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Unconscious

J F Kihlstrom, University of California, Berkeley, CA, USA

ã 2009 Elsevier Inc. All rights reserved.

Glossary Inattentional blindness – Failure to

consciously perceive an object in the visual Automaticity – The label given to cognitive field because one’s attention is directed and other mental operations that are elsewhere. In various forms of ‘attentional executed outside phenomenal blindness,’ such as repetition blindness, the and voluntary control. Automatic processes attentional blink, and change blindness, contrast with controlled processes in terms of the subject fails to perceive an object (or a four canonical features: they are inevitably change in an object) despite the fact that evoked by the presence of a particular attention is properly directed to the stimulus; incorrigibly executed, in a ballistic appropriate portion of the visual field. fashion, once evoked; effortless, meaning – A relatively permanent change in that they consume little or no cognitive which occurs as a result of capacity; and efficient, in that they create little experience. ‘Explicit learning’ covers cases or no interference with other cognitive where the subject is consciously aware of this activities. new knowledge. ‘’ refers to Conscious shyness – The resistance of any effect of acquired knowledge affects and other cognitive sciences to experience, thought, or action in the absence making a focus of inquiry. As of conscious awareness of what has been described by Owen Flanagan, conscious learned. shyness has four facets: ‘positivistic reserve,’ Limen – In classical , the or a preference for publicly verifiable ‘threshold,’ or minimum amount of stimulus behavioral data over introspective self-reports; energy needed for an observer to ‘piecemeal approach,’ the assumption that an consciously detect the presence of, or understanding of consciousness will emerge change in, a stimulus. In ‘subliminal from more narrowly defined studies of ’ the stimulus is too weak to be perception, , and the like; ‘conscious consciously perceived, or has been inessentialism,’ the view that consciousness is degraded by virtue of brief presentation, not necessary for certain cognitive functions, a masking stimulus, or the deployment of such as perceiving and remembering; and attention elsewhere. ‘epiphenomenalism,’ the view that consciousness plays no causal role in Memory – The mental representation of mentallife. some past event. ‘Explicit memory’ entails conscious recollection of some past event, as Dissociation – An experimental outcome in which one independent variable, such as in or recognition. ‘’ refers to any effect on experience, thought, or brain damage, has different (e.g., opposite) effects on two or more dependent variables. action of a past event, in the absence of Many studies of conscious recollection of that event. indicate that some variable (such as brain Perception – The mental representation of damage or the direction of attention) an event in the current stimulus environment, or that of the very recent past. ‘Explicit dissociates, or has different effects on, explicit and implicit expressions of perception’ is indicated by the observer’s perception, memory, and the like. conscious awareness of the size, shape,

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Unconscious Cognition distance, motion, and identity of some

