenberg. Finally, I am grateful for the variety of research-related support from

Alex Earl, Wendy Fogo, Peter Jaworski, Amanda Kelley, Jennifer McInroe, Jacob

Sparks, Zach Walworth, and Jennifer Yugo. vii

TABLE OF CONTENTS Page

CHAPTER I: INTRODUCTION ...... 1

Memory Processes ...... 6

Taxonomy of Memory ...... 13

Long-term memory...... 14

Influences on long-term memory performance...... 15

Competing models of storage...... 15

Organization of long-term memory...... 16

Levels of processing...... 18

Additional related encoding and retrieval effects on long- term memory...... 21

Survival-processing effect...... 22

The evolution of cognitive biases: Error management theory. 31

Summary and Overview of Present Research ...... 32

CHAPTER II: EXPERIMENT 1 ...... 37

Method ...... 38

Participants...... 38

Materials and design...... 40

Stimuli...... 41

Rating task...... 41

Grasslands photo...... 42

Grasslands survival...... 42

Dinner party...... 42 viii

Distraction task...... 43

Recall task...... 43

Attention check...... 43

Recognition task...... 43

Ease of visualization and narrative descriptions...... 45

Procedure...... 45

Results ...... 47

Ease of visualization...... 47

Ratings...... 47

Recall...... 48

Correct recall...... 49

Intrusions...... 51

Recognition...... 53

Hit rate...... 54

False alarm rate...... 54

Proportion correct...... 54

d'...... 55

Criterion...... 56

Summary and Discussion ...... 56

Overview of Experiment 2 ...... 59

CHAPTER III: EXPERIMENT 2 ...... 61

Method ...... 62

Participants...... 62 ix

Materials and design...... 64

Stimuli...... 64

Control questions...... 64

Procedure...... 64

Results ...... 65

Ease of rating...... 65

Ease of visualization...... 65

Ratings...... 65

Recall...... 66

Correct recall...... 67

Intrusions...... 67

Recognition...... 68

Hit rate...... 68

False alarm rate...... 69

Proportion correct...... 70

d'...... 70

Criterion...... 71

Summary and Discussion ...... 72

CHAPTER IV: GENERAL DISCUSSION ...... 74

Possible Limitations ...... 80

REFERENCES ...... 83

APPENDIX A: RATINGS STIMULI ...... 94

APPENDIX B: RECOGNITION STIMULI ...... 97 x

APPENDIX C: NARRATIVE DESCRIPTIONS OF PROCESSING TASKS ...... 99

APPENDIX D: EXPERIMENT 1 HRSB-APPROVED CONSENT LETTER ...... 101

APPENDIX E: EXPERIMENT 2 HSRB-APPROVED CONSENT LETTER ...... 103 xi

LIST OF TABLES

Table Page

1 Established Influences on Memory Performance ...... 105

2 Experiment 1 Means and Standard Deviations of Recall and

Recognition Measures ...... 107

3 Experiment 2 Means and Standard Deviations of Recall and

Recognition Measures ...... 108 xii

LIST OF FIGURES

Figure

1 Experiment 1 mean relevance/pleasantness ratings ...... 110

2 Experiment 1 mean number of words correctly recalled ...... 111

3 Experiment 1 mean number of words falsely recalled ...... 112

4 Experiment 1 hit rate in recognition memory ...... 113

5 Experiment 1 false alarm rate in recognition memory ...... 114

6 Experiment 1 mean proportion of recognition Items correctly categorized ...... 115

7 Experiment 1 mean d' ...... 116

8 Experiment 1 mean criterion ...... 117

9 Experiment 2 mean relevance/pleasantness ratings ...... 118

10 Experiment 2 mean number of words correctly recalled ...... 119

11 Experiment 2 mean number of words falsely recalled ...... 120

12 Experiment 2 hit rate in recognition memory ...... 121

13 Experiment 2 false alarm rate in recognition memory ...... 122

14 Experiment 2 mean proportion of recognition items correctly categorized ...... 123

15 Experiment 2 mean d' ...... 124

16 Experiment 2 mean criterion ...... 125 PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 1

CHAPTER I: INTRODUCTION

Memory plays an important role in everyday life, enabling the storage and retrieval of information about prior experiences. People rely on memory to get through the day in a variety of ways: to walk, to drive, to multi-task, to make decisions. Long-term memory is essential to basic cognitive functions, allowing people to interact with objects in their environment by storing information about what those objects are and about successful or unsuccessful interactions with those objects in the past. If long-term memory is successful, for example, people do not have to rediscover what a toothbrush is each morning.

Long-term memory is inherently oriented toward the future. That is, memory processes extract from the environment information that will be useful in future situations (Klein,

Robertson, & Delton, 2010; 2011). Long-term memory is considered to be adaptive in the sense that new information can be used to update existing knowledge. People also use the information from long-term memory to behave more adaptively. For example, someone going on a camping trip for a second or third time has presumably created long-term memories about the trip that will serve as the basis for planning what to pack and how to behave on the upcoming trip.

Several factors affect long-term memory performance, including organization, distinctiveness, novelty, emotional valence and arousal, planning, and information processing instructions. The present research examines a particularly beneficial effect on long-term memory known as the survival-processing effect--i.e., the benefit, in memory performance, from processing information in a survival-relevant context (Nairne, Thompson, & Pandeirada, 2007).

The theoretical basis of the survival-processing effect is rooted solidly in biology and evolutionary psychology. Evolutionary psychologists apply the theory of evolution to psychological phenomena, including cognitive processes such as memory. Evolutionary-based PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 2 accounts contend that current cognitive processes result from the evolutionary process of natural selection (e.g., Klein, Cosmides, Tooby, & Chance, 2002; Todd, Hertwig, & Hoffrage, 2005).

Darwin (1859) described natural selection as a process whereby heritable physical and psychological characteristics that aid in an organism’s survival become more numerous in the population over time. Among other cognitive processes, memory may have evolved to its current state because some individuals possessed heritable characteristics that facilitated successful solutions to survival-related problems (Klein, Cosmides, Tooby, & Chance, 2002; Nairne,

Thompson, & Pandeirada, 2007, Todd, Hertwig, & Hoffrage, 2005). With regard to memory, the assumption is that some individuals had heritable characteristics that facilitated the storage and recall of survival-relevant information, thus enhancing the chances of those characteristics being passed to subsequent generations.

Imagine, for example, that Jake and Bob are on a camping trip. Jake has the ability to store and retrieve a memory that a dark red berry he ate during his hike induced extreme illness.

Bob does not possess this ability. When the men repeatedly encounter the dark red berry, Jake’s ability to retrieve the memory of his prior experience eating the berry enables him to use the information when deciding if he should eat the berry. Jake is likely to avoid extreme illness by avoiding the dark red berry; however, Bob cannot rely on stored information to guide his decisions and behaviors. Without prior information to warn him away from the berry, Bob is certain to eat the dark red berry when hungry (if he even knows that a dark red berry will end his hunger). Thus, Jake benefits from the ability to store and retrieve memories about experiences.

Memory allows Jake to avoid illness, thereby increasing the probability that he will live long enough to reproduce and pass on the heritable characteristic(s) involved in the memory process, whereas Bob will be less likely to survive to pass on the heritable characteristic(s) associated PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 3 with the lack of memory ability. For a more vivid example, consider the consequences if Bob lacked the ability to remember which moving beasts tried to eat him. The case of Jake and Bob demonstrates the process known as selection.

Environmental factors can promote selection of particular traits, such as memory ability in Jake’s case. These factors, known as selective pressures, include environmental threats such as predators or tsunamis, as well as limits on resources necessary for survival and procreation. A common approach in evolutionary psychology involves hypothesizing about the characteristics of a psychological mechanism given the selection pressures that likely shaped the mechanism. In other words, evolutionary cognitive psychologists hypothesize about what memory would look like today given likely selection pressures existing during a species’ environment of evolutionary adaptation. If memory evolved in response to these types of selective pressures, then current memory systems should reflect “sensitivities” to this type of information and should perform optimally under conditions that mimic the selective pressures (Nairne, Thompson, & Pandeirada,

2007; Klein, Cosmides, Tooby, & Chance, 2002).

Accordingly, Nairne and colleagues (e.g., Nairne, Thompson, & Pandeirada, 2007;

Nairne, Pandeirada, & Thompson, 2008; Nairne & Pandeirada, 2010; 2011) predicted that information processed in a survival-relevant context would be remembered better than information processed in survival-non-relevant contexts. The survival-relevant context involves selective pressures such as avoiding predators and finding food. Specifically, a survival-related scenario describes a situation where participants are stranded in the grasslands of a foreign nation and must survive by finding food and avoiding predators. Survival-non-relevant contexts include contextually rich scenarios that do not involve selective pressures (e.g., moving to a foreign land), and conditions that demonstrate robust benefits to memory (e.g., self-reference processing- PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 4

-considering how easily words bring to mind a memory of oneself). Some research supports

Nairne’s predictions. Memory performance often benefits more from survival processing than from other factors.

Numerous subsequent studies have examined a variety of potential proximate explanations for the survival-processing effect. Congruity effects, or the tendency for people to remember information better if it is congruent to the way in which it was processed (Schulman,

1974), have been identified as contributing to the survival-processing effect. The survival- processing effect is often accompanied by better memory for words rated as more relevant, to the survival scenario than for words rated less relevant (e.g., Nairne & Pandeirada, 2011).

Contextually rich encoding procedures have also been posited as a proximate explanation for the memory benefit of survival processing. The scenarios employed to induce survival processing are contextually rich and vivid in nature. The control groups used often do not match the survival scenario in richness. For example, comparing survival processing to a task where one rates the pleasantness of a word often produces the survival processing effect (e.g., Nairne,

Thompson & Pandeirada, 2007; Nairne, Pandeirada, & Thompson, 2008; Nairne & Pandeirada,

2008; Kang, McDermott, & Cohen, 2008). That is, the correct memory performance is better after survival processing than pleasantness processing. However, the pleasantness-processing task contains much less contextually rich information than the survival scenario. Similarly, the novelty or distinctiveness of the survival scenario might explain the benefit to memory.

Researchers have also identified the combination of distinctiveness and relational processing as the proximate explanation for the survival-processing effect. Distinctiveness has been described as the processing of item-specific information, whereas relational processing has been described as the processing of similarities of information in the environment during PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 5 encoding. Evidence suggests that engaging in a combination of relational and item-specific processing produces a superior effect than either alone (Einstein & Hunt, 1980; Hunt & Einstein,

1981; Hunt & McDaniel, 1993). Relational processing is said to act as an organizing structure for retrieval, whereas item-specific processing aids discrimination of individual items within the organizing structure (Burns, Burns, & Hwang, 2011).

A recently proposed explanation for the survival-processing effect is planning. Planning for the future is a primary function of memory. Processes tend to operate more effectively when performing functions for which they adapted, than when performing functions for which they are not adapted. Thus, if the memory process is used to plan for future events, then it should operate more effectively, than when it is used without planning for the future. Evidence provided by

Klein and colleagues (Klein, Robertson, & Delton. 2010; 2011) supports this thesis. Survival scenarios producing the survival-processing effect often include a planning for the future planning-for-the-future component that control groups do not (e.g., pleasantness rating; Klein,

Robertson, & Delton, 2011).

In the following sections, I present a more detailed discussion of memory and related processes. I also describe each of the potential explanations for the survival-processing effect, and provide an overview of the present research.

PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 6

Memory Processes

Memory is the process of encoding, storing, and retrieving information. Memory operates interdependently with learning and decision processes (Klein, Cosmides, Tooby, & Chance,

2002). One cannot have memory without the process of learning, which is the acquisition of the information that is stored in, and retrieved from memory. Learning also updates knowledge stored in memory by modifying the existing information to incorporate newly acquired information. The learning process also involves encoding of perceptual information from the environment, such as visual images.

Encoding plays an essential role in forming and storing new memories. The encoding process involves converting perceived physical stimuli (light, for example) into a usable mental construct that can be stored by the brain for later retrieval. Several types of encoding exist corresponding to each of the senses. For example, visual encoding involves transforming light waves into visual images that are temporarily stored in the visuo-spatial sketchpad, which is a component of the working memory system that is limited in storage capacity and duration

(Baddeley, 1990; Baddeley, Eysenck, & Anderson, 2009; Sperling, 1960).

Once encoding occurs, the mental construct can potentially be manipulated in working memory, connected with existing concepts, transferred to, stored in, and retrieved from long- term memory. The storing of information refers merely to the retention of that information.

Retrieval of information involves an information search in memory and several decision processes. In research, and often in everyday life, some behavioral response--e.g., circling the correct answer on a multiple choice recognition test--indicates the outcome of the retrieval process.

Retrieval should not be viewed as digging through a file drawer for an old file that was PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 7 previously stored there. Rather, memory retrieval should be viewed as an imperfect reconstruction process that involves decision sub-processes. People must make decisions about whether the information activated during the search stage matches the sought information; one can say that this decision is made under conditions of uncertainty. In fact, the observation that most people do not always perform perfectly on retrieval tasks supports the contention that decisions regarding memory are made under conditions of uncertainty. Researchers examining the survival-processing effect rarely consider particular characteristics of the decision process.

More specifically, a gap in the survival-processing literature exists with regard to bias in decision-making.

Memory processes involve a search sub-process as part of the larger retrieval process. It is a grand task, indeed, to search memory and identify concepts (or more complex information) based on a certain criteria, e.g., the recency of concept activation or familiarity. Once candidate concepts are identified from the memory search, one must engage in a decision process. That is, one must compare some characteristic of the activated concepts to a criterion for confirmation or rejection of the concept as the target concept that is sought.

Various factors can impact the decision sub-process during a retrieval task. Motivation, strategy, and goals can all influence decision processes. For example, paying people to recognize as many words from the previously presented word list as possible might encourage “yes” answers to every word on the recognition test such that people maximize their rewards. Thus, the criterion value for saying yes may be decreased, allowing both more errors and correct responses. As another example, someone who recently pondered surviving in the wilderness, or who is walking in the wilderness, might be more likely to judge a stick to be a snake. According to Error Management Theory (EMT; Haselton & Buss, 2000), cognitive biases such as this likely PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 8

evolved and currently serve to reduce costs of missing a potentially serious threat.

Two types of retrieval tasks used in research, explicit and implicit, inform us about different characteristics of memory. Each memory task provides unique insights into memory: In explicit retrieval tasks, researchers direct participants to try to remember information, whereas in implicit tasks, researchers direct participants to complete a learning task ostensibly unrelated to memory evaluation (Roediger, Weldon, & Challis, 1989). In the typical word-list memory experiment (e.g. Peterson, 1966), participants learn a word list either incidentally or intentionally and then perform an unrelated task for a period of time. (This period of time is known as the retention interval.) Participants then complete either a recall test, a recognition test, both.

In a recall test, participants generate the previously learned items on their own (Bartlett,

1932). For example, participants may be asked to report all the words they remember seeing during the first part of the study (i.e., the encoding/learning phase). Several kinds of recall tasks exist. In cued recall tasks (Tulving & Pearlstone, 1966), researchers present participants with a cue that appeared with the stimuli during the encoding phase. Participants then attempt to generate the target stimuli associated with that specific cue. In serial recall tasks, participants are required to generate the previously encoded information in the same order they learned it, whereas in free recall tasks participants can recall the information in any order (Waugh, 1961).

In a recognition test, participants view a list of words provided by the experimenters and identify previously learned words. Two primary recognition tasks include forced-choice and yes/no tasks. Forced-choice recognition tasks require participants to choose which of two words, one old and one new, was previously presented (Macmillan & Creelman, 2005). This method is sometimes referred to as mAFC, where m can be any number indicating the number of options participants choose from and AFC means “alternative forced-choice.” PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 9

During this recognition task, choosing which word was previously viewed (i.e., recognition), presumably involves participants thinking in their minds about which words are more familiar and then reporting those more familiar words to the experimenter. Thus, people generate some value of familiarity for each word, compare the values of all words, and report the word with the greatest value (Stanislaw & Todorov, 1999).

Yes/no (sometimes called “old/new”) recognition tasks require participants to make a yes/no (old/new) decision about a list of words. That is, during this recognition task, participants view a list of words that contains the words previously presented and new words (“lures”). For each word on the recognition test, participants consider whether or not the word was previously presented. Presumably participants assess the familiarity of the word and compare the value of familiarity to a subjective internal criterion. If the familiarity of the word on the recognition test exceeds the internal criterion, participants respond “yes” or “old.” Otherwise the participants respond “no” or “new.” (However, as previously mentioned, participants might also engage in strategies that serve to enhance their chances of achieving a certain outcome.) Participants completing a yes/no task make a decision about each word on its own, comparing the familiarity of each word to an internal criterion.

In a yes/no task, individuals can identify a word as old when it is, in fact, old. This is known as a hit (Green & Swets, 1966). An individual can also identify a word as new when it, in fact, is new (or “correct rejection”). Two errors are possible. Type I error refers to incorrectly identifying a word as old when it was not previously presented ("false alarm," otherwise known as “false positive”). Type II error refers to failing to identify a word as old when it was previously presented (“miss” or “false negative”). Each error involves costs to the observer. For example, an individual may set a high criterion for indicating that they previously saw a word in PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 10 order to reduce the number of false alarms, but in doing so produces fewer hits than if the individual were to set a lower criterion. Increasing the threshold for signals inherently increases the probability of committing a Type II error. However, when an individual lowers the criterion for detecting signals, a greater number of false alarms tend to accompany the increased number of correctly identified signals. Alternatively, if one attempts to control for type II error through a more liberal criterion, the probability of committing a type I error increases. This represents a bias in detecting stimuli.

Recall and recognition tasks each result in different memory performance. Recognition tasks often produce better retrieval results than do recall tasks, presumably because recall is more difficult (Haist, Shimamura, & Squire, 1992) and seems to be sensitive to particular types of encoding instructions (e.g., item-specific processing). Cued recall results in better memory performance than free recall (Baddeley, 1990), and the best retrieval cue for a piece of information is that piece of information itself. Because recognition relies on information seeming familiar, information that cannot be accessed through recall can still be retrieved using recognition.

Several models of recognition memory exist, but the current research focuses on the false memory model suggested by Roediger and McDermott (1995) and made explicit by Stretch and

Wixted (2000). This model of recognition memory assumes that all stimuli have some prior strength of memory trace (Wixted, 2007). Generally the memory trace is conceptualized as familiarity, but might better be conceptualized as strength of evidence per Wixted and Stretch

(2000). The strength of evidence “represents the degree to which one remembers having recently encountered an item” (Wixted & Stretch, 2000). In the case of a typical memory experiment, for example, when words are presented to participants, the strength of the evidence (Si) for those PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 11 words increases. This increase in strength of evidence occurs for items presented in the study, but not for items not presented. The increase in strength due to presentation of a stimulus can be symbolized by (Pi). Additionally, strength of evidence can be indirectly influenced by associative activation (Ai) from other presented words (Wixted & Stretch, 2000). Thus, the current research employs the simple model:

Si = Pi + Ai where Si = strength of evidence i, Pi = strength from presentation, and Ai = strength from associative activation.

Wixted and Stretch (2000) argue that the increased rate of false memory in Roediger and

McDermott’s (1995) study occurs for related words because the strength of evidence for related words was increased by activation of associated words. This explains why related lures were falsely identified at higher rates than unrelated lures. An alternative explanation for increased false memory appeals to a shift in the criterion in the memory decision process. If the criterion became more liberal, then the number of false memories would increase along with the number of true memories.

Roediger and McDermott (1999) contend that their model of false memory better fits the data than a criterion-shift theory proposed by Miller and Wolford (1999). Wickens and Hirshman

(2000) and Wixted and Stretch (2000) also support Roediger and McDermott’s model of false memory as better than the criterion-shift theory in explaining their data. These researchers demonstrate that a shift in observed criterion could be caused by either a real criterion shift by the participant or a shift in the signal and/or noise distributions. That is, the mean strength of evidence for critical lures differs from the mean strength of evidence for the related lures, which differs from the mean strength of evidence for the unrelated lures. The current research will PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 12 examine these effects in survival-processing using signal detection measures of accuracy and bias

Sensitivity, or discriminability, could be described as how accurate someone is in classifying a stimulus as either signal (i.e., target word that was previously presented) or noise

(i.e., lure word that was not previously presented). Discriminability can be considered a type of accuracy and is most commonly assessed in the signal detection paradigm using d-prime (d').

d' = z(HR) - z(FA), where z(HR) refers to the standardized z-score for the hit rate and z(FA) refers to the standardized z-score for the false alarm rate.

The use of d’ requires that two underlying assumptions be met in order for d' to be a useful measure of discriminability independent of response bias. First, the separate distributions for old words and new words must be normally distributed. Second, the standard deviations of the distributions must be equal. Additionally, the basic assumptions underlying d' are the same basic assumptions of commonly used statistical inference tests, such as analysis of variance.

Researchers tend to accept these assumptions readily. These assumptions can be easily tested in analyses of variance, but require fitting the data to an ideal model when using signal detection theory (Pastore, Crawley, Berens, & Skelly, 2003).

Measuring bias in recognition tasks can be done using c, which is a measure that is unaffected by discriminability, unless the assumptions of the model have not been met. c refers to the distance from the criterion for responding yes or no to the neutral point.

c = - [z(HR) + z(FA)] / 2

The neutral point is where the distributions for old words and new words cross and there is no response favored. At the neutral point, c = 0. A criterion on either side of the neutral point PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 13 indicates a bias; placement to the left of the neutral point indicates a liberal criterion--and a liberal bias, and placement to the right of the neutral point indicates a conservative criterion--and a conservative bias. These deviations from the neutral point are measured in standard deviations

(Stanislaw & Todorov, 1999).

Taxonomy of Memory

Memory is multifaceted and complex, but that has not stopped psychologists from attempting to model its processes. These models have changed over time, from very basic two- component models (e.g., primary and secondary memory) to three and five-component models

(see Klein, Cosmides, Tooby, & Chance, 2002). Short-term memory, an older concept, refers to the memory component that holds a limited amount of information for about 30 seconds.

Working memory, a more recent concept in the study of memory, is similar to short-term memory but involves the mechanisms and processes for manipulating a limited amount of information for a short period of time (see Baddeley, 1990, 2012 for an extensive discussion).

Working memory can be further divided into four main components: the central executive

(responsible for initiating the cognitive processes involved in information processing), the phonological loop (consisting of the phonological store and articulatory loop and functioning as a way to rehearse information and hold it in temporary memory), the visuo-spatial sketchpad

(responsible for processing and holding visual information), and the episodic buffer (responsible for binding information from different parts of memory into a long-term memory).

Limitations of time and mental resources especially affect short-term and working memory. Both short-term and working memory operate separately from, but in coordination with, the long-term memory component. Repetition and elaboration of information in short-term and working memory results in a transfer of information to long-term memory, where it might PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 14 later be retrieved (Atkinson & Shiffrin, 1968; Craik & Tulving, 1975). If information is not transferred to long-term memory, it will be forgotten fairly quickly once rehearsal ceases. The present paper focuses on the effects of a particular long-term memory encoding technique on long-term memory performance.

Long-term memory. Long-term memory can be divided into two main categories: declarative (explicit) and non-declarative (implicit, or procedural) memory. Explicit memory includes knowledge about facts (semantic memory) and events (episodic memory) that can be consciously retrieved and reflected on. In contrast, implicit memory includes knowledge that does not require conscious processes. Implicit memory includes skills and habits, priming, simple classical conditioning, and nonassociative learning (Squire, 1993). Remembering how to walk, ride a bicycle, read, or play a piano each involve implicit processing. While explicit knowledge is also necessary for some of these tasks, the basic processes involved use implicit memory.

A common priming effect can help elucidate the nature of implicit memory. The repetition priming effect refers to the phenomenon of reading a word faster after having previously been exposed to the word (Masson, 1984). When readers reach the twentieth page of the present paper, not only will they be contemplating facts and relationships between these facts

(i.e., semantic knowledge), but they will also be reading many of the words much faster, having been exposed to several words numerous times throughout the paper. Implicit memory enables people to operate some basic and common processes automatically and efficiently, which frees up cognitive resources that can then be applied to more complex or difficult behaviors.

Memory is susceptible, suggestible, and malleable, and it constantly incorporates new information into existing knowledge. Several factors can influence memory; some--like the PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 15 repetition priming effect mentioned above--improve memory performance, whereas others diminish memory performance. Errors in long-term memory impact our daily lives. Imagine misremembering the leftovers in the refrigerator as being only two days old rather than two weeks old.

Numerous factors influence whether memory works well, including certain characteristics of the information being processed. Emotional arousal and emotional valence, for example, both influence memory. The following section provides a brief overview of several well-established influences on the memory process that impact memory performance.

Influences on long-term memory performance. Successful storage in long-term memory depends on numerous variables. Repetition or rehearsal, organization of information, imagery, and semantic, relational, and item-specific processing each improve memory performance and inform us about how the mind stores information. (See Table 1 for a brief description of established influences on memory performance). A discussion of the influential factors pertinent to the current research follows.

Competing models of storage. Two primary approaches attempt to explain optimal memory performance by appealing to relational and item-specific processing. Recall that in the former, information about discrete events is encoded with respect to its similarity to other discrete events occurring within the same context (Hunt & Einstein, 1981). The latter involves encoding information specific to each event. The organizational framework holds that relational processing results in optimal memory performance, whereas the levels-of-processing approach predicts that item-specific processing results in optimal memory. However, subsequent research demonstrates that a combination of the two types of processing results in optimal memory performance. Each approach will be discussed in turn. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 16

Organization of long-term memory. Long-term memory is highly organized. Bousfield

(1953) presented participants with a series of words, each drawn from one of several different categories. The words were show in a random order, but participants spontaneously recalled the words in groups reflecting the categories. Additionally, when no salient category existed between numerous words, participants subjectively organized the words during recall. Participants made up their own way to associate the words and used that method to recall the words. This indicates that information was stored in an organized fashion, allowing for retrieval in the same manner.

Subsequent research on the organizational structure of memory demonstrated that organization of information is not restricted to categorical or hierarchical structure. Rather, memory seems to be organized in an associative manner. The connectionist model of memory demonstrates this idea.

The connectionist model of memory proposes that concepts can be represented by nodes in a network, connected to other concepts with directional pathways. Each concept contains properties and the pathways represent information about relationships between connected concepts. When a concept is activated, a spreading activation of related concepts occurs, beginning with the most strongly associated (Collins & Quillian, 1969; Collins and Loftus,

1975). For example, the concept of sleep is strongly associated with the concept of bed. When presented with the concept “sleep,” the concept “bed” is strongly activated. Thus, “bed” will likely come to mind. Alternatively, to continue with the sleep example, concepts not strongly associated with “sleep” (e.g., banana) will not be activated and will likely not come to mind.

Additionally, spreading activation of concepts tends to weaken as psychological distance from the concept increases and associations with the original concept are much weaker.

Relational processing can be considered a type of elaboration (e.g., Meyers-Levy, 1991) PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 17 where information about the similarity of one element in a particular context is extended to other elements within that context, creating strong associations between concepts with similar elements that will aid in retrieval. More specifically, relational information has been theorized to restrict the search strategy by creating an organizational structure to aid in retrieval (Burns,

2006). Processing relational information differentially improves memory; memory improves more in some cases than in others (Hunt & Einstein, 1981). Additionally, relational processing produces more false memories (Deese, 1959; Roediger & McDermott, 1995).

Hunt and Einstein (1981) demonstrated that the type of materials impacts the success of the encoding strategy. Specifically, relational processing improves memory more for ostensibly unrelated pieces of information than for already related information. Additionally, relational processing produces superior memory performance in recall tasks relative to recognition tasks

(Einstein & Hunt, 1980). One drawback to relational processing involves the increase in false memory (Roediger, & McDermott, 1995). The semantic relatedness effect refers to the tendency for highly related words to be retrieved and judged faster than unrelated words (Collins &

Loftus, 1975). Semantic relatedness, or strength of the association of concepts, can impact memory performance with respect to overall accuracy as well. For example, many studies have demonstrated that strongly associated information produces more false memories (e.g., Hunt &

Einstein, 1981; for a review see Roediger & McDermott, 2000).

This organizational tendency relates to the concept of schemata, defined as overarching cognitive structures of knowledge. People acquire schemata through experience and use them to aid in organizing and retrieving information from memory and understanding events and behaviors (Bower, 2000). In a seminal experiment, Bartlett (1932) asked people to read a Native

American story called the “War of the Ghosts.” When his participants later recalled the story, PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 18 they tended to misremember the details of the story as being more similar to their cultural expectations than was true of the original story, which contained details relevant to Native

American cultures. Previously established schemata may also be used to improve memory

(Roediger & McDermott, 1995). Retention of new information is better when it is congruent than when it is incongruent with one’s schema, especially when recall (rather than recognition) tasks are used (Alba & Hasher, 1983; see Pichert & Anderson, 1977).

A related ameliorative effect, the self-reference effect, occurs when people think about information with regard to themselves. The self acts as an organized structure of information about the world that facilitates elaboration and organization of new information that is related to oneself (see Klein, 2012, for a review). In fact, the self has been referred to as somewhat of a

“super schema.” Some researchers have suggested that because people are so skilled in thinking about the self, they can engage in greater item-specific processing of information related to the self (Kihlstrom, 1993). However, Klein and Loftus (1988) showed that the self-reference effect relies on a combination of relational and item-specific processing. The combination of encoding procedures results in better memory performance than each alone. Accordingly, thinking about information in terms of how it relates to oneself is one of the strongest mnemonics in memory research (Klein, 2012; also see Symons & Johnson, 1997, for a meta-analytic review).

Levels of processing. The levels-of-processing framework represents the other primary view on optimal memory performance. This framework focuses on the degree to which information is elaborated upon during the encoding phase. The levels-of-processing framework

(Craik & Tulving, 1975) posits that information can be encoded at different levels: deep and shallow. Information processed incidentally, or unintentionally, is processed at a shallow level and not elaborated upon. This information is merely kept in memory through maintenance PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 19 rehearsal. In contrast, information that receives direct attention is elaborated upon during elaborative rehearsal.

Similar to the organizational approach, the levels-of-processing approach allows numerous semantic connections to be made, but with regard to item-specific information rather than similarity, resulting in a “deeper” level of processing (i.e., semantic processing).

Researchers came to settle on distinctiveness as the dimension that drives item-specific processing. That is, distinctive information is abstracted and elaborated upon. An illustration of this might be the von Restorff effect, which refers to improved recall for information that is different in some obvious way from others (Hunt, 1995). Red ink would most certainly stand out against the black type of this paper, making it more likely that any message written in red ink on this paper will be remembered better than other messages written in black throughout.

The greater the number of semantic associations made during elaboration, the more likely it is that information can be retrieved later. Thus, memory should be better for processing tasks eliciting elaborative rehearsal than those eliciting maintenance rehearsal. Craik and Tulving

(1975) found that thinking about the meaning of a stimulus (i.e., semantic/deep processing) results in better memory than processing just the sounds of the words (i.e., phonologically, presumably shallow processing). They suggest that the former created a more durable memory trace than the latter. However, Glenberg, Smith, and Green (1977) found that maintenance rehearsal alone improved memory. A major criticism of the levels-of-processing framework contends that there is no way to independently define the type of rehearsal without appealing to memory performance, rendering the argument circular (see Baddeley, 1978).

However, the focus on elaborating on item-specific or distinctive characteristics of information remains quite relevant. Item-specific processing improves memory. For example, the PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 20 emotional content of information is item-specific. People tend to remember emotionally-laden information better than non-emotional information. Both emotional valence, an item’s subjective emotional value (negative to positive) and emotional arousal, an item’s subjective intensity (low to high) improve memory (Grider & Malmberg, 2008; Hamann, Cahill, & Squire, 1997; see

Hamann, 2001, for a review). Memory is more accurate for stimuli of high valence and high arousal (Grider & Malmberg, 2008). Higher emotional arousal leads to narrower focus

(Kensinger, 2009). In fact, narrowed focusing tends to occur more often for negative information than for positive information (Kensinger, 2009).

The evidence regarding the influence of emotional valence on memory performance in recognition studies is somewhat mixed. Some studies have found that people recognize negative stimuli better than neutral stimuli (Comblain, D’Argembeau, Van der Linden, & Aldenhoff,

2004; Hamann, 2001; Kensinger & Corkin, 2003; Ochsner, 2000; Pesta, Murphy, & Sanders,

2001; for decreased accuracy of negative stimuli, see Danion, Kauffmann-Muller, Grange,

Zimmerman, & Greth, 1995; Dougal & Rotello, 2007; Maratos, Allan, & Rugg, 2000) and others have found no difference in recognition accuracy for negative and neutral stimuli (Doerksen &

Shimamura, 2001; Ochsner, 2000).

Other item-specific influences include serial-position effects. Stimuli that appear earlier and later in experiments are better remembered than stimuli presented in the middle of the experiments. In the case of the former, the primacy effect, research suggests that the information has been sufficiently rehearsed and transferred into long-term memory, enhancing retrieval of those items later. The latter case, the recency effect, probably occurs because these stimuli are still active in working memory when participants are asked to recall the information (Rundus,

1971; Rundus & Atkinson, 1970). PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 21

Additional related encoding and retrieval effects on long-term memory. Contextual factors, including a person’s environment and psychological states during encoding, storage, and retrieval, impact memory performance. For example, one study found that people's memories are more accurate when they are feeling sad than when they are feeling happy. Happiness results in greater false recall (Storbeck & Clore, 2005). Along these lines, mood congruent learning

(Bower, 1981), refers to the consistent effect that learning is better when information is recalled in the same mood as when learned.

More generally, the encoding specificity principle (Tulving & Thomson, 1973) holds that information is encoded into a rich memory representation that includes the context during the encoding process. A famous experiment by Godden and Baddeley (1975) demonstrated this encoding specificity effect. Two groups of participants learned a list of words. One group of participants was on land when they learned the words and the other group of participants was under water when they learned the words. Participants were asked to recall the words in either a congruent or incongruent context. Memory performance was better for participants who learned and recalled the words in the same context than for those who learned and recalled in different contexts. That is, of participants who learned words while on land, those who recalled words on while land had greater recall than those who recalled words while under water.

Congruence can influence memory in other ways, as well. The congruity effect refers to better memory when the encoding task uses orienting questions that elicit a “yes” rather than

“no” response (Schulman, 1974). A participant’s response to orienting questions about the stimuli has been shown to differentially affect subsequent memory performance. For example, during the encoding phase of their classic levels-of-processing experiment, Craik and Tulving

(1975) asked participants orienting questions about the stimuli. Participants could respond with a PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 22

“yes” or “no.” Results showed that participants could better recall words that they had previously answered “yes” to an orienting question than words to which they had previously answered “no” to, consistent with the congruity effect.

Planning for the future has also been demonstrated to improve memory performance.