stimulus. ‘Implicit perception’ refers to any As psychology developed as an empirical science, effect on experience, thought, or action of theory and research focused on those mental such an event, in the absence of conscious states that were accessible to consciousness, as perception of that event. represented by classical psychophysics (with its Preattentive processes – Perceptual and interest in sensory thresholds), the structuralists’ cognitive operations that occur before method of introspection, and ’ clas- attention has been paid to a stimulus. sic essay, in the Principles of Psychology, on the Priming – The facilitation (or impairment) of stream of consciousness. Following the onslaught processing of a stimulus (the target) by prior of radical , interest in consciousness presentation of another stimulus (the prime). declined precipitously in the years after World In ‘repetition priming,’ the prime physically War I. Woodworth’s work on the span of appre- resembles the target; in ‘semantic priming,’ hension was an exception, and consciousness was the prime and target are related in terms of the subtext of the Gestalt approach to perception. meaning. But serious scientific interest in consciousness had Process-dissociation procedure – to await the cognitive revolution, with its interest A method, invented by Jacoby, for in attention, short-term memory, and mental imag- quantifying the contributions of automatic ery. The widespread current interest in conscious- and controlled processes to task ness is illustrated by the very existence of performance by pitting the one against the encyclopedias like the present one. other. In the ‘Inclusion’ condition, automatic Even in the nineteenth century, however, psy- and controlled processes are allowed to work chologists recognized that the mental structures in the same direction; in the ‘Exclusion’ and processes underlying experience, thought, condition, automatic processes are placed in and action were not completely encompassed opposition to controlled processes. within the span of conscious awareness. Herbart’s Thought – As a verb, thinking refers to ‘limen’ made room for Leibniz’s ‘petites ,’ various cognitive operations, such as and of course Helmholtz argued that conscious reasoning, problem-solving, judgment, and perception was based on unconscious inferences. decision-making. As a noun, thought refers to Perhaps the most forceful advocate of noncon- any mental representation, such as the idea scious mental life was William James, who (again or an image of a thing, which is itself neither a in the Principles) held that mental states could be percept (a mental representation of a unconscious in at least two different senses. First, a stimulus in the current environment) nor a mental event can be deliberately excluded from memory (a mental representation of a past attention or consciousness: ‘‘We can neglect to stimulus). attend to that which we nevertheless feel’’ (p. 201). Unconscious inference – As described by These unattended, unconscious thoughts and feel- Helmholtz, the inferences or thought ings are themselves mental states. Second, and processes that, automatically and more important, James drew on clinical observa- unconsciously, generate conscious tions of cases of hysteria and multiple personality perception from stimulus information. For to argue for a division of consciousness into pri- example, perceivers unconsciously apply the mary and secondary (and, for that matter, tertiary size–distance rule to take information about and more) consciousnesses (sic), only one of which size into account when judging the distance is accessible to phenomenal awareness at any point of an object, and vice-versa, to create the in time. To avoid possible oxymoron in the nega- ‘moon illusion’ and other perceptual effects. tion of consciousness, James preferred to speak of ‘co-conscious’ or ‘subconscious’ mental states,

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rather than ‘unconscious’ ones. There, was, in fact, make it past the filter was not. This same atten- considerable interest in unconscious mental life in tional filter was also the threshold which had to be the early twentieth century – even setting aside the crossed for information to be represented in phe- work of . But, as with conscious- nomenal awareness. The filter theories of attention, ness, the entire topic was banished from serious in turn, raised questions about how permeable the discourse by behaviorism. attentional filter was, and how much information History repeated itself in the latter half of the processing could occur preattentively. Was preat- twentieth century, as the ‘consciousness revolu- tentive – preconscious – processing limited to ele- tion’ which followed on the cognitive revolution mentary physical features of the stimulus, or could spun off an interest in unconscious mental life as it extend to the meaning of the stimulus as well? well. This happened slowly. For a long time, if the In part to solve these problems, the notion of an unconscious was discussed at all, it was construed attentional filter was replaced by the notion of merely as a repository for unattended percepts attentional capacity. Capacity theories, such as and forgotten . But in addition to this the one proposed by Kahneman in the early wastebasket view of the unconscious, the classic 1970s, began with the assumption that human multistore model of information processing made information-processing capacity is limited, and room for the unconscious by identifying uncon- proposed that the ability to perform one or more scious mental life with early, ‘preattentive’ mental task(s) depended both on the resources available processes that occur prior to the formation of and the resources required by the task(s) them- a mental representation of an event in primary selves. Whereas the filter models conceived of infor- memory. However, by implicitly identifying con- mation processing as serial in nature, the capacity sciousness with ‘higher’ mental processes, the models implied that several tasks could be carried classic multistore model left little or no room out simultaneously, so long as their attentional for a more interesting view of the ‘psychological requirements did not exceed available resources. unconscious’ – complex mental structures and The capacity view, in turn, led in the mid-1970s processes, and full-fledged mental states, that influ- to a distinction between two types of cognitive ence experience, thought, and action, but which are processes, ‘controlled’ and ‘automatic.’ Controlled nevertheless inaccessible to phenomenal awareness, processes are conscious, deliberate, and consume insusceptible to voluntary control, or both. cognitive capacity – they are what most people

The rediscovery of the unconscious by modern mean by cognition. By contrast, automatic pro- scientific psychology began with comparisons cesses are more involuntary. That is, they are between automatic and effortful mental processes ‘inevitably evoked’ by the presentation of specific and between explicit and implicit memory. Since stimulus inputs, regardless of any intention on the then, it has continued with the extension of the part of the subject. And once evoked by an effective explicit–implicit distinction into the domains of environmental stimulus, they are ‘incorrigibly exe- perception, learning, and thought. Taken together, cuted,’ in a ballistic fashion. Automatic processes this literature describes the ‘cognitive unconscious.’ are ‘effortless,’ in that they consume little or no

attentional capacity. And they are ‘efficient,’ in that they do not interfere with other ongoing mental

Attention, Automaticity, and activities. Perhaps because they are fast, or perhaps Unconscious Processing because they do not consume cognitive capacity, automatic processes are unconscious in the strict

The earliest information-processing theories of sense that they are inaccessible to phenomenal attention, such as those proposed in the 1950s by awareness under any circumstances, and can be

Broadbent and others, were based, to one degree or known only by inference. another, on the metaphor of the filter. Information Automatic processes are exemplified by the which made it past the filter was available for Stroop color-word task, in which subjects must ‘higher’ information-processing activities, such as name the color of ink in which words are printed: semantic analysis, while information which did not Subjects show a great deal of interference when the

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word names a color that is different from that in certain judgments made about it, or cannot control which the word is printed. Apparently, subjects their response to it. The further possibility, that simply cannot help reading the words. Helmholtz’s cognitive processes can operate on mental states – unconscious inferences may be viewed, in retro- percepts, memories, and the like – that are not spect, as an early foreshadowing of the concept themselves accessible to conscious awareness, was of automaticity. More recently, linguists such as first raised in modern psychology by observations Chomsky have argued that the universal grammar of priming in neurological patients with the ‘amne- that underlies our ability to use language operates sic syndrome’ resulting from bilateral damage to unconsciously and automatically. the medial temporal lobe, including the hippo- Over subsequent decades, the concept of auto- campus. These patients could not remember maticity has evolved further. For example, some words that they had just studied, but nevertheless theorists proposed that automatic processes have showed normal levels of priming on tasks such as properties other than the four canonical ones out- word-fragment completion and stem completion. lined above. Others have suggested that the fea- On the basis of results such as these, Schacter tures represent continuous dimensions, so that drew a distinction between explicit memory, which processes can be more or less automatic in nature. involves the conscious recollection of some past There has been some question as to whether all the event, and implicit memory, which is revealed by canonical features must be present to identify a any change in task performance that is attributable process as automatic: the four canonical features to that event. Explicit memory, in this view, is might comprise a kind of prototype of automatic- identified with the typical sorts of memory tasks, ity, rather than being singly necessary and jointly such as recall or recognition. Following Schacter, sufficient to define a process as automatic. Even we may define implicit memory formally as the the automaticity of the Stroop effect has been effect of a past event on the subject’s ongoing cast into doubt. Challenges to capacity theory, experience, thought, and action, in the absence from which the earliest ideas about automaticity of, or independent of, conscious recollection of emerged, have led to alternative theoretical concep- that event. Implicit memory is, in these terms, tualizations in terms of memory rather than atten- unconscious memory. tion. Nevertheless, the concept of automaticity has Spared priming has also been observed in various gained a firm foothold in the literature of cognitive other forms of , including the anterograde psychology, and investigators have sought to develop and retrograde amnesia associated with electro- methods, such as Jacoby’s ‘process-dissociation pro- convulsive therapy for depression; the anterograde cedure,’ to distinguish between the automatic and amnesia produced by general anesthesia adminis- controlled contributions to task performance. tered to surgical patients, as well as that associated with conscious sedation in outpatient surgery;

memory disorders observed in dementia, including Implicit Memory Alzheimer’s disease, as well as those encountered in normal aging; hypnotic and posthypnotic amnesia