Klein, Robertson, and Delton (2010) contend that planning for the future is a necessary component of human cognitive architecture and that it works interdependently with memory systems. Information from memory processes is used to make decisions about current and future events. Long-term memory processes allow people to use information from previous experiences to make decisions and plan about current or future behavior. Human cognitive architecture is sufficiently complex and flexible to allow people to create innumerable hypothetical future events. That is, people are able to bring to mind information stored in memory, integrate that information with other information, and create novel hypothetical situations. Based on information about prior experiences with similar characteristics, people can make probability estimates about the likelihood of particular outcomes, which then presumably guide behavior. In order for someone to be able to behave more adaptively, the cognitive architecture that enables access to information stored in long term memory, decision processes that facilitate discriminative selection of relevant information, and processes that use the information to plan behavior must exist. In fact, Klein and colleagues (Klein, Robertson, and Delton, 2010; 2011) demonstrated that planning does improve memory performance.

Survival-processing effect. A final noteworthy influence on long-term memory performance, and the influence under investigation in the present study, involves encoding information within a fitness-relevant context. Survival processing aids memory performance whether the encoding is incidental or intentional (Howe & Derbish, 2010; Nairne, Pandeirada, & PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 23

Thompson, 2008; Weinstein, Bugg, & Roediger, 2008). Interestingly, information that is inherently survival-related is sometimes remembered better than information that is not inherently survival-related, though this is not always the case (e.g., Howe & Derbish, 2010). This beneficial memory effect occurs when assessing memory with both recall and recognition tasks.

Though the number of words correctly recalled in a memory test is usually the dependent variable in this research, some researchers also include false recall, or “intrusions” in memory, in determining the effect of survival-processing (e.g., Nairne & Pandeirada, 2008). A few studies

(e.g., Kang, McDermott, & Cohen, 2008; Nairne, Thompson, & Pandeirada, 2008) examine recognition memory and account for false alarms (i.e., words falsely recognized).

The survival-processing effect has been demonstrated to be stronger than other beneficial memory effects resulting from an array of semantic processing tasks. For example, better memory performance occurred when processing words in a fitness-relevant context than processing words using a generation task (Nairne, Pandeirada, & Thompson, 2008), a self- referential processing task (Nairne, Pandeirada, & Thompson, 2008; Nairne, Thompson, &

Pandeirada, 2007), pleasantness-processing task, and schematically- and contextually-rich processing tasks (e.g., moving, vacationing; Butler, Kang, & Roediger, 2009; Nairne &

Pandeirada, 2008; Nairne, Thompson, & Pandeirada, 2008; Weinstein, Bugg, & Roediger, 2008).

The survival-processing effect also extends to some visual processing tasks, such as remembering details of pictures (Otgaar, Smeets, & van Bergen, 2010), but not others, such as real or pictured faces (Savine, Scullin, Roediger, 2011).

After establishing a consistent survival-processing effect, researchers appealed to several well-established influences on memory as proximate explanations for the effect. The first potential proximate explanation for the survival-processing effect is the congruity effect. To PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 24 examine the possible contribution of the congruity effect to the survival-processing advantage,

Nairne, Thompson, & Pandeirada (2007) compared the recall of words rated high in relevance

(which were conceptualized as being similar to responding “yes”) to the words rated low in relevance (which were conceptualized as being similar to responding “no”). Relevance rating comparisons produced mixed results; memory was better for words given high relevance ratings, consistent with the congruity effect. That is, more relevant (i.e., “yes” response) words were remembered better. However, the survival-processing effect persisted under conditions in which ratings of pleasantness (Experiment 1) and of self-relevance (Experiment 2) tended to be higher than ratings of fitness-relevance or moving-relevance (see also Nairne, Thompson, &

Pandeirada, 2008). This suggests that congruity effects do not explain the survival-processing advantage. The congruity effect would result in better memory for words processed for pleasantness, for example, but the survival-processing effect persisted. Consistent with this finding, other research has controlled for congruity effects and the survival-processing advantage has remained (e.g., Nairne & Pandeirada, 2008; see also Nairne & Pandeirada, 2011).

In contrast to these findings, other research has demonstrated that the survival-processing effect disappears when controlling for congruity effects (Experiment 1, Butler, Kang, &

Roediger, 2009) and when manipulating the congruity of the word stimuli to the processing task

(Experiment 2, Butler, Kang, & Roediger, 2009). In fact, the condition in which the stimuli and processing task were congruent produced the best memory, regardless of processing task.

Palmore, Garcia, Bacon, Johnson, and Kelemen (2012) also found that the survival-processing effect was completely accounted for by the congruity of word stimuli and the processing task.

A second possible explanation for the survival-processing effect is that it invokes self- referential processing (see Klein, 2012 for a review). Kang, McDermott, and Cohen (2008) PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 25 removed self-referential processing from the study by using videos of third person scenes. They found the survival-processing effect persisted in the absence of self-involvement in the scenario.

However, Weinstein, Bugg, & Roediger (2008) assessed the role of the self-reference effect in the survival advantage by comparing participants who read the scenarios with respect to another person to participants who read the scenarios with respect to themselves. If the survival- processing effect can be explained, at least in part, by self-referential processing, then memory should be worse for those in the third person condition. Memory performance on a recall task did not vary significantly across the first person and third person conditions, indicating that the role of self-referential processing in the survival advantage was negligible.

A third possible explanation for the survival-processing advantage involves the contextually rich, or novel nature of the fitness-relevant scenarios used in these experiments.

Surviving in the grasslands of a foreign country certainly seems far more novel and arousing than planning a move. Nairne, Thompson, and Pandeirada (2007) found a strong positive correlation (r = .35) between emotionality ratings of the words and overall recall, but almost no correlation between emotionality and survival advantage (r = -.01). Kang, McDermott, and

Cohen (2008) tested this explanation by comparing the survival scenario to a control group that was designed to match it in arousal and novelty. They compared the survival-processing task to a task involving planning a bank heist. Across three experiments, the survival-processing task produced greater recall than the bank heist processing task and a pleasantness processing task.

Weinstein, Bugg, and Roediger (2008) also controlled for potential differences in novelty. They instructed each participant to rate the relevance of a list of words to the traditional survival scenario (ancestral survival) or to a modern-day survival scenario (which was identical in wording to the ancestral survival scenario except for the words “city” and “attacker” replacing PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 26

“grasslands” and “predator,” respectively). Participants performed the typical incidental learning task by first reading one of three scenarios: ancestral survival, modern-day survival, or moving.

They then rated the relevance of each of several words to the scenario, engaged in a distractor task, and then performed a surprise recall task. The survival advantage persisted. Those participants who rated the relevance of words to the ancestral survival scenario recalled more words than those who rated the relevance of words to the present-day survival scenario. Taken together, these findings suggest that greater novelty or arousal could not explain the survival advantage in memory. Additionally, the use of other contextually rich encoding scenarios such as moving, going on vacation, planning a bank heist, and planning dinner does not eliminate the survival-processing effect. However, Röer, Bell, and Buchner (2013; see also Kroneisen &

Erdfelder, 2011) contend that richness and distinctiveness of the fitness-relevant processing tasks account for the improvement in memory that accompanies this task.

A related explanation for the survival-processing effect appeals to the emotionally- arousing and strongly valenced nature of the fitness-relevant context and stimuli. Nairne,

Thompson, and Pandeirada (2007) found a significant negative correlation between emotionality and survival rating, r = -0.20. Otgaar, Smeets, and van Bergen (2010) found that, regardless of processing task, high arousal pictures were better recalled than low arousal pictures.

Additionally, the survival-processing effect persisted; both high- and low-arousal pictures were more likely to be recalled in the fitness-relevant processing task than in the moving-relevant and pleasantness-processing tasks. Similarly, regardless of processing task, high-pleasure pictures were more likely to be remembered than low-pleasure pictures. High- and low-pleasure pictures were more often remembered in the survival processing task than in the moving and pleasantness processing tasks. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 27

Howe and Derbish (2010) found mixed results regarding emotionally laden stimuli.

Words inherently related to survival (survival words) were recognized as well as neutral words, but better than negative words in Experiment 1. However, in Experiment 2b, survival words were more likely to be recognized than both neutral and negative words. Additionally, survival lists led to greater recall, regardless of processing task. In Experiment 3 the two emotionally charged lists were equated on arousal. Results indicated better recall for neutral words than survival words, and better recall for survival words than negative words. Additionally, better recognition occurred for survival and neutral words than negative words. Results indicated similar recognition memory for survival and neutral words. Combined, this evidence suggests that at least part of the survival-processing effect cannot be accounted for by the emotional valence of stimuli.

Another candidate for the proximate mechanism of survival-processing is the presence of both relational and item-specific processing. Information can be processed in a relative way (i.e., relational processing), a non-relative way (i.e., item-specific processing), or a combination of the two. Recall that relational processing involves encoding information with respect to commonalities present in information in the environment during encoding (i.e., the relationships between the information being encoded), whereas item-specific processing involves encoding individual characteristics that are specific to each piece of information. Repeated combination of both produces the best memory performance.

Evidence for the role of relational processing in the survival-processing effect is mixed.

Nairne and Pandeirada (2008) compared the effects of survival- and pleasantness-processing of already categorized words (which is inherently a relational processing task) on recall and recognition. Pleasantness-processing acts as an item-specific processing task. So asking PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 28 participants to engage in pleasantness-processing of a categorization task presumably initiates both types of processing on the words. However, instructions to engage in one type of processing over the other might affect reliance on a given type of processing. Results from between-

(Experiment 1) and within-participant (Experiment 2) studies showed that the survival- processing effect persisted in recall even though the two tasks were equated on relational processing by using the categorized word list. Additionally, comparisons of adjusted ratio of clustering (ARC) scores (Roenker, Thompson, & Brown, 1971), which to indicate relational processing in free recall tasks, showed that the survival- and pleasantness-processing instructions produced similar amounts of relational processing.

In contrast, Howe and Derbish (2010) found that survival-processing effects disappeared when relational processing was controlled by equating the number of themes of available in associative word lists. Fewer themes produced greater relational processing (Howe & Derbish,

2010). When the difference in number of themes was maximized, the survival-processing effect returned. Howe and Derbish examined these effects using a yes/no recognition task. Similarly, in four experiments, Burns, Burns, and Hwang (2011) compared survival-processing to other processing tasks involving relational-processing, item-specific processing, or both. The survival- processing effect disappeared when compared to a control processing task that employed both types of processing. This provides strong support for the hypothesis that survival-processing involves both relational and item-specific processing.

Howe and Derbish (2010) also examined the effects of different materials during encoding. Specifically, they examined the effects of either survival- or pleasantness-processing on true and false recognition of survival, neutral, or negative words. Results indicated that survival-processing and survival words always produced low net accuracy, defined as proportion PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 29 correct. Additionally, survival-processing resulted in more false alarms than did pleasantness- processing: The survival list, independent of processing task, always produced the greatest number of false alarms (Howe & Derbish, 2010). However, negative lists produced the most number of false alarms when processed for survival-relevance. Survival-processing and survival concepts did not increase false alarms for all distractors, but only those that were semantically related to survival.

The role of planning for the future has also been examined as a potential explanation for the survival-processing effect. Planning for a future event seems inherent in the survival scenarios that are typically used in studies of the survival processing effect (see Nairne,

Thompson, & Pandeirada, 2007). However, the two variables, planning and survival, can be untangled in order to assess the contribution of each to the benefit in memory. In a series of experiments, Klein and colleagues (Klein, Robertson, & Delton, 2010; 2011) examined recall after an encoding task that involved rating words for their relevance to either a survival scenario containing a planning component, a survival scenario without a planning component, or a planning scenario without a survival component. They found superior recall after the survival with planning and planning without survival tasks as compared to the survival without planning task. This suggests that planning, rather than the survival-related context itself, improves memory. However, the similar amount of true recall in survival-processing and survival-without- planning scenarios does not in itself lead to the conclusion that planning is in part, or wholly, responsible for the survival-processing effect. Similar levels of recall could occur for numerous reasons. Examining only true recall, as was done in the planning studies, conflates decision variables that may differ between groups but result in similar memory performance outcomes.

Additional evidence of a different type can elucidate the underlying mechanisms in each of these PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 30

encoding tasks.

Another proximate explanation of the survival-processing effect appeals to false memory.

Otgaar and Smeets (2010) found that survival processing increases true and false memory in children and adults. The existence of increased intrusions accompanying increased true recall in recall tasks (e.g., Nairne, Thompson, & Pandeirada, 2007), as well as increased false alarms accompanying hits in recognition tasks (e.g., Howe & Derbish, 2010), suggests that participants engaging in survival processing might hold a more liberal internal criterion for responding that a word was previously experienced. That is, participants might have a more liberal bias when they have recently processed words for survival relevance. In fact, when calculating d' and c from the hit rate and false alarm rates provided by Howe & Derbish (2010), this pattern emerges. Note that subscripts SP and P indicate survival processing and pleasantness, respectively. In

Experiment 1, for data including only critical lures in the noise distribution, d'SP = 1.076, whereas d'P = 1.449. Additionally, cSP = -0.59, whereas cP = -0.08. This pattern of results means that the ability to correctly classify a word as old or new (i.e., accuracy) was better in the pleasantness processing task than the survival-processing processing task. Additionally, a bias toward classifying new words as old is evident in the survival-processing processing task, whereas almost no bias was evident in the pleasantness processing task. Stated another way, a bias toward accepting false alarms existed in the survival-processing processing task, but not in the pleasantness processing task.

Recall that Howe and Derbish (2010) found that the greater false alarms could be attributed to a higher number of semantically-related intrusions rather than any kind of word. For data including only related lures (and presumably excluding critical lures), d'SP= 2.162, whereas d'P= 3.172. Additionally, cSP= -0.045, whereas cP= 0.78. This pattern of results means that the PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 31 ability to correctly identify a word as old or new (accuracy) was better in the pleasantness processing task than the survival-processing processing task. Additionally, a bias toward classifying old words as new was evident in the pleasantness processing task, whereas almost no bias was evident in the survival-processing processing task. Stated another way, a bias toward incorrectly identifying old words as new existed in the pleasantness processing task, but not in the survival-processing processing task. Unfortunately, the information regarding unrelated lures was not reported.

Taken together, this pattern of results suggests that participants might adopt a more liberal criterion after processing words for their survival advantage than for pleasantness.

Furthermore, when words are less related to the target words, the criterion approaches zero. With respect to the evolutionary explanation, this cognitive bias makes sense.

The evolution of cognitive biases: Error management theory. Error management theory

(EMT; Haselton & Buss, 2000) provides a way to understand how cognitive biases may evolve.

EMT holds that natural selection favored decision rules resulting in more beneficial--and less costly--consequences. Over evolutionary history, the existence of an asymmetry in the costs and benefits of each decision option probably evolved in a manner that resulted in biases that improved the probability of survival and reproduction.

A common analogy used to illustrate error management theory is that of a smoke detector. Smoke detectors can be thought of as decision tools created by humans to operate with a liberal bias in detecting signals. Smoke detectors tend to maintain a relatively low threshold for detecting a signal. This low threshold makes sense when considering the costs and benefits of each error. That is, missing a fire signal when one exists (Type II error) carries heavier costs

(e.g., possible death) than incorrectly detecting a fire signal that was not present (Type I error; PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 32

e.g., taking time to check for a non-existent fire).

Consistent with error management theory, researchers have shown that humans acquire fears much more quickly when the stimuli include things that would have presented a survival- related problem. People develop aversions much more quickly to spiders, snakes, and heights than to modern threats to survival (e.g., cars, guns, etc.) or other non-survival related stimuli (see

Ohman & Mineka, 2001). This evidence suggests that error management theory may be an adequate explanation for cognitive biases.

Consistent with this explanation of cognitive biases, humans may have evolved a bias toward setting a liberal criterion for decisions when survival is salient. This is different from the idea that survival-processing results in greater and more accurate recall than other encoding strategies. If a cognitive bias exists, then an increase in hits should be accompanied by an increase in false alarms, reducing the overall accuracy of retrieval. This is in line with the research finding that when accounting for intrusions in recall tasks and false alarms in recognition tasks, survival processing produces no better memory performance than control processing tasks. The current research seeks to statistically confirm this pattern of results using signal detection measures.

Summary and Overview of Present Research

The survival-processing effect, or the increase in memory performance when processing information for its fitness relevance, sometimes disappears when controlling for other well- known influences on memory. For example, Klein and colleagues (Klein, Robertson, & Delton,

2010; 2011) demonstrated that the relative benefit of survival processing on true recall performance over comparison groups does not manifest when comparing the survival processing task to a planning without survival processing task. However, the benefit is seen when PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 33 comparing both planning groups to a survival without planning group. This provides preliminary support for the claim that planning plays some role in the typically observed survival-processing effect. However, a reduction in the discrepancy between rates of correct memory performance does not provide strong enough evidence to warrant the conclusion that these variables are, in part or wholly, responsible for the survival processing effect. Klein, Robertson, and Delton

(2011) suggest that this does not mean that the source of the similar recall between survival processing and planning (without survival) processing can be attributed to the same cause. In fact, similar recall after these two processing tasks could occur for numerous reasons. Additional evidence of a different type can help elucidate similarities and differences between these processing tasks.

Assessing only correct recall or only recognition conflates the effects of different cognitive processes that almost certainly contribute to the memory process. Specifically, decisions about information must be part of the memory process, but have not been examined with respect to the survival-processing effect. The signal detection theory provides a theoretical and methodological model for examining decisions.

Two important characteristics of the decision process can be assessed within the signal detection paradigm. Discriminability is the ability to correctly discern whether a piece of information is noise or signal. Thud, discriminability is a form of accuracy. People presumably make decisions by comparing the value of the strength of evidence to a subjective decision criterion. If the strength of evidence exceeds the value of the criterion, then people respond as if a signal is present. Otherwise, people respond as if no signal is present. Bias, within the signal detection framework, refers to an a priori tendency to prefer one response to the other. A liberal bias means that there exists an a priori preference for responding as if a signal is present; a PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 34 conservative bias means that there exists an a priori preference for responding as if no signal is present. This can also be measured within the signal detection framework. Discriminability and bias can provide additional information about the survival-processing effect thus allowing researchers to update their beliefs about the proximate mechanisms responsible for the survival- processing effect.

Finally, research demonstrates that an increase in false memories, especially for semantically-related stimuli, consistently accompanies the increase in true recall and recognition.

This lends credibility to the argument that the survival-processing effect occurs, at least in part, because of a bias. Statistical analyses that provide more detailed information about the decision process involved in recognition allow a direct examination of this idea. More specifically, one can examine the tendency for people to favor a particular response using signal detection theory.

Patterns in published data demonstrate that a more liberal bias exists in the survival- processing tasks than pleasantness processing tasks. However, equivalent statistics cannot be calculated from the studies that assess the role of planning. Further, a statistical comparison of signal detection measures can elucidate whether the decision process that results in increased false memories with regard to semantically-related intrusions differs from the decision process for semantically-unrelated information. Perhaps the increased false memory rate for semantically-related information occurs because of a more liberal bias, a reduced ability to discriminate between old and new words, or more likely, both.

The present research sought to replicate and extend previous experimental evidence for the survival-processing effect. First, the current research replicated the methodology and used the planning processing task employed by Klein, Robertson, and Delton (2011). Second, the current research examined the effect on recognition memory using lists of three types of highly PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 35 associated abstract and concrete words (i.e., positive, negative, neutral), and measures of accuracy and bias based in the signal detection framework. Participants performed an incidental learning task in which they rated words for their relevance to one of several scenarios: grasslands survival with planning, grasslands planning without survival, non-grasslands planning-without- survival, or pleasantness. They then completed a distractor task, followed by a surprise free recall test. Finally, participants completed a yes/no recognition task that included lures that were

(a) highly associated to targets (i.e., critical lures), (b) moderately associated to targets (i.e., related lures), and (c) not associated to targets (i.e., unrelated lures).

This research seeks to answer a series of related research questions. How does a signal detection analysis inform us about the characteristics of the survival-processing effect compared to other well-established effects on long-term memory? How do signal detection measures inform us about the role of planning in the survival-processing effect? Is the survival processing effect explained more simply through the combination of relational and item-specific processing? How can signal detection evidence inform us about the nature of false memories in the survival-processing effect?

Based on the data from previous studies, it seems appropriate to compare Roediger and

McDermott’s (1995; see also Wixted & Stretch, 2000) model of false memory against a model that includes a liberal criterion shift as possible models of the survival processing effect.

Evidence from recognition tasks suggests that survival-processing tasks produce both reduced discriminability and a liberal bias. Moreover, the pattern of results suggests that the criterion value is almost always lower (i.e., more liberal/less conservative) for the survival-processing tasks than other processing tasks. The false memory model of Roediger and McDermott (1995) does not account for the criterion measure at all. Additionally, error management theory PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 36

(Haselton & Buss, 2000) contends that natural selection favored decision rules that resulted in less costly consequences. For example, it is less costly to jump away from a stick that was mistaken for a snake than to be bitten by a poisonous snake that was mistaken for a stick. This probably resulted in biases that improve the probability of survival and reproduction. Thus, a liberal cognitive bias might be expected for information that activates decisions about survival. It is better to falsely recognize important survival information than to miss important survival information. Combined with the evidence from other recognition studies previously mentioned, this suggests that a liberal cognitive bias may partially explain the increased rate of false alarms in the survival-processing effect.

If the survival-processing effect involves a unique contribution to memory above and beyond planning, then the survival processing task should produce greater correct recall and recognition than the non-survival planning control processing tasks. If survival-processing involves a unique contribution to false memory above relational processing, then greater false memory should occur in the survival processing task compared to the other relational processing tasks. However, if this effect is driven by the presence of highly related information rather than survival, per se, then only differences in type of lures in the recollection environment should exist. If false memory in the survival processing effect is driven by a more liberal decision criterion during the memory retrieval process, then the survival processing task should produce a lower criterion value than the other processing tasks.

PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 37

CHAPTER II: EXPERIMENT 1

This research seeks to examine the effects found by Klein, Robertson, and Delton (2011) of planning and survival processing on recall memory, and to extend the findings to recognition memory using different word stimuli. Rather than food-related stimuli, the present research seeks to extend the findings to highly associated words lists containing abstract and concrete nouns.

This experiment included a pleasantness processing task, which allowed comparisons of decision characteristics of the survival- and planning-processing effects to another semantic processing task that also benefits memory performance. Additionally, this experiment includes an encoding processing task that is similar to all aspects of the grasslands survival scenario except for the goals involved. Specifically, the new processing task removes the survival salience and replaces it with other goals that include planning (i.e., protect photo equipment, find interesting things to photograph, etc.). Memory performance was assessed with a free recall and a yes/no recognition test. The relatedness of information in the recognition environment was manipulated to create environments with (a) highly related information, (b) moderately related information, and (c) unrelated information. (Note that the to-be-memorized words, as well as the recognition lures, were the same for all encoding processing tasks.) However, an error in the procedure restricted me from performing analyses on this variable. (The procedural error was corrected and this variable was examined in the second experiment.) Signal detection measures of discriminability and bias were computed and compared across processing tasks.

If, as Klein et al (2011) suggests, planning explains the survival processing effect, then all planning processing tasks should produce greater true and false recall and recognition than the pleasantness processing task. If, as Nairne and colleagues (e.g., 2011) suggest, survival processing is a special domain of information that uniquely promotes true and false recollections PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 38 then the survival processing task should produce greater true and false recall and recognition than the non-survival planning processing tasks.

Method

Participants. Approximately two hundred and forty-four participants were recruited from

George Washington University, Georgetown University, and Bowling Green State University.

George Washington University and Georgetown University are located in Washington DC and attract a large number of international students. Bowling Green State University is located in northwest Ohio. Participants responded to online advertisements that were posted to an online participant recruitment tool at George Washington University and Bowling Green State

University. Additionally, participants responded to recruitment emails were sent to these selected departments within these universities. Participants received research credit for psychology classes or extra credit in other classes in exchange for their participation and were able to enter their name in a raffle for one of eleven $25 gift cards. The drawing commenced at the end of data collection and winners were notified by email.

Six participants were not included in the analyses because they failed to complete the study. In two instances, the participants had problems with the experiment website: The website returned the participants to the beginning of the study after they had completed approximately half of the experiment. The participants then proceeded through the procedure again as a new participant. Both cases for each of these participants were removed from analyses to reduce the possibility that being exposed to two between-participants groups and/or participating in part of the study already impacted the dependent variables. One participant failed the attention check question, which resulted in the data being excluded from analyses. Data from four participants PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 39 were excluded because they failed to follow directions during the recognition task. Additionally, one case was removed from the analysis on recall data because no responses were provided.

The remaining sample consisted of 75 males (32.5%), 155 females (67.1%), and 1 person

(0.4%) who provided no answer about gender between the ages 18 years to 36 years old (M =

19.94, SD = 1.81). Thirty-one percent of participants were university freshman, 19% were sophomores, 9% were juniors, 41% were seniors, and <1% were either a college graduates or graduate students.

Most participants self-identified as Caucasian (61%), but the sample was considerably diverse and contained people identifying as Asian-American/Pacific Islander (14% ), African-

American (13% ), Hispanic/Latino (6%), and “Other” (7%), including three percent of the entire sample identifying themselves as Asian. The “other” category also encompassed the following ethnicities that were endorsed by a single participant (<1% of the sample): Afghan-American,

African, Caucasian-Hispanic, Chinese, Indian, Jamaican-Chinese, Middle Eastern, Pacific

Islander/Caucasian, & South Asian.

All but one participant attended college or university. Most participants attend university in the Washington DC metro area. Forty-four percent of participants attend George Washington

University, 38% attend Georgetown University, and 17% attend Bowling Green State University.

One person did not report their university status.

Participants were randomly assigned to an encoding processing task. Twenty-six percent

(n = 59) were assigned to the Grasslands Photoshoot processing task (i.e., grasslands-planning- without-survival) , 24% (n = 56) were assigned to the Grasslands Survival processing task (i.e., grasslands-survival-with-planning) , 25% (n = 58) were assigned to the Dinner Party processing task (i.e., non-grasslands-planning-without-survival), and 25% (n = 58) were assigned to the PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 40

Pleasantness processing task. Additionally, participants were randomly assigned to one of three versions of the recognition task. (This was an order variable inserted to control for possible order effects in recognition.) Approximately 33% were assigned to each recognition list.

Materials and design. The experiment was a 4 (Processing Task: grasslands-planning- without-survival, grasslands-survival-with-planning, non-grasslands-planning-without-survival, pleasantness) x 3 (Lure Type: critical, related, unrelated) mixed factorial design, with processing task as a between-participants variable and lure type as a within-participants variable. However, due to an error in the procedure during the ratings and recognition task, the within-participants variablecould not be examined. Thus, the experimental design tested was a simple one-factor design with four groups. Lures involved in the recognition task included information that was highly related, moderately related, and unrelated to the studied word lists. Targets and lures both consisted of words from positive, neutral, and negative word lists. Both lure type and valence were the same across processing tasks.

Participants completed the experiment in a computer lab. Participants were encouraged to use incognito or private browsers to increase their privacy. (Such browsers do not collect browsing history when in use). Qualtrics, a web-based research suite, hosted the experiment.

Participants from Bowling Green State University completed the experiment on Dell

Optiplex 780 desktop computers with a Pentium® 4 processor and 4GB of RAM. The monitors were 19-inch flat panel, wide format (16:9) Dell monitors and the screen resolution was 1440 x

900 pixels. The operating system was Windows XP Service Pack 3. Participants accessed the web-based experiment using Firefox version 23 web browser.

Participants from George Washington University completed the experiment on Dell PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 41

Optiplex 960 desktop computers with an Intel® Core™ 2 Quad processor and 4 GB of RAM.

The monitors were 22 inch Dell monitors and the screen resolution was 1920 x 1080 pixels. The

operating system was Windows 7 (32 bit). Participants accessed the web-based experiment using

Google Chrome version 29 web browser.

Finally, participants at Georgetown University completed the experiment on Lenovo

desktop computers with an Intel® Core™ i5-3470s 2.9gHz processor 8 GB of RAM. The

monitors were 21 inches and the screen resolution was 1920 x 1080 pixels. The operating system

was Windows 7 Enterprise. Participants accessed the web-based experiment using Firefox

version 26 web browser.

Stimuli. Word stimuli were selected in a similar manner used by Howe and Derbish

(2010). Fifteen word lists consisting of ten high associates of each (a) neutral (deer, leg, paper,

same), (b) negative (hurt, sick, death, sad, bad), and (c) positive (air, water, party, funny, fruit,

mountain) critical lures were equated on backward associative strength (see Appendix A for the

full list of stimuli and critical lures).1 Thus, one hundred fifty words served as test stimuli presented in random order.

Rating task. Participants were instructed to rate the word stimuli with regard to their

relevance to a hypothetical scenario or with regard to the degree of pleasantness. Ratings were

made on a five-point scale with word labels identifying each option (Extremely

Irrelevant/Unpleasant, Somewhat Irrelevant/Unpleasant, Neutral, Somewhat Relevant/Pleasant,

Extremely Relevant/Pleasant). Participants were instructed to respond to each item within five

seconds. The experiment automatically progressed to the next word after seven and a half

seconds. Participants were informed that the task would take 10-15 minutes. Participants in the

1 Due to a procedural error, the words from six lists created from positive lures and four lists created from neutral lures were presented during the rating task instead of words from five lists of each valence. This was corrected in Experiment 2. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 42 scenario processing tasks saw the following instructions.

Below is a description of a scenario in which you might find yourself. Over the next 2

minutes, please think about and visualize the scenario in your mind. Try to create a rich

visual image of the situation described, as if you are really experiencing the situation.

[The participant would see the scenario description here.]

While the counter below counts down to zero, please follow the imagination instructions

(above). When the counter reaches zero, a button will appear below to advance to the

next page.

The scenarios descriptions were as follows.

Grasslands photo. “Imagine that you are going to visit a grassland to take photographs of

the geography, vegetation, and wildlife. Pay attention to all of the feelings and thoughts

that go through your mind as you think about and plan how you're going to protect your

photographic equipment, find interesting objects and scenes to photograph, and have

adequate lighting for the photography.”

Grasslands survival. “Imagine that you are going to be stranded in the grasslands without

any basic survival materials. You’ll need to find steady supplies of food and water and

protect yourself from predators. Pay attention to all of the feelings and thoughts that go

through your mind as you think about and plan for being stranded in the grasslands.”

Dinner party. “Imagine that you are planning a dinner party for the weekend. You plan to

go to the store to purchase food, drinks, and other party supplies. Because you are not

sure of the guests’ food preferences, you plan on purchasing a variety of different things.

Pay attention to all of the feelings and thoughts that go through your mind as you think PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 43

about and plan for the dinner party.”

Instructions for the pleasantness processing task were slightly different:

“On the next page, you will see the first of a series of words. For each word, please take a

moment to consider how pleasant the word seems to you. Please rate on the scale

provided below each word the degree of pleasantness that you associate with that word.

You have 5 seconds to rate each word. This task will last 10-15 minutes.”

Distraction task. The distraction task consisted of fifteen moderately difficult multiplication problems. The task duration was five minutes. Participants were instructed to take their time and make sure their answers were correct. Most participants used scratch paper to work through the problems, but were not allowed to use a calculator. Participants who finished the distraction task before five minutes elapsed were instructed to check their work.

Recall task. The surprise free recall task appeared after the distraction task. Participants were provided the following instructions. “Please think about the first part of this study during which you rated a series of words. Over the next five minutes, please try to recall as many of the previously presented words as you can. In the box below, type every word that you recall. Press

'enter' after each word to type each word on a new line. When the timer (above) reaches zero, you will be directed to the next page. Please try to record as many words as possible before this happens.”

Attention check. An attention check was included after the recall task to ensure that participants were paying attention. Participants were instructed to type the number "37" into the text box. Those who failed to follow directions (n = 1) were excluded from all analyses.

Recognition task. The recognition task consisted of 45 words randomly chosen from the word stimuli presented in the learning task, 15 critical lures, 15 moderately associated lures, and PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 44

15 unassociated lures (see Appendix B). Moderately associated lures were chosen because they

were the 11th highest associates on the word lists created from critical lures. Unrelated lures

were selected because the relationship with the critical lure was weaker than .02.

Due to an error in the procedure, the lures and targets associated with the positive critical

lure “mountain” were not presented during the recognition task. Instead, the lures and targets

associated with the neutral critical lure “ship” were presented. Additionally, the critical lure

“leg” was presented to all participants twice during the recognition task, once as a critical lure

and once as a target. These words were removed from analyses. It is difficult to know what, if

any, effect these errors had on recognition responses or results. Thus, the results represent overall

recognition scores rather than individual lure type scores. The errors were corrected in

Experiment 2.

Participants were randomly assigned to one of three versions of the recognition word list.

Each recognition word list consisted of three blocks that were presented in random order. One

block of words contained a subset of the target words (i.e., Subset A) and the critical lures. A

second block contained another subset of target words (i.e., Subset B) and the moderately

associated lures. A third block contained the final subset of target words (i.e., Subset C) and the

unrelated lures. Each version of the recognition list consisted of a different combination of each subset of the target words and type of lure. All target words in the recognition task were rated in the same block as all types of lures, but between participants. The words appeared to participants as one continuous list, with each word appearing individually in the center of the computer screen for up to seven seconds.

For each word, participants indicated whether the word on the screen was presented

during the first part of the study (“Old”) or was not presented before (“New”). Participants were PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 45

instructed to respond within five seconds. After an answer was given, or a total of seven seconds passed since the word appeared on the screen, the next word appeared in its place.

Ease of visualization and narrative descriptions. Following the recognition task, participants in the scenario processing tasks (but not the pleasantness processing task) also provided a rating of the ease of visualizing the scenario on a five-point scale with word labels

(Very Difficult, Difficult, Neutral, Easy, Very Easy). Additionally, participants in the scenario processing tasks (but not the pleasantness processing task) provided narrative descriptions of their visualization (see Appendix C for sample narrative descriptions).

Procedure. Participants completed the study in the same session as other participants. The number of participants engaging in the study present in any session ranged from one to nine.

Despite signage on the door that a study was in progress and instructions not to disturb the study, occasionally other non-participants entered the computer lab and quietly used a computer. At any given time, no more than four non-participants were in the computer lab during a session, but it was atypical for any non-participants to be present.

Participants sat in front of a desktop computer upon arriving at the computer lab. When all participants had arrived for the session, participants were introduced to the study and instructed to read through the informed consent that was visible on the computer screen in front of them. Participants were instructed to refrain from using a calculator during the math portion and told that they could use scratch paper. Participants were asked to remain quiet and sit patiently upon finishing. When all participants finished, they were thanked and excused.

Before agreeing to complete the study, the participants asked any questions they had. A few questions were asked about how to get credit for participating in the study and a couple PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 46 people asked how to get the results of the study. After all questions were answered, participants agreed to participate in the study. Once agreeing to the informed consent, each participant was randomly assigned to one of the encoding processing tasks.