While automatic processes may be considered to following appropriate suggestions to hypnotizable be unconscious, the mental contents on which subjects; and the ‘functional’ or ‘psychogenic’ amne- they operate, and which they in turn generate, sias encountered in genuine cases of dissociative are ordinarily thought to be available to conscious disorder, including dissociative amnesia, dissocia- tive fugue, and the interpersonality amnesia of dis- awareness – just as Helmholtz’s unconscious infer- ences took consciously accessible stimulus infor- sociative identity disorder (also known as multiple mation and operated unconsciously to generate personality disorder). In each of these cases, the the conscious perception of distance and size. memory disorder primarily impairs explicit mem- Thus, we generally assume that people notice ory and spares implicit memory, which is either and can describe the salient features of an object wholly or relatively intact. It is in this sense that or event, even if they cannot articulate the way in implicit memory can be observed in the absence of which those features have been integrated to form explicit memory.

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However, implicit memory can be observed in brain-damaged patients, while single-systems the- individuals with normal memory functions as well. ories have been developed in the context of data

For example, normal subjects show significant sav- collected from neurologically intact subjects. ings in relearning for items that they can neither Activation theories seem to imply that priming recall nor recognize. In principle, such phenomena cannot occur for novel materials, for which sub- as proactive and retroactive inhibition might also jects have no pre-existing mental representations be expressions of implicit memory, if the interfer- to activate. Priming can occur for novel materials, ence occurred in the absence of conscious recol- in apparent contradiction to the activation view; lection for the interfering list. For the most part, but priming is greatest for novel materials that are however, documented dissociations between composed of familiar elements, lending support explicit and implicit memory in individuals with to the activation view after all. normal memory function take the form of experi- Despite this theoretical controversy, the essen- mental dissociations, in which some variable is tial concept of implicit memory, including its dis- shown to affect explicit but not implicit memory, sociation from explicit memory, is now widely or vice-versa. For example, depth of processing has accepted within . The theo- a substantial effect on explicit memory, but rela- retical debate is likely to persist until investigators in tively little impact on many priming effects. Even the field recognize that most subsequent research when explicit memory is not impaired, implicit on implicit memory, whether in neurologically imp- memory may be said to be independent of explicit aired patients or intact subjects, has been dominated memory, in that priming does not depend on by studies of repetition priming effects of the sort whetherthe prime is consciously remembered. observed in lexical decision, perceptual identifica- Thenatureofimplicitmemoryisthesubjectof tion, stem-completion, and fragment-completion continuing theoretical controversy. The earliest tasks. However, there is more to priming than repe- view was that priming reflected the activation, tition priming. Semantic and conceptual priming throughperceptionanda ttention, of stimulus- effects can also be observed in amnesia, as on free relevant knowledge already stored in memory. association and category generation tasks. These More recently, under the influence of the doctrine priming effects require some analysis of the meaning of modularity in , explicit and of the stimulus, going beyond mere physical struc- implicit memory have been attributed to the opera- ture. Understanding the nature of implicit memory, tion of separate and independent (thus dissociable) when it is spared and when it is impaired, and the memory systems in the brain – or, alternatively, to relations between implicit and explicit memory, brain systems dedicated toperception,action,and requires research on these other expressions of conceptual analysis that have the capacity to learn. unconscious memory. Other theories hold that explicit and implicit mem- ory are the products of a single memory system, but differ in terms of the processes that are deployed at the time of encoding and retrieval. For example, Implicit Learning many priming tasks are held to be perceptually driven, while recall and recognition is concep- Closely related to implicit memory is the concept tually driven. Alternatively, priming may occur of ‘implicit learning’ – a term introduced to psy- automatically, while recall and recognition require chological discourse by Reber’s pioneering experi- conscious effort in retrieval. Along these lines, some ments on artificial-grammar learning. In these theorists have redefined implicit memory as invol- experiments, subjects first studied a set of letter untary memory, thus making conscious control strings which had been generated by an artificial rather than conscious awareness, the defining fea- grammar. Later, they were asked to examine a new ture of the phenomenon. set of letter strings, and identify those that con- formed to the grammar. They were able to do so at The various theories have proved hard to test against each other. By and large, multiple-memory better than chance levels, suggesting that they had systems theories have emerged from studies of induced the grammatical rule from the study set.

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Nevertheless, Reber reported that the subjects learning reflects unconscious knowledge, just as were not able to describe the grammar itself. implicit memory reflects unconscious memory.

In a paradigm somewhat similar to artificial Whether implicit learning can be dissociated grammar learning, subjects have learned to iden- from explicit learning remains an open question. tify instances of novel concepts, such as patterns of The fact that subjects cannot articulate the Markov dots that vary around a prototype, without being process by which grammatical strings were gener- able to describe the defining or characteristic fea- ated does not mean that they are unaware of what tures of the concepts themselves. They can also they have learned. Above-chance classification per- detect the covariation between two features, such formance could well result from partial knowledge as hair length and personality, even though they which is consciously accessible. The same argument cannot identify the basis for their predictions. holds true for other paradigms in which implicit They can learn the sequence in which certain learning has been ostensibly demonstrated. The stimuli will occur, without being able to specify best that can be said, for now, is that the subjects the sequence itself. And they can learn to control in artificial grammar and experi- the output of a complex system by manipulating ments often experience themselves as behaving ran- an input variable, without being able to specify the domly, without an awareness of what they are doing. relationship between the two. In each case, subjects However, this assumption rests on relatively infor- appearto have acquired new knowledge through mal evidence. The careful matching of explicit experience – the very definition of learning – but and implicit tasks that is characteristic of studies were apparently unable to gain conscious access to on implicit memory has not generally been imp- this knowledge. Thus, it appears that explicit orted into the study of implicit learning. A major learning can be dissociated from implicit learning. agenda item in the study of implicit learning is to

Following the model of implicit memory, imp- carry out more detailed analyses of subjects’ experi- licit learning may be defined as a relatively per- ences in implicit learning situations, to make sure manent change in knowledge, resulting from that they are really unconscious of what they evi- experience, in the absence of conscious awareness dently know and put into action. of what has been learned. Demonstrations that It is sometimes claimed that implicit learning is amnesic patients retain the ability to learn, even more powerful than conscious knowledge acquisi- thoughthey do not remember the learning experi- tion – that, for example, subjects can learn more ences themselves, have led some theorists to con- complicated things, and more quickly, implicitly strue implicit learning as a variant on implicit than they can explicitly. There may be cases in memory. However, there is an important distinc- which this is true – for example, the learning of tion between the two concepts: implicit memory is one’s native language(s). But for the most part, such a feature of episodic knowledge, in which subjects claims are rarely supported by adequately designed lack conscious memory for a specific event in their experiments. Most studies of implicit memory lives. By contrast, in implicit learning subjects lack are little more than demonstration experiments, conscious access to certain pieces of semantic or showing that something can be learned without procedural knowledge acquired through a learning any instruction or intention to do so, and with little experience. Cases where subjects are aware of conscious representation of what has been learned. knowledge acquired through a learning experi- But by and large, they lack the careful control ence, but cannot consciously recollect the learning conditions that would enable the investigators experience itself, are better classified as ‘source to pit conscious and unconscious learning against amnesia,’ a variant on implicit memory. Implicit each other. learning is also distinguished from merely ‘inciden- tal’ learning, in which new knowledge is acquired in the absence of instructions or intention to learn, Implicit Perception but the subject retains conscious access to that knowledge. Incidental learning is unintended, just Just as there are palpable effects on experience, as involuntary memory is unintended; but implicit thought, and action of past events that cannot be

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consciously remembered, there also appear to be observed in the ‘functional’ disorders of percep- similar effects of events in the current stimulus tion, such as cases of ‘hysterical’ blindness and environment, which cannot be consciously per- deafness (now relabeled ‘conversion disorder’), as ceived. By analogy with memory, explicit percep- well as in normal subjects given hypnotic sugges- tion may be identified with the subject’s conscious tions for blindness and deafness. Also in normals, perception of some object in the current environ- implicit