After reading the instructions, participants either visualized the scenario for five minutes or, in the case of participants in the pleasantness processing task, proceeded to the rating task.

After visualizing the scenarios for five minutes, participants in the other processing tasks also proceeded to the rating task. During the encoding (i.e., learning) stage, participants in the pleasantness processing task rated the pleasantness of 150 words. Participants in the three planning visualization processing tasks provided ratings of the relevance of each word to the scenario they visualized. Each word appeared in the center of the computer screen for a maximum of seven seconds. After completing the ratings for all 150 words, instructions for the distractor task appeared on the screen.

Participants then completed the second stage of the study (the retention interval), in which they calculated fifteen moderately difficult multiplication problems for five minutes.

Following the distraction task, instructions for the third stage of the study appeared on the screen. Participants were given five minutes to report as many words as they could remember rating during the first part of the study. Participants typed all words into the computer. Following the recall task, participants completed the attention check and then proceeded to the old/new recognition task.

Participants in the scenario processing tasks then rated the ease of visualization and provided a narrative description of their visualization. Participants in the pleasantness processing task proceeded to the demographics.

Finally, participants reported general demographics. After completing the study, PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 47 participants entered their contact information for the raffle prize. Participants were thanked for their participation, credited for their participation, and dismissed.

Results

Ease of visualization. Ease of visualization was not significantly correlated to the recall or recognition measures. A univariate analysis of variance on ease of visualizations indicated a

2 significant main effect of processing task, F(2, 169) = 6.44, p = .002, ηP = .07, observed power

= .90. Independent samples t tests confirmed that the participants in the dinner party processing task (M = 4.10, SD = .79) found the scenario easier to visualize than participants in the grasslands photo processing task (M = 3.57, SD = .92), t(114) = -3.36, p = .001, d = .62, 95% CI

[-.85, -.22]. Participants in the dinner party processing task found the scenario easier to visualize than the participants in the grasslands survival processing task (M = 3.63, SD = .93), t(112) = -

2.98, p = .004, d = .55, 95% CI [-.80, -.16]. No other differences were statistically significant.

Ratings. Average ratings were significantly correlated with all three measures of recall: exact match (r = .20, p = .002), phonetic match (r = .21, p = .002), and possible match (r = .20, p

= .003). Additionally, average ratings were significantly correlated with d' (r = .23, p = .002), hit rate (r = .34, p < .001), criterion (r = -.16, p < .04), and proportion correct recognition (r = .19, p

= .01).

A univariate analysis of variance was performed on the average ratings. Levene’s test indicated a violation of the assumption of equality of variances, F(13, 217) = 3.47, p < .001. A

2 main effect of processing task was significant, F(3, 217) = 43.46, p < .001, ηP = .38, observed power > .99. Independent samples t-tests confirmed that the grasslands survival processing task

(M = 3.09, SD = .46) produced higher relevance ratings than the grasslands photo processing task

(M = 2.62, SD = .49), t(113) = -5.28, p < .001, d = .99, 95% CI [-.65, -.29]. The grasslands PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 48 survival processing task produced higher ratings than the pleasantness processing task (M = 2.92,

SD = .18), t(70.45) = 2.61, p = .01, d = .49, 95% CI [.04, .30]. The grasslands survival processing task produced higher ratings than the dinner party processing task (M = 2.23, SD = .43), t(112) =

10.44, p < .001, d = 1.93, 95% CI [.70, 1.03]. See Figure 1.

The grasslands photo processing task produced higher relevance ratings than did the dinner party processing task, t(115) = 4.64, p < .001, d = .85, 95% CI [.23, .57]. The pleasantness processing task produced greater ratings than did the grasslands photo processing task, t(72.70) =

-4.41, p < .001, d = .81, 95% CI [-.44, -.16]. The pleasantness processing task also produced higher ratings than did the dinner party processing task, t(75.65) = -11.48, p < .001, d = 2.09,

95% CI [-.82, -.58].

Recall. The recalled words were categorized into one of three categories: exact match, phonetic match, and possible match. Possible matches include words that were very close in phonetic or physical characteristics of the target stimuli, but contained typographical errors (e.g.,

“attitide” was coded as a possible match to “attitude”). Possible matches include words that match the target word except for the singular or plural form of the presented word. Words not categorized as belonging to one of these three categories were categorized as intrusions.

Two coders independently categorized the intrusions as phonetic or possible match or no match to the target words. Of the 427 recalled words that were not exact matches to the target words, the two coders agreed on 385 of the categorizations (90% agreement). The two coders discussed the disagreements and resolved 20 of the disagreements (48%). A third coder independently coded the remaining 22 (52%) recalled words that were not exact matches to the targets. In all cases, the third coder agreed with one of the other two coders. The categorization of a word by two independent coders determined the final category assignment of the final 22 PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 49 words.

Correct recall. A series of univariate general linear model (GLM) analyses on the mean number of correctly recalled words was conducted. The first analysis included only recalled items that were exact matches to the previously presented stimuli (i.e., correctly spelled words); the second analysis included recalled items that were phonetic matches to the previously presented stimuli (including exact matches); the third analysis included recalled items that were identical, phonetic, or possible matches.

The top five target words recalled by participants are (in order of most recalled to least): strawberry (138 participants), happy (137 participants), funeral (114 participants), happiness

(111 participants), and arm (110 participants).

With regard to correct recall of the exact stimuli, a significant main effect of processing

2 task existed, F(3, 216) = 4.08, p = .008, ηP = .05, observed power = .84. See Figure 2.

Independent t tests confirmed that the grasslands survival processing task (M =29.23, SD = 9.57) produced a greater number of exact matches during the recall task than did the grasslands photo processing task (M = 25.24, SD = 10.31), d = .40, t(112) = -2.14, p < .04, 95% CI [-7.68, -.29] and the dinner party processing task (M = 21.91, SD = 8.14), t(112) = 4.40, p < .001, d = .82,

95% CI [4.-3, 10.61]. The pleasantness processing task (M = 26. 84, SD = 9.79) produced a significantly greater number of exact matches during recall than did the dinner party processing task, t(114) = -1.95, p = .004, d = .55, 95% CI [-8.24, -1.62]. Although the grasslands photo processing task produced a greater number of exact matches during recall than did the dinner party processing task, this difference only approached significance, t(114) = 1.93, p = .056, d =

.36, 95% CI [-.09, 6.75].

However, when including average rating in the statistical model, the main effect of PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 50 processing task on correct recall of exact matches was no longer significant, F(3, 215) = 2.06, p

2 = .11, ηP = .03, observed power = .52.

With regard to correct recall including phonetic matches to the target stimuli, a

2 significant main effect of condition existed, F(3, 216) = 4.19, p = .007, ηP = .06, observed power = .85. Independent t-tests confirmed that the grasslands survival processing task (M =

29.89, SD = 9.56) produced a greater number of phonetic matches during recall than the grasslands photo processing task (M = 25.29, SD = 10.42), t(112) = -2.28, p = .02, d = .46, 95%

CI [-8.02, -.59] and dinner party processing task (M = 22.62, SD = 8.15), t(112) = 4.38, p < .001, d = .82, 95% CI [3.98, 10.57]. The pleasantness processing task (M = 27.36, SD = 9.75) produced significantly greater phonetic matches during recall than the dinner party processing task, t(114) = -2.84, p < .005, d = .53, 95% CI [-8.05, -1.44]. No other differences were statistically significant.

When adding average ratings as a covariate to the statistical model, the main effect of processing task on correct recall of phonetic matches is no longer significant, F(3, 215) = 2.04, p

2 = .11, ηP = .03, observed power = .52.

With regard to correct recall including all possible matches to the target stimuli, a

2 significant main effect of processing task exists, F(3, 216) = 4.14, p = .007, ηP = .05, observed power = .85. Independent sample t-tests confirm that participants in the grasslands survival processing task correctly recalled more words (M = 30.80, SD = 9.52) than participants in the grasslands photo processing task (M = 26.29, SD = 10.40), t112 = -2.41, p < .02, d = .45, 95% CI

[-8.21, -.81] and the dinner party processing task (M = 23.57, SD = 8.46), t112 = 4.29, p < .001, d

= .80, 95% CI [3.90, 10.58]. The pleasantness processing task (M = 27.90, SD = 9.82) produced more possible matches during recall than did the dinner party processing task, t(114) = -2.54, p = PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 51

.01, d = .47, 95% CI [-7.70, -.96]. No other differences were statistically significant.

When adding average ratings as a covariate to the statistical model, the main effect of processing task on correct recall of possible matches is no longer significant, F(3, 215) = 2.10, p

2 = .10, ηP = .03, observed power = .53.

Intrusions. In this experiment, intrusions were determined based on the three types of possible matches to the target word. When examining only the exact matches, the unique number of intrusions was 427. More than one participant may have recalled some words. Of these, 65 were categorized as phonetic matches to the target words and included in the correct recall analysis for that category. An additional 76 words were categorized as possible matches to the target words and included in the correct recall analysis for that category. Two hundred and eighty-six intrusions remained. Every critical lure and four moderately associated lures were falsely recalled at least once.

Similar to the analysis of correct recall, a series of univariate GLM analyses on the mean number of intrusions was conducted. With regard to the intrusions when only exact matches to the target words were examined, a main effect of processing task exists, F(3, 216) = 5.43, p =

2 .001, ηP = .07, observed power = .93. Independent samples t tests confirm that the grasslands photo processing task (M = 3.95, SD = 3.44) produced a greater number of intrusions than did the pleasantness processing task (M = 2.74, SD = 2.01), t(91.94) = 2.31, p = .02, d = .54, 95% CI

[.17, 2.24]. The grasslands survival processing task (M = 5.27, SD = 4.49) also produced a greater number of intrusions than did the pleasantness processing task, t(75.68) = 3.85, p < .001, d = .73, 95% CI [1.24, 3.81]. Finally, the dinner party processing task (M = 4.47, SD = 2.74) produced a greater number of intrusions than the pleasantness processing task (M = 2.74, SD =

2.01) , t(104.76) = 3.87, p < .001, d = .72, 95% CI [.84, 2.61]. No other differences were PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 52

statistically significant.

This effect of processing task on intrusions when including only exact matches remained significant when including average ratings as a covariate in the statistical model, F(3, 215) =

2 5.95, p = .001, ηP = .08, observed power = .95.

With regard to the intrusions when phonetic matches to the target words were examined,

2 a main effect of processing task exists, F(3, 216) = 5.43, p = .001, ηP = .07, observed power =

.93. Independent samples t-tests confirm that the grasslands photo processing task (M = 3.60, SD

= 3.28) produced a greater number of intrusions than did the pleasantness processing task (M =

2.22, SD = 1.83), t(89.30) = 2.80, p = .006, d = .52, 95% CI [.40, 2.36]. The grasslands survival processing task (M = 4.61, SD = 4.36) produced more intrusions than did the pleasantness processing task, t(73.15) = 3.78, p < .001, d = .72, 95% CI [1.15, 3.62]. Finally, the dinner party processing task (M = 3.76, SD = 2.67) produced more intrusions than did the pleasantness processing task, t(100.74) = 3.12, p < .001, d = .67, 95% CI [.69, 2.38].

The effect of processing task on intrusions when including phonetic matches remained significant when including average ratings as a covariate in the statistical model, F(3, 215) =

2 6.05, p = .001, ηP = .08, observed power = .96. See Figure 3.

With regard to intrusions when all possible matches to the target word were examined, a

2 main effect of condition exists, F(3, 216) = 4.91, p = .003, ηP = .06, observed power = .91.

Independent samples t tests confirm that the grasslands photo processing task (M = 2.90, SD =

3.04) produced a greater number of intrusions than did the pleasantness processing task (M =

1.69, SD = 1.51), t(83.66) = 2.71, p = .008, d = .50, 95% CI [.33, 2.09]. The grasslands survival processing task (M = 3.70, SD = 4.41) produced more intrusions than did the pleasantness processing task, t(69.14) = 3.43, p = .001, d = .61, 95% CI [.86, 3.15]. Finally, the dinner party PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 53 processing task (M = 2.81, SD = 2.40) produced more intrusions than did the pleasantness processing task, t(96.06) = 3.01, p = .003, d = .56, 95% CI [.38, 1.86]. No other differences were statistically significant.

This effect of processing task on intrusions when considering possible matches remained significant when including average ratings as a covariate in the statistical model, F(3, 215) =

2 5.61, p = .001, ηP = .07, observed power = .94.

Recognition. Cases previously mentioned as being excluded and all cases where no response was given to at least one item in the recognition task were excluded from analyses. One hundred seventy nine participants responded to all of the items in the recognition task and are included in these analyses.

For cases where hit rate or false alarm rate was equal to zero or one, a commonly used transformation was computed in calculating the signal detection measures (see MacMillan &

Creelman, 2005). This allows the d' and criterion statistics to be computed for these cases. For each case where the hit rate or false alarm rate equals zero, the following formula was used to calculate a new hit rate: 1 / (2N) where N is equal to the number of items presented. For each case where the hit rate or false alarm rate equals one, the following formula was used to calculate a new hit rate and false alarm rate, 1 - (1 / (2N)) . This resulted in the following percentages of transformations in each lure type block. Transformations were from “0” to “.01” and from “1.0” to “.99.”

A series of GLM univariate analyses with processing task and school as between participants variables was conducted on hit rate, false alarm rate, proportion correct, d' and criterion. School had no effect on any of the dependent variables, so the statistics for school are not reported, but it was kept in the model. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 54

Hit rate. The assumption of equality of error variances was violated, F(12, 166) = 2.04, p

2 = .02 . The main effect of processing task was significant, F(3, 166) = 2.60, p = .054, ηP = .05, observed power = .63 (see Table 2). Independent samples t tests confirmed that the pleasantness processing task (M = .92, SD = .05) produced a higher hit rate than did the grasslands photo processing task (M = .88, SD = .08), t(81.88) = -2.79, p = .007, d = .60, 95% CI [-.07, -.01]. The pleasantness processing task also produced a higher hit rate than did the dinner party processing task (M = .88, SD = .09), t(67.42) = -2.81, p = .006, d = .55, 95% CI [-.08, -.01].

However, when average rating was added to the statistical model as a covariate, the

2 significant main effect of processing task on hit rate disappeared, F(3, 165) = .361, p = .78, ηP <

.01, observed power = .12. See Figure 4.

False alarm rate. No significant main effect of processing task exists, F(3, 166) = 2.21, p

2 = .09, ηP = .04, observed power = 55. However, when adding the average rating as a covariate in the statistical model, the main effect of processing task is significant but has a small effect

2 size, F(3, 165) = 2.86, p = .04, ηP = .05, observed power = .68. Independent samples t-tests confirm that the grasslands photo (M = .28, SD = .04) processing task produced a greater false alarm rate than did the pleasantness (M = .19, SD = .05) processing task, t(90) = 2.80, d =1.99 , p

= .006, 95% CI [.03, .15]. The dinner party (M = .30, SD = .04) processing task also produced a significantly greater false alarm rate than did the pleasantness processing task, t(85) = 2.40, p <

.02, d = 2.43, 95% CI [.02, .20]. No other differences were statistically significant (all p values >

.12). See Figure 5.

Proportion correct. A significant main effect of processing task occurred, F(3, 166) =

2 4.03, p < .01, ηP = .07, observed power = .83. Independent t-tests confirmed that participants in the pleasantness processing task (M = .86, SD = .08) correctly categorized a greater proportion PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 55 of the recognition items than did participants in the grasslands photo processing task (M = .81,

SD = .09), t(90) = -3.04, p = .003, d = .59, 95% CI [-.09, -.02]. Participants in the grasslands survival processing task (M = .84, SD = .07) correctly categorized a greater proportion of words than did participants in the dinner party processing task, (M = .81, SD = .06), t(85) = 2.03, p <

.05, d = .46, 95% CI [.00, .06]. Participants in the pleasantness processing task correctly categorized a greater proportion of the recognition items than did participants in the dinner party processing task, t(85) = -3.46, p = .001, d = .71, 95% CI [-.08, -.02]. No other group differences were significant.

When including average ratings in the full model, the main effect of processing task was

2 still significant but the effect size was reduced to almost negligible, F(3, 165) = 2.68, p = .05, ηP

= .05, observed power = .65. See Figure 6.

2 d'. A significant main effect of processing task exists, F(3, 166) = 4.52, p = .004, ηP =

.08, observed power = .88. Independent t tests confirm that participants in the grasslands photo processing task (M = 1.98, SD = .69) were less able to discriminate between signal and noise items across all types of noise items than were participants in the grasslands survival processing task (M = 2.27 SD = .63), t(90) = -2.09, p = .04, d = -.44, 95% CI [-.56, -.01]. Additionally, participants who read the grasslands photo processing task were less able to discriminate between signal and noise items than were participants who completed the pleasantness processing task (M = 2.46, SD = .69), t(90) = -3.32, p = .001, d = -.70, 95% CI [-.76, -.19].

Participants who read the dinner party processing task (M = 1.97, SD = .50) were less able to discriminate between signal and noise items than were participants who read the grasslands survival processing task (M = 2.26, SD = .63), t(85) = 2.42, p < .02, d = -.51, 95% CI [.05, .54].

Additionally, participants who read the dinner party processing task were less able to PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 56 discriminate between signal and noise than were participants who completed the pleasantness processing task (M = 2.46, SD = .69), t(85)= -3.75, p < .001, d = -.81, 95% CI [-.74, -.23]. See

Figure 7.

The grasslands photo and dinner party processing tasks produced similar d' values, t(89)

= .05, p = .96, 95% CI [-.25, .26]. Additionally, the grasslands survival and pleasantness tasks produced significantly similar d' values, t(86) = -1.35, p = .18, 95% CI [-.47, .09].

However, when including average rating as a covariate in the statistical model, the main

2 effect of processing task on d' was not significant, F(3, 165) = 2.48, p = .06, ηP = .04, observed power = .61.

Criterion. No significant main effects of processing task on criterion existed, F(3, 166) =

2 .37, p = .73, ηP < .01, observed power = .12. See Figure 8.

Summary and Discussion

The results of Experiment 1 suggest that there was a survival processing effect on true recall when compared to other planning processing tasks, but not to a pleasantness processing task. However, when including the average relevance rating in the model, the survival processing effect is not present. Survival processing produced greater false recall than did pleasantness processing. All contextually rich planning scenarios produced greater false recall than the pleasantness processing task. The effect remained when controlling for average relevance rating.

This suggests that false recall might be increased by a variable shared by the three scenario instructions, but not the pleasantness instructions. Possible explanations for this finding include the richness of the scenarios, the narrative aspect of the scenarios, the visualization component of the scenario instructions, the longer time period to introspect about the scenarios, the planning component of the scenarios, a greater amount of relational processing, and/or a PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 57

lesser amount of item-specific processing.

It is possible that the pleasantness processing task produced similar levels of correct recall to the grasslands processing tasks because it involves more item-specific processing than the other processing tasks. This is further supported by the fact that the intrusion rate was higher for the grasslands survival and dinner party processing tasks than the pleasantness processing task. (Item-specific processing is likely to produce lower levels of false memory.)

Despite the error in the procedure in Experiment 1, I was able to examine overall (i.e., collapsed across recognition blocks) proportion correct, hit rate, false alarm rate, d' and criterion for the recognition task. This might mask some of the variability across lure blocks, but it still tests the hypothesis regarding differences in decision characteristics across processing tasks. If one processing task has a considerably different mean for d' or criterion in one of the recognition blocks, then it will skew the overall mean d' or c in that direction.

With regard to recognition memory, survival processing and pleasantness produced greater proportion correct over the dinner party processing task even when controlling for the average relevance of the stimulus. No main effect was found for false alarms, unless the average relevance rating is included in the statistical model. When including relevance ratings in the statistical model, the grasslands photo and dinner party processing tasks produced greater false alarm rates than the pleasantness processing task produced. The ability to discriminate between signal and noise during the recognition task was better in the survival processing and pleasantness processing tasks than the other processing tasks, unless accounting for the average relevance rating. When accounting for the relevance ratings, no differences existed between processing tasks. No significant differences existed between processing tasks with regard to criterion when including and excluding relevance ratings as a covariate in the statistical model. It PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 58 seems that the average relevance rating primarily influences positive responses to recognition decisions in survival processing.

In line with Nairne’s predictions (e.g., Nairne et al., 2008), survival processing produced higher levels of true recall when not controlling for relevance of the material to the encoding task, but this result does not remain when including relevance ratings. In line with Klein’s hypotheses (Klein et al., 2011) regarding the role of planning in the survival processing effect, no differences in false recall existed between planning processing tasks. Further, each planning processing task produced a greater false recall rate than the pleasantness processing task. This is also in line with research on relational processing. Relational processing tends to produce greater false memory than item-specific processing. These effects were small, however. Essentially, the results indicated that I was successful in creating conditions under which the survival processing effect does not exist.

One model of false memory that might explain the effects of relational processing proposes that greater true and false recognition memory results from a reduced ability to discriminate between highly related concepts during the memory retrieval process. In the process of memory retrieval, several distinctive cues would reduce the uncertainty of the numerous cues brought to mind through relational processing. A signal detection measure of discriminability, d'

, provides a numerical estimate of the ability to discriminate between sought information and all other information. A competing decision model that explains the increased levels of true and false recognition memory involves a more liberal criterion for deciding that the information retrieved is the target information. This might occur if there exists some reason to employ a more liberal criterion. Some have suggested that a cognitive bias to avoid death could produce this type of liberal criterion in survival situations. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 59

The signal detection criterion measure provides a numerical estimate of the threshold for recognition responses. If survival processing produces increased true and false recognition through a cognitive bias, then the criterion value should be lower (i.e., more liberal) in the survival processing task than in the other processing tasks. However, if the effect is due to relational processing alone, the criterion should not differ among planning processing tasks.

These models will be further examined in Experiment 2.

Overview of Experiment 2

Experiment 2 was similar to the first experiment. In Experiment 2, I assessed recall and recognition memory for information that was processed in a contextually rich visualization.

Recall that three visualizations involved a planning component, three goals, and a schematically rich scenario. Two of these scenarios were equated on all characteristics except for the salient goals: The grasslands survival context involved a salient survival goal and the grasslands photo trip removed the salience of survival. The third processing task differed from the grasslands scenarios in the environmental context (grasslands versus dinner party), but is presumed to be similar to the grasslands scenarios on other important aspects, such as relational processing, rich schemas, item-specific processing, planning, and visualization. Another control processing task involved processing information about the pleasantness of the stimuli. This processing task differs from the others in that it tends to produce item-specific processing more than relational processing, does not involve survival, grasslands, planning, or contextually rich and cohesive narrative. It is similar to the other processing tasks in that it involves semantic processing.

Studies have consistently found a survival processing effect when comparing to pleasantness processing.

If survival salience is the important characteristic that results in an increase in true and PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 60 false memory during survival processing, then the grasslands survival scenario should produce greater true and false memory than the other three processing tasks. If the survival processing effect is due, instead, to relational processing or planning then the grasslands survival processing task should not produce greater true or false memory than the other contextually rich processing tasks involving planning.

The stimuli used were highly related word lists. These types of lists inherently produce relational processing. Relational processing was induced in two ways: schematically rich scenario and highly related stimuli. Distinctiveness, or item-specific processing, was induced by relevance or pleasantness ratings. The contextual scenarios involve relational processing along the specific contextual domain (e.g., grasslands survival) and the related word stimuli and distinctive or item-specific processing through the relevance ratings. The pleasantness processing task involved only the relational stimuli and distinctiveness processing. If the additional relational processing in the survival processing effect is responsible for the additional true and false memory, then all scenario processing tasks should produce greater of each types of memory than the pleasantness processing task.

PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 61

CHAPTER III: EXPERIMENT 2

Experiment 2 was designed to replicate the results of the first experiment and to examine the impact of different types of information in the recognition environment on recognition memory performance under different information processing conditions. If increased false memory after the survival aspect of the context explains survival processing, then the survival processing task should produce greater false recall and recognition than other processing tasks.

This could occur through a reduced ability to discriminate, in the recall and recognition environments, between target information and noise that might exist if a high degree of relational information is brought to mind as relevant. Another reason why false recall and recognition might be greater in the survival processing task than in other processing tasks is that the former task may use a more liberal criterion for deciding that a piece of information should be considered recognized. Experiment 2 evaluated these potential explanations by manipulating

(within participants) the semantic relatedness between the recognition lures and the to-be- recognized items.

If survival processing uniquely impacts false memory, then the d' and/or criterion values produced by the survival processing task should be smaller than the d' and/or criterion values produced by the other processing tasks. If the false memory model explains the pattern of memory performance results alone, then d' should be lower in the highly related information environment than in the unrelated information environment, but would not differ between encoding processing tasks. Similarly, if the criterion shift hypothesis proposed by Miller (1999) explains the pattern of memory performance results, then the criterion should be a lower value

(i.e., more liberal) in the survival processing task than the other processing tasks.

In Experiment 2, the procedural error was corrected. Specifically, participants were PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 62

presented with the word stimuli from the “ship” list rather than the “mountain” list during the encoding task. Additionally, the repeated lure “leg” was replaced with the appropriate target word “sorrow” in the recognition test. Recognition memory was compared across three blocks, when target items were paired with highly related information, moderately related information, and unrelated information. This was manipulated within participants and processing task was manipulated between participants.

Method

Participants. One hundred fifty five participants completed the study. Participants were recruited from Amazon.com’s Mechanical Turk website. This website advertises human intelligence tasks and allows people to complete those tasks for small incentives. Social science researchers have begun to use the website as a way to collect data for research studies (see

Barger, Behrend, Sharek, & Sinar, 2012; Berinsky, Huber, & Lenz, 2011; Christensen & Glick,

2013; Crump, MacDonnell, Gureckis, 2013). Researchers have identified conditions in which this recruiting and collection method produces results similar to results produced in the lab, even in learning and memory experiments. Simply adding questions that require participants to understand the directions involved in the task has been shown to produce results similar to lab methods in learning and memory studies. Thus, a few additional control questions were added for this purpose. Participants were paid $1.25 in exchange for their participation.

Four participants were not included in the analyses because they did not follow directions. One person was excluded from analyses because of self-reported disability due to brain trauma. The remaining sample consisted of 80 males (52%) and 75 females (48%) between the ages 19 years to 72 years old (M = 35.82, SD = 12.21; Mode = 22 years old). Ten people did PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 63 not report their age. Fifty-seven percent (n = 89) of participants had graduated college or an advanced degree, 21% had only completed high school, and 18% (n = 28) were in college or had completed some college (college freshman n = 2, sophomore n = 9, junior = 11, senior = 4, some college = 2). One person responded “working adult,” one person responded “16+ years,” and two people provided no response.

Most participants self-identified as Caucasian (61%), but the sample was considerably diverse and contained people identifying as Asian/Asian-American/Pacific Islander (24%),

African-American (8%), Hispanic/Latino (3%), and “Other” (3%). Of those participants in the

“other” category, two people identified as Indian, one person identified as Middle Eastern and one person identified as “mixed.”

Participants were randomly assigned to an encoding processing task. Twenty-five percent

(n = 39) were assigned to the Grasslands Photo encoding task, 24.5% (n = 38) were assigned to the Grasslands Survival encoding task, 26% (n = 40) were assigned to the Dinner Party encoding scenario, and 24.5% (n = 38) were assigned to the Pleasantness encoding processing task.

Participants were randomly assigned to the one of two orders of memory task presentation. Forty-nine percent of participants (n = 76) viewed the recall test first and 51% (n =

79) of participants viewed the recognition test first. I recognized, however, that the data for the performance of a given memory task might be contaminated by the prior performance of a different memory task. Thus, I planned to focus the analyses on the data from the first task each participant performed.

Additionally, participants were randomly assigned to one of three versions of the recognition task. (This was an order variable inserted to control for possible order effects in recognition.) Approximately 33% were assigned to each processing task. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 64

Materials and design. The experiment employed a 4 (Processing Task: grasslands- survival-with-planning, grasslands-planning-without-survival, non-grasslands-planning-without- survival, pleasantness) x 3 (lure type: critical, related, unrelated) mixed-factorial design, with processing task as a between-participants variable and lure type as a within-participants variable.

Participants accessed and completed the study online. Ninety five (63%) participants completed the study using Google Chrome, 43 (29%) participants used Mozilla Firefox, nine

(6%) participants used Internet Explorer, and three (2%) participants used Safari browser web browser.

Stimuli. The stimuli remain the same with the exceptions already mentioned. Specifically, the “ship” word list replaced the “mountain” word list in the ratings task and “sorrow” replaced the repeated word “leg” in the recognition task.

Control questions. Several questions that were designed to assess whether participants understood the nature of the tasks involved in the study were added after each set of instructions.

Participants were required to answer these questions correctly before progressing through the study. Additionally, one question assessing the vividness of the visualization in the relevant conditions and one question assessing the ease of rating the stimuli during the encoding task were added. The responses were on a five-point scale (1 = Extremely difficult , 2 = Somewhat difficult, 3 = Neutral, 4 = Somewhat Easy, 4 = Extremely Easy).

Procedure. The procedure remained the same as the first experiment with a couple exceptions. Experiment 2 was conducted completely online and the order of memory task (i.e., recall or recognition) was rotated across participants. Participants were randomly assigned to the order of memory test. Additionally, several questions were added to make sure participants were PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 65 paying attention to the instructions and tasks. Participants could not access the task without first responding correctly to the instructions check questions.

Results

Ease of rating. Ease of rating was positively correlated to proportion correct during the recognition task in the critical lure blocks (r = .52, p = .02), moderately related lure blocks (r =

.58, p < .01), and the unrelated lure blocks (r = .49, p = .03) for the pleasantness processing task, but not the scenario processing tasks. Similarly, ease of rating stimuli in the pleasantness processing task was significantly related to average rating (r = .43, p = .05). Ease of rating stimuli in the pleasantness processing task was positively correlated with average rating of pleasantness items.

Ease of visualization. Ease of visualization of the scenario processing tasks was positively related to ease of rating stimuli (r = .62, p < .001), exact (r = .45, p < .001), phonetic (r

= .43, p = .001), and possible recall (r = .44, p < .001), d' in the moderately related lure block (r

= .05, p = .03), criterion in the critical lure blocks (r = -.36, p < .01), hit rate in the critical lure (r

= .27, p = .04) and moderately related lure (r = .33, p = .01) blocks, and the proportion correct in the moderately related lure block (r = .33, p = .01).

Ratings. A univariate analysis of variance was conducted on the average ratings with processing task as the between-participants variable. Levene’s test indicated that the assumption of equality of variances was violated, F(3, 151) = 11.28, p < .001, A significant main effect of

2 processing task emerged, F(3, 151) = 13.00, p < .001, ηP = .21, observed power > .99. A series of independent samples t-tests confirmed that the grasslands photo processing task (M = 2.63, SD

= .61) produced higher relevance ratings than did the dinner party processing task (M = 2.24, SD PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 66

= .26), t(77) = 2.92, p < .01, d = .83, 95% CI [.12, .65]. The grasslands survival processing task

(M = 2.72, SD = .56) also produced higher relevance ratings than the dinner processing task, t(76) = 3.77, p < .001, d = 1.10, 95% CI [.23, .74]. The pleasantness processing task (M = 2.96,

SD = .23) produced higher ratings of pleasantness than the grasslands photo relevance ratings, t(49.21) = -3.13, p < .01, d = .56, 95% CI [-.54, -.12]. Average ratings were also higher in the pleasantness processing task than in the grasslands survival processing task, t(49.57) = -2.36, p =

.02, d = .56, 95% CI [-.43, -.04]. Finally, average ratings were higher for the pleasantness processing task than for the dinner party processing task, t(52.07) = -7.27, p < .001, d = 2.93,

95% CI [-.92, -.52].

Average ratings were significantly correlated with d' in the unrelated lures blocks (r = -

.26, p = .02), criterion in the moderately related lures block (r = -.34, p = .002), hit rate in the moderately related lure block (r = .25, p < .03), and false alarm rate in the unrelated lure blocks

(r = .23, p = .04). See Figure 9.

Recall. Some participants may not have properly read the directions for the recall task because 23 participants re-typed ten or more words when the recall text box refreshed and cleared their responses after each minute of recall. This could have resulted in fewer overall words produced during recall in Experiment 2. All repeated words were eliminated from analysis. As in Experiment 1, two independent coders categorized the recalled words into one of three categories: exact match, phonetic match, and possible match.

Of the 529 unique recalled words that were not exact matches to the target words, the two coders agreed on 455 of the categorizations (86% agreement). A third coder independently coded the remaining 74 (14%) recalled words that were not exact matches to the targets. In all cases, the third coder agreed with one of the other two coders. The categorization of a word by two PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 67

independent coders determined the final category assignment of the final 74 words.

Correct recall. A series of univariate analyses on the mean number of correctly recalled words was conducted. With regard to correct recall of the exact stimuli, Levene’s test indicated that the assumption of equality of variances was violated, F(3, 72) = 3.30, p < .03. No significant

2 effect of processing task on recall emerged, F(3, 76) = 1.11, p = .22, ηP = .06, observed power

= .38.

With regard to correct recall including phonetic matches to the target stimuli, Levene’s test indicated that the assumption of equality of variances was violated, F(3, 72) = 2.83, p < .05.

2 No significant effect of processing task on recall emerged, F(3, 72) = 1.09, p = .36, ηP = .04, observed power =.28.

With regard to correct recall including possible matches to the target stimuli, no

2 significant effect of processing task on recall emerged, F(3,72) = .81, p = .49, ηP = .03, observed power =.22. No effects were significant when including average rating as a covariate in the statistical model. See Figure 10.

Intrusions. Every critical lure and 11 moderately associated lures were falsely recalled at least once. Similar to the analysis of correct recall, a series of univariate GLM analyses on the mean number of intrusions was conducted.

With regard to the intrusions when only exact matches to the target words were

2 examined, no significant effect of processing task emerged, F(3, 72) = .12, p = .95, ηP = .05, observed power =.07. With regard to the intrusions when phonetic matches to the target words

2 were examined, no significant effect of processing task emerged, F(3, 72) = .36, p = .78, ηP =

.02, observed power =.12. With regard to the intrusions when possible matches to the target words were examined, no significant effect of processing task emerged, F(3, 72) = .57, p = .64, PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 68

2 ηP = .02, observed power =.16. No effects were significant when including average rating as a covariate in the statistical model. See Figure 11.

The recall results remain unchanged when including data from participants who saw the recall task after the recognition task.

Recognition. Similar to the recall analysis, analysis of recognition data was limited to the participants who saw the recognition task first to eliminate the possibility of the recall task contaminating the recognition data. A separate repeated measures GLM analysis was computed for hit rate, false alarm rate, d', criterion, and proportion correct.

The full model for each of these analyses included the recognition word list counterbalancing variable and processing task as between-subjects variables and lure type block as the within-subjects variable. The lure type block variable consisted of three levels: critical lures block, moderately-related lures block, and unrelated lures block. Each level consisted of a subset of target words and the corresponding lures (e.g., critical lures in the critical lure block).

The subset of target words that was presented in the same block of the recognition task as each of the lure types served as the signal distributions for the purposes of analyses. Each lure type served as the corresponding noise distribution. Thus, the words presented in the same recognition block as the critical lures comprised the signal distribution and the critical lures comprised the noise distribution for the signal detection measures.

Hit rate. Box’s test indicated that the assumption of equality of covariances was violated,

F(66, 3923.37) = 1.67, p < .001. Additionally, Mauchly’s test indicated that the assumption of sphericity was violated (χ2(2) = 13.39, p = .001), so the degrees of freedom were corrected using the Greenhouse-Geisser estimates of sphericity (ε = .85). No significant effects were observed.

See Figure 12. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 69

False alarm rate. Mauchly’s test indicated that the assumption of sphericity was violated

(χ2(2) = 18.85, p < .001), so the degrees of freedom were corrected using the Greenhouse-Geisser estimates of sphericity (ε = .81). Additionally, the Levene’s test indicated that the assumption of homogeneity of variances was violated in the unrelated lure block, F(11, 67) = 2.63, p = .007.

The only significant effect was a main effect of lure type, F(1.60, 107.34) = 113.73, p < .001,

2 ηP = .63, observed power > .99. A series of paired-samples t tests confirmed that the false alarm rate was significantly higher in the critical lure block (M = .61, SD = .23) than in the moderately related lure block (M = .31, SD = .23), t(78)= 11.62, p < .001, 95% CI [.24, .34] and the unrelated lure block (M = .26, SD = .23), t(78) = 12.36, p < .001, 95% CI [.29, .40]. Additionally, the false alarm rate was greater in the moderately related lure block than in the unrelated lure block, t(78) = 2.74, p = .007, d = .22, 95% CI [.01, .08]. See Figure 13.

When including the average relevance rating as a covariate in the model, a significant

2 main effect of rating existed, F(1, 74) = 9.84, p = .002, ηP = .12, observed power = .87. A

2 significant main effect of processing task was also present, F(3, 74) = 4.96, p = .003, ηP = .17, observed power = .90. Independent samples t tests confirmed that the grasslands photo {(M =

.43, SD = .09), t(36) = 2.62, p = .01, d = 1.88, 95% CI [.04, .29]} and the dinner party (M = .51,

SD = .09) processing tasks produced significantly higher false alarm rates than did the pleasantness processing task (M = .27, SD = .08), t(39) = 3.84, p < .001, d = 2.82, 95% CI [.11,

.37]. The dinner party processing task produced a significantly higher false alarm rate than did the grasslands survival (M = .38, SD = .08) processing task, t(39) = 2.06, p < .05, d =1.53, 95%

CI [-.25, -.002].

The grasslands survival processing task also produced a greater false alarm rate than the pleasantness processing task, but the difference only neared significance, t(40) = 1.97, p = .056, PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 70

d = 1.38, 95% CI [-.003, .23].

These results are in line with false memory research on DRM lists (e.g., Howe &

Derbish, 2010). False alarm rate is typically higher for words that are highly related to the stimuli learned during the experiment, but substantially lower for information that is not related to the information previously presented.

Proportion correct. Mauchly’s test indicated that the assumption of sphericity was violated (χ2(2) = 7.69, p = .02), so the degrees of freedom were corrected using the Greenhouse-

Geisser estimates of sphericity (ε = .90). A significant main effect of lure type block existed,

2 F(1.80, 243.96) = 120.72, p < .001, ηP = .57, observed power > .99. A series of paired-samples t tests confirmed that the critical lure block (M = .60, SD = .13) produced a lower proportion correct than the moderately related lure block (M = .75, SD = .16), t(78) = -9.96, p < .001, d = -

1.03, 95% CI [-.18, -.12] and the unrelated lure block (M = .77, SD = .15), t(78) = -11.49, p <

.001, d = -1.21, 95% CI [-.19, -.14]. No significant differences existed between the moderately related lure block and the unrelated lure block, t(78) = -1.67, p = .10, 95% CI [-.04, -.004]. See

Figure 14.

Including the average rating as a covariate in the statistical model produced an interaction effect between average rating and lure type that approached significance, F(1.76, 116) = 3.06, p

2 < .06, ηP = .04, observed power > .55.

d'. Mauchly’s test indicated that the assumption of sphericity was violated (χ2(2) = 8.10, p

= .02), so the degrees of freedom were corrected using the Greenhouse-Geisser estimates of sphericity (ε = .90). The only significant effect was the main effect of lure type, F(1.79, 120.32)

2 = 86.34, p < .001, ηP = .56, observed power > .99. A series of paired samples t tests confirmed that d' was significantly lower in the critical lure block (M = .72, SD = .81) than in the PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 71 moderately related lure block (M = 1.68, SD = 1.10), t(78) = -9.34, p < .001, d = -.99, 95% CI [-

1.16, -.75] and the unrelated lure block (M = 1.85, SD = 1.00), t(78) = -11.52, p < .001, d = -1.24,

95% CI [-1.33, -.94]. Additionally, d' was significantly lower in the moderately related lure block than in the unrelated lure block, t(78) = -2.24, p = .03, d = -.16, 95% CI [-.33, -.02]. See

Figure 15.

When including average rating as a covariate in the statistical model, the main effect was qualified by a significant interaction between average rating and lure type, F(1.81, 119.71) =

2 3.85, p < .03, ηP = .06, observed power > .66. Mauchly’s test indicated that the assumption of sphericity was violated (χ2(2) = 7.04, p = .03), so the degrees of freedom were corrected using the Greenhouse-Geisser estimates of sphericity (ε = .91).

These results indicate that processing task did not significantly impact the ability to discriminate between targets and lures in the recognition task, but the degree of relatedness of the lures to the targets impacted the ability to discriminate between them. These results suggest that the increase in false memory observed in the survival processing effect is not due to survival context.

Criterion. Box’s test indicated that the assumption of equality of covariances was violated, F(66, 3923.37) = 1.23, p = .05. Mauchly’s test indicated that the assumption of sphericity was violated (χ2(2) = 14.52, p = .001), so the degrees of freedom were corrected using the Greenhouse-Geisser estimates of sphericity (ε = .83). A significant main effect of lure type

2 existed, F(1.67, 111.91) = 52.05, p < .001, ηP = .44, observed power > .99. A series of paired samples t tests confirmed that criterion was significantly lower in the critical lure blocks (M = -

.69, SD = .62) than in the moderately related lure blocks (M = -.22, SD = .51), t(78) = -9.90, p <

.001, d = 1.60, 95% CI [-.56, -.37] and the unrelated lure blocks (M = -.14, SD = .51), t(78) = - PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 72

8.12, p < .001, d = 1.46, 95% CI [-.67, -.41]. The criterion was not significantly different in the moderately associated lure block than in the unrelated lure block, t(78) = -1.45, p = .15, d = -.16,

95% CI [-.17, .03]. See Figure 16. Including average rating as a covariate in the statistical model did not change these results.

Most of the recognition results remain unchanged when including data from participants who saw the recognition task after the recall task. The only differences were on the measures of hit rate, proportion correct, d', and criterion when including the relevance/pleasantness ratings as a covariate in the model. Specifically, the main effect of lure type on hit rate was no longer significant. Only the effect of rating on hit rate was significant. The interactions of rating and lure type on proportion correct and d' (when including relevance/pleasantness ratings as a covariate) were also not significant when including the participants who saw the recognition task second. Finally, a main effect of relevance rating on criterion was significant.

Summary and Discussion

The results of Experiment 2 indicate that no survival processing effect occurred in true or false recall regardless of whether relevance ratings were accounted for in the statistical model.

With regard to recognition memory, no significant effects on hit rate emerged until relevance ratings were included in the statistical model. This produced a significant lure type (e.g., type of noise distribution) by rating interaction. The critical lure blocks produced significantly greater false alarm rate than the moderately-related and unrelated lure blocks. The moderately-related lure blocks produced a significantly greater false alarm rate than the unrelated lure block. When including relevance ratings as a covariate, all planning processing tasks produced significantly greater false alarm rates than the pleasantness processing task. Additionally, the dinner party produced a significantly greater false alarm rate than the survival processing task. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 73

With regard to proportion correct, the moderately-related and unrelated lure blocks produced a significantly higher proportion of items correctly categorized than the critical lure blocks. However, this was qualified by a relevance by lure type interaction when including the covariate. It was harder to discriminate between target and lures in the critical lure block than in the moderately-related and unrelated lure blocks. It was harder to discriminate in the moderately- related than unrelated lure blocks. However, including the relevance ratings as a covariate in the model produced a lure type by ratings interaction. Finally, the critical lure block produced a more liberal criterion than the moderately-related and unrelated lure blocks. This effect remained the same when including relevance ratings as a covariate in the statistical model.

Contrary to predictions, the survival processing task did not produce greater true or false recall than the other planning processing tasks. This falls in line with Klein’s idea (Klein et al.,

2011) that planning plays a primary role in the pattern of results typically demonstrated under conditions of survival processing. Further, with regard to recognition memory, only the effect of lure type (in the case of criterion) and relevance ratings affected hit rate, proportion correct and d'. The three planning processing tasks produced significantly higher false alarm rates than the pleasantness processing task when controlling for relevance ratings. This falls in line with the idea that greater relational processing produces greater false memory. Additionally, it indicates that the survival processing task did not produce a greater false alarm rate than the non-survival planning tasks, providing weak evidence for Klein’s claim that planning explains the pattern of memory results found under survival processing tasks.

PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 74

CHAPTER IV: GENERAL DISCUSSION

Experiment 1 demonstrated a survival process effect on true recall, and that this effect was driven by perceived congruity. However, there was a planning effect on false recall. That is, the three planning processing tasks produced greater false recall than the pleasantness processing task. This might be due to a greater amount of relational processing, visualization, richness of encoding, or reduced amount of item-specific processing. However, the results of Experiment 2 failed to replicate the recall results. The lack of significant differences in correct recall in

Experiment 1 when controlling for the covariate was replicated in Experiment 2. This might be due to the combination of a small effect size in the first experiment and a reduced sample size in the second experiment. Further data collection to obtain larger sample sizes capable of detecting small effect sizes is suggested. Another possibility is that the nature of the recall task interfered with participants’ reports of recalled stimuli. Specifically, when participants repeated a large amount of words they may not have been engaging in the same mental processes as people who completed the task without repeating a large number of words. The next study should correct the feedback issue on the recall task so that participants can see all the words they entered during the previous minute. This would reduce the number of repeated words.

There was no survival processing effect in hit independent of relevance ratings, but

Experiment 2 demonstrated that hit rate was also affected by the relatedness of the information in the recognition environment. Experiment 2 replicated the planning effect on false alarm rate above the effect of relevance ratings that was demonstrated in Experiment 1. The survival processing task did not produce a greater false alarm rate in the first experiment, but did in the second experiment. Experiment 2 also demonstrated that false alarm rate was affected by the relatedness of the information in the recognition environment. The small survival processing PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 75 effect on proportion correct present in Experiment 1 failed to replicate in Experiment 2. This might be due to the small effect size in Experiment 1 and the reduced sample size in Experiment

2. A larger sample size should be obtained.

Experiment 2 replicated the finding that when controlling for relevance/pleasantness ratings, participants in all groups found it similarly difficult to discriminate between target and lure words on the recognition task. Further, Experiment 2 demonstrated that all groups found it more difficult to discriminate when lures were highly related versus moderately and unrelated.

This was qualified by ratings, as well. This could account for the greater false alarm rate in the critical, moderately-related, and unrelated lure blocks, consecutively. Both experiments demonstrated that all processing tasks produced similar criterion values. However, Experiment 2 demonstrated that participants in all groups used a more liberal criterion when information in the recognition environment was highly related to the target information than when information in the recognition environment was moderately-related or unrelated. This could at least partially account for the greater false recognition rates in the critical lure than moderately-related and unrelated lure blocks. Thus, the d' results support the false memory model and the criterion results support the criterion shift model for the critical lure block only. Further research should attempt to replicate these effects and statistically compare the fit of each model. Notably, the measures of the decision characteristics in recognition memory did not indicate any differences between encoding processing tasks. It is possible that this is due to a reduced sample size that was unable to detect small effects. It might also be due to a particular combination of relational and item-specific processing that occurs in the presence of rich encoding scenarios, highly related word stimuli, and pleasantness processing. Clearly planning alone cannot be the explanation for similar decision characteristics because the pleasantness task was similar on PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 76 these measures to the planning processing tasks. Further research to discern the proximate explanation for these effects is warranted.

The present study was designed to test the idea that processing information in terms of its survival relevance improves memory and to examine different characteristics involved in this phenomenon. The present research was designed to examine whether survival processing produces significantly better memory performance on recall and recognition tasks than similar processing tasks that remove the salient survival aspect but retain a planning component.

Other researchers (i.e., Klein et al, 2010) contend that the survival processing effect can be explained solely by the planning process that is inherent to the typical survival processing instructions. Additionally, other researchers (i.e., Howe & Derbish, 2010) found that survival processing independently increases the likelihood of producing false memories. The present research was designed to examine whether survival processing uniquely contributes to false memory illusions.

In order to examine these ideas, the present study compared the original survival processing instructions to two other planning processing tasks and a common semantic processing task (i.e., pleasantness). One of these planning processing tasks (i.e., grasslands photo processing task) contains the same environmental context as the survival processing scenario without the salient survival aspect. The other planning processing task (i.e., dinner party processing task) removes the grasslands environment, but retained the planning component. This processing task was used in previous research examining the role of planning in the survival processing effect. The pleasantness processing task involved no planning, no environmental context, and no salient survival aspect.

If planning completely explains the survival processing effect, then no differences should PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 77 have been observed among the planning processing tasks, and all planning processing tasks should have produced better memory than the pleasantness processing task. However, if the salient aspect of survival independently improves memory, then the grasslands survival scenario should have produced better memory performance than the other planning processing tasks. The grasslands photo processing task might have included an inherent survival aspect that was less salient. That is, the idea of being alone on a grasslands (regardless of the stated goal while there) might be enough to prime survival, even if it was not specifically mentioned. If this is true, then the grasslands survival scenario should have produced similar memory performance to the grasslands photo scenario, and both should have been superior to the dinner party scenario and the pleasantness processing task.

The present study also extended research on the role of planning in the survival processing effect to recognition memory. Recall that memory performance typically differs between recall and recognition tasks, where recognition tasks typically produce better memory performance. Additionally, the present research examined false memory for information with varying degrees of relatedness to the stimuli. Recall that Howe and Derbish (2010) found that survival processing independently increases the likelihood that false memory would be produced.

Further, they found that false memory was increased when fewer themes were present in the word stimuli. This suggests that false memory is tied to the presence of related information, or relational processing.

The present results do not support the contention that survival processing independently increases false memory. Rather, the false memory observed in the present study can be explained by the false memory model proposed by Wixted and Stretch (2000). That is, the increase in memory performance associated with survival processing is accompanied by an increase in false PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 78 memory. False memory increased similarly across all processing tasks for highly related information more than moderately related information and unrelated information. False memory was not greater for the survival processing task when processing tasks were equated on relational processing. The current study further demonstrates that the false memory effect can be explained by a reduced ability to discriminate between actual memories and highly related information that comes to memory when activated by relational processes involved in the memory search. This was demonstrated through the use of signal detection theory measures. The results of the current study partially support the competing hypothesis that the increase in false memory in survival processing is due to a more liberal cognitive bias than in other types of information processing conditions.

Further, the current research examined the hypothesis that the survival processing effect is distinct from the effects of planning by comparing the survival grasslands scenario to a highly similar scenario (i.e., grasslands photo trip) that removed the salient aspect of survival and maintained the same planning component. These two processing tasks produced similar levels of recall and recognition.

The current research provides evidence that basic memory processes can explain the survival processing effect. Specifically, survival processing has been demonstrated to operate through relational and distinctive processing and congruity effects. Other studies provide evidence for the contention that survival processing involves increased relational and distinctive processing of information. Howe and Derbish (2010) found that the survival processing effects disappeared when relational processing was increased.

The present results imply that the survival salience is not necessary to produce effects on memory performance similar to those previously demonstrated after survival processing. Rather, PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 79

the presence of certain basic memory processes can produce these effects.

It might be more enlightening to view the adaptive process as having shaped these basic memory processes through the requirements of information necessary to interact appropriately in a given environment or hypothetical future contingency rather than through the specific survival content of the environment. The universal problem should not be thought of as a need to remember specific survival-related contextual information, but as a need to store, search, and retrieve relevant information about the environment in a cost effective way so as to be able to successfully interact with it as a way to obtain life necessities. As Todd, Hertwig, and Hoffrage

(2005) state, “...the two main selective pressures acting on memory systems...appear to be, first, to produce quickly the most useful stored information and, second, not to produce too much information” (p. 783). These selective pressures are broad enough to affect many different content-specific domains.

Does the salience of a survival goal or conditions of the EEA uniquely increase the efficiency or likelihood of making a good decision over other specific-content domains? Along with other research (e.g., Klein, 2013), the results of the present studies suggest that the answer is “No.” Instead, the increased ability of one to identify relevant information (e.g., through increased relational processing), to discriminate among instances of possibly relevant information (e.g., through item-specific or distinctiveness processing), and to possibly actively engage that information in preparation for future events (e.g., planning, through the creation of derived memories from inceptive memories), explain the patterns of true and false memory performance typically found during survival processing. These processes can be considered adaptive. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 80

Possible Limitations

Experiment 1 consisted primarily of college students in Washington DC, which might be limited in generalizability at least to American college students, primarily of Caucasian ethnicity.

These students may vary from the population at large because they tend to be particularly affluent as compared to the rest of the world, and most grew up in the United States. These results are in line with other studies that have used different samples, which suggests that the effect is not limited to the participants of this sample. In the second experiment, a more heterogenous sample was used. The demographic characteristics from the mTurk sample were more representative and diverse than typical convenience samples, though still limited to mostly

Caucasian Americans.

Another limitation of the current studies is that participants were given incentives of class credit or $1.25. People who participate in online research for low wages might be different from people in the population who do not participate in research or do not participate in research for low incentives. One difference might be the type of job or education the participants have.

Memory processes are generally considered to be universal, but there may be additional variability associated with other variables that strongly relate to socioeconomic status such as nutrition and brain health.

The stimuli in these experiments consisted of lists of words. This type of stimulus might not be ideal because word lists may be limited in the rich contextual information that people experience in everyday settings outside of the laboratory. That is, the stimuli might seem artificial and lack external validity. However, the use of highly related word lists reduces this concern slightly because people typically encode information by elaborating on the information and connecting it to other related information. The stimuli have construct validity.

Additionally, numerous other studies have examined the survival processing effect using PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 81 other stimuli, such as pictures, that might be more similar to everyday experiences. Other stimuli, including unrelated word lists, word lists that are controlled on more characteristics of the words

(e.g., frequency, familiarity, word length, etc.) might also be used in future studies to see if the survival processing effect reappears.

While the results of the current research indicated statistically significant differences with regard to some dependent variables, the practical effects of these differences are worth consideration. A distinction can be made between statistically significant and practically significant effects. Statistics are sensitive to sample size and even a very small statistically significant effect can be detected given a large enough sample. An important question is whether the significant results make any difference when making practical interpretations of the data. The current research involved a carefully controlled, artificial laboratory environment. The environment outside of the laboratory is likely more varied, rich, and involves actual experiences. It is difficult to know how the effect sizes of the laboratory study generalize to the natural environment.

Another possible limitation is that the recognition test consisted only of 90 items, which resulted in several participants getting very high proportion correct and hit rates. Though proportion correct never reached ceiling, hit rate did. Ceiling effects could reduce variability of higher performing participants, which would reduce the confidence in the measures of central tendency in those conditions that had ceiling effects. This limits the conclusions that can be drawn about the differences between processing tasks.

Participants in Experiment 2 completed the study online. As such, the strict controls that are desirable in purely experimental studies were reduced. Participants who completed the study online might not have attended to the study as did participants in the lab. The inability to control PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 82 for distractions and external influences on the variables in this study could be problematic.

However, research has found that learning and memory data collected from Amazon.com’s

Mechanical Turk is similar to that collected in the lab when questions are included to ensure participants understood the task and were paying attention (Buhrmester, Kwang, & Gosling,

2011). This study employed several attention and instructions check questions. The constant rotation through different sorts of tasks likely kept participants engaged. In fact, some participants were so engaged that they reported feeling affected by the fact that most of the words were not relevant to their visualization.

PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 83

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PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 94

APPENDIX A: RATINGS STIMULI

Positive Critical Lures Neutral Critical Lures Negative Critical Lures

Party Leg Sad weekend hip despair festival cramp unhappy surprise crutch frown slumber limp happiness decoration thigh happy celebration arm sorrow birthday ankle depression celebrate calf lonely host knee blues costume limb grief (M = .29) (M = .26) (M = .35)

Funny Same Bad clown similar awful comedy opposite villain ridiculous alike sin serious identical worse silly different unpleasant wit usual nasty amuse differ attitude hilarious difference good humor routine terrible comedian dissimilar mischief (M = .33) (M = .31) (M = .28)

Air Deer Death vent stag suicide breath antler life breathe elk widow atmosphere doe grave pollution buck murder oxygen ewe casket plane gazelle cemetery conditioner moose funeral balloon hunting tragedy PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 95

fan antelope burial (M = .27) (M = .28) (M = .30)

Water Paper Sick dam fold hospital raft tissue virus drip margin nausea lake paperclip fever swim document healthy boil thesis medicine flood sheet flu stream folder throw up surf pad disease mineral staple well (M = .33) (M = .32) (M = .31)

Fruit Ship* Hurt kiwi vessel offend citrus ahoy ouch produce sailor pain vegetables anchor punish cherry port injury berry cruise bruise plum pirate sore strawberry viking pinch pear crew harm raspberry captain wound (M = .31) (M = .27) (M = .34)

Mountain* hiker hiking valley hike climber climb cliff peak hill summit (M = .26) *Due to a procedural error in Experiment 1, the words from the list created from the positive critical lure “mountain” were presented during the ratings task instead of the words from the list PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 96 created from the neutral critical lure “ ship”. However, the words from the “ship” list were presented during the recognition task instead of the target words from the “mountain” list. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 97

APPENDIX B: RECOGNITION TASK STIMULI

Lures

Critical Lures Moderately Associated Lures Unrelated Lures party veer crowd funny scroll mimic air depth glide water remorse foam fruit feelings seed sad navigator** gray bad appendage hate death pump black sick rotten wart hurt joke hamper same monotonous double paper apple fling ship** tomb build** leg* gathering stump deer vomit shooting

Targets

Subset A Subset B Subset C berry birthday arm casket boil blues crutch ewe breath decoration fan citrus despair happy document fever hospital funeral flood leg* humor hilarious pain mineral hunting plum mischief margin sailor** moose offend serious port** opposite similar slumber unpleasant tissue throw up vent villain usual vessel** widow wound

*Due to an error in the procedure of Experiment 1, the word “leg” was displayed twice to all participants during the recognition task, once as a target word and once as a critical lure. **Due to an error in the procedure of Experiment 1, items from the word list created from the PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 98 neutral critical lure “ship” were not presented during the encoding stage. Thus, they were removed from analysis of the recognition task.

PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 99

APPENDIX C: NARRATIVE DESCRIPTIONS OF PROCESSING TASKS

Grasslands photography

“I came out from a sort of forest to see open grass area with two large hills in the distance. I saw an antelope running across the plains in the distance, so I went closer to take a picture of him, other deer and such animals were prancing in a valley not too far away.”

“I thought about an open meadow filled with heavy vegetation. Wildlife such as large and small animals ate from the vegetation. Behind the animals and the meadow was a tall hill covered in trees in front of a bright clear blue sky. I was setting up my photography equipment using some disguises behind some trees. The goal of the shot was to get the animals in the most natural environment without intruding on their own space so I remained in the trees while the animals were in the clearing.”

“I imagined a bright sunny day so that lighting would not be a factor in planning. Also i made sure to have a water proof camera so that when I was taking pictures near water I wouldnt risk getting it wet. I imagined an area with savannah land, with a small mountain and hill. Animals around were mostly prey animals. I considered safety measures to keep from being bit by small animals in the tall grass. I imagined being alone, and it being a very hot day.”

Grasslands survival

“i thought about Africa. The plains, mountaind, river lakes, tall grasses, blright blue skies. Leopards in trees, cheetahs on mounds of dirt, prides of lions hunting. Elephants in forest. hiking up mountains. going to rivers and seeeing hippos and crocodiles fighting. seeing flooding and dry areas.having a guide drive me around and sleeping in tents. Being wary of dangerous snakes and of malaria.Going to lakes and fishing. walking very far and taking pictures at night with night vision.”

“I thought about being alone on a plain in the middle of nowhere with no buildings around. I imagined being surrounded with wild beasts and dangerous environments in which it was cold and i was naked with nothing to provide sustance for myself. I imagined sleeping in the hopeless environment in a bed of grass near a hill so i could have relief from the ever striking wind and hearing noices all night with nothing to defend myself with. I further thought about getting hurt by one of these wild animals with nothing to santitize it and nothing to protect me from diseases. It was terrifying and all i wanted was to go back home where it was warm.” PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 100

“i saw myself mildly emacipated, mostly thinking about thefirst time i would be hungry enough to kill and prepare an animal. Not that i am particularly squimish, but i feel like that would be the first time the scenarior would feel real to me so that is what i focused on. I thought about how i would try to find a safe place near water and hopefully some berry bushes or fruit trees, but how that wouldnt actually sustain me. I thought about how i would try and hunt and defend myself. Thought about trying to learn how to hunt with a simple sling and rocks i could find anywhere, and trying to sharpen a tree limb into a sort of spear or steak to wedge against the ground should a predator try and go after me.”

Dinner Party

“I imagine that I walk through a market where I usually go in my hometown and I picture all the foods and things I want to buy and think about whether my guests will like it or not in general. Then I think about what will the guest look like and what is their relationship with me and pictues the scene that I open the door for them and greet each other.”

“I was planning a funny costume party for someone's birthday. I remember walking in the store and looking for food that would work for everyone, regardless of most dietary restrictions, and deciding fruit was a safe bet. I can also remember getting fruit punch and streamers, but I spent the most time thinking about what foods would be best.”

“I thought about all of the food spread out on the table, desserts, appetizers, and the main meal. I started first listing off the foods I know that I wanted to bet there like pasta, mozzarella sticks and eclair cake. Then I though well I do not want to offend anyone by not having more food so I'll have food of all types. So I though of chinese food, italian food, and american food. I'd have it all. Then I realized oh wait I need appetizers, that is where the mozzarella sticks can go! I'll have a vegetable tray and crackers and such. I'll need drinks too all different kinds. Oh and can't forget about dessert I'll need eclair cake and cookies and Pumpkin cake. I hope everyone has a good time I think they will because I'll have so much food. This is going to be a lot of work cooking and shopping for all of this not to mention horrendously expensive. They all better like it if I am spending this much money.”

PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 101

APPENDIX D: EXPERIMENT 1 HSRB-APPROVED CONSENT LETTER PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 102 PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 103

APPENDIX E: EXPERIMENT 2 HSRB-APPROVED CONSENT LETTER PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 104

PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 105

Table 1 Established Influences on Memory Performance

Construct Description Further Reading

Organization Concepts are directly and indirectly associated with other Anderson & concepts to form an associative network. Bower, 2013 Elaboration The process of relating newly acquired information to other Meyers-Levy, pieces of information already in memory during encoding. 1991

Relational processing can be considered a type of elaboration where information about the similarity of one element in a particular context is extended to other elements within that context, creating strong associations between concepts with similar elements that will aid in retrieval. Semantic The tendency for highly related words to be retrieved and Collins & Loftus, relatedness judged faster than unrelated words. 1975 Encoding Information is encoded into a rich memory representation Tulving & specificity that includes the context during the encoding process. Thomson, 1973 Schemata Overarching cognitive structures of knowledge acquired Alba & Hasher, through experience and used to aid in organizing and 1983; Bower, retrieving information from memory. Retention of new 2000; Roediger information is better when it is congruent than when it is & McDermott, incongruent with one’s schema. 1995 Self-reference The self acts as an organized structure of information about Klein, 2012 the world that facilitates elaboration and organization of new information that is related to oneself. The self has been referred to as somewhat of a “super schema.” Distinctiveness The processing of non-overlapping attributes or the Burns, 2006 encoding of item-specific cues in the presence of relational cues produces better memory performance, probably by increasing discriminability during memory retrieval. Congruity The congruity effect refers to better memory when the Craik & Tulving, encoding task uses orienting questions that elicit a “yes” 1975; Schulman, rather than “no” response. 1974 Planning Planning for the future is a necessary component of human Klein, cognitive architecture and works interdependently with Robertson, & memory systems. Information from memory processes is Delton, 2010 PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 106 used to make decisions about current and future events. Long-term memory processes allow people to use information from previous experiences to make decisions and plan about current or future behavior.

PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 107

Table 2 Experiment 1 Means and Standard Deviations of Recall and Recognition Measures Dependent Grasslands Grasslands Dinner Variable Photo Survival Party Pleasantness Total

Recall n = 58 n = 56 n = 57 n = 58 n = 229

Exact Correct 25.24 29.23 22.09 26.84 25.84 (10.32) (9.57) (8.11) (9.79) (9.77)

Phonetic Correct 25.59 29.89 22.79 27.36 26.39 (10.42) (9.56) (8.12) (9.75) (9.79)

Possible Correct 26.29 30.80 23.70 27.90 27.16 (10.40) (9.52) (8.48) (9.82) (9.86)

Exact Intrusion 3.95 5.27 4.40 2.74 ( 4.08 (3.44) (4.49) (2.72) 2.01) (3.39)

Phonetic 3.60 4.61 3.70 2.22 3.52 Intrusion (3.28) (4.36) (2.66) (1.83) (3.25)

Possible 2.90 3.70 2.79 1.69 2.76 Intrusion (3.04) (4.12) (2.42) (1.51) (2.99)

Recognition n = 48 n = 44 n = 43 n = 44 n = 179

Hit Rate .88 .91 .88 .92 .90 (.08) (.08) (.09) (.05) (.08)

False Alarm .27 .23 .26 .21 .24 Rate (.14) (.13) (.12) (.13) (.13)

d prime 1.98 2.27 1.97 2.46 2.17 (.69) (.63) (.50) (.69) (.66)

Criterion -.30 -.32 -.31 -.31 -3.12 (.29) (.38) (.37) (.31) (.34)

Proportion .81 .84 .81 .86 .83 Correct (.09) (.07) (.06) (.08) (.08)

PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 108

Table 3 Experiment 2 Means and Standard Deviations of Recall and Recognition Measures Dependent Grasslands Grasslands Dinner Variable Photo Survival Party Pleasantness Total

Recall n = 22 n = 17 n = 20 n = 17 n = 76

Correct

Exact Correct 15.05 15.29 11.05 15.35 14.12 (7.33) (6.49) (5.62) (10.25) (7.61)

Phonetic 15.45 15.47 11.90 15.71 14.58 Correct (7.79) (6.40) (6.02) (10.26) (7.75)

Possible 16.00 16.35 12.85 16.06 15.26 Correct (7.98) (6.75) (7.09) (10.27) (8.06)

Intrusions

Exact 5.77 5.71 5.00 5.24 5.43 Intrusion (4.81) (3.90) (3.63) (6.34) (4.66)

Phonetic 5.36 5.53 4.15 4.88 4.97 Intrusion (4.55) (3.91) (3.25) (6.13) (6.15)

Possible 4.82 4.65 3.20 4.53 4.29 Intrusion (4.65) (3.55) (3.07) (5.88) (4.35)

Recognition n = 17 n = 21 n = 20 n = 21 n = 79

Hit Rate

Critical Lure .82 .75 .85 .85 .82 Block (.19) (.28) (.20) (.13) .21)

Moderately .87 .75 .80 .86 .82 Related Lure (.11) (.27) (.17) (.15) (.19) Block

Unrelated .82 .78 .86 .84 .82 Lure Block (.16) (.16) (.17) (.14) (.15)

False Alarm Rate

Critical Lure .69 .61 .65 .50 .61 Block (.19) (.24) (.22) (.22) (.23) PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 109

Moderately .33 .31 .38 .23 .31 Related Lure (.27) (.22) (.27) (.21) (.24) Block

Unrelated .33 .27 .30 .17 .26 Lure Block (.26) (.23) (.27) (.13) (.13)

d prime

Critical Lure .49 .47 .72 1.17 .72 Block (.66) (.79) (.81) (.76) (.80)

Moderately 1.79 1.45 1.37 2.11 1.68 Related Lure (1.00) (1.13) (1.10) (1.08) (1.10) Block

Unrelated 1.58 1.69 1.93 2.17 1.85 Lure Block (.79) (1.02) (1.18) (.90) (1.00)

Criterion

Critical Lure -.83 -.55 -.82 -.57 -.69 Block (.60) (.77) (.61) (.45) (.62)

Moderately -.35 -.12 -.26 -.16 -.22 Related Lure (.48) (.64) (.50) (.38) (.51) Block

Unrelated -.24 -.05 -.27 -.03 -.14 Lure Block (.63) (.48) (.50) (.34) (.51)

Proportion Correct

Critical Lure .59 .53 .62 .67 .60 Block (.12) (.11) (.12) (.14) (.13)

Moderately .79 .69 .74 (.15) .80 .75 Related Lure (.13) (.18) (.14) (.16) Block

Unrelated .76 .72 .79 .82 .77 Lure Block (.11) (.16) (.17) (.12) (.15)

PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 110

Figure 1 Experiment 1 mean relevance/pleasantness ratings.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 111

Figure 2 Experiment 1 mean number of words correctly recalled.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 112

Figure 3 Experiment 1 mean number of words falsely recalled.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 113

Figure 4 Experiment 1 hit rate in recognition memory.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 114

Figure 5 Experiment 1 false alarm rate in recognition memory.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 115

Figure 6 Experiment 1 mean proportion of recognition items correctly categorized.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 116

Figure 7 Experiment 1 mean d'.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 117

Figure 8 Experiment 1 mean criterion.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 118

Figure 9 Experiment 2 mean relevance/pleasantness ratings.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 119

Figure 10 Experiment 2 mean number of words correctly recalled.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 120

Figure 11 Experiment 2 mean number of words falsely recalled.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 121

Figure 12 Experiment 2 hit rate in recognition memory.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 122

Figure 13 Experiment 2 false alarm rate in recognition memory.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 123

Figure 14 Experiment 2 mean proportion of recognition items correctly categorized.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 124

Figure 15 Experiment 2 mean d'.

Error bars indicate 95% confidence intervals. PROXIMATE MECHANISMS OF ADAPTIVE MEMORY 125

Figure 16. Experiment 2 mean criterion.

Error bars indicate 95% confidence intervals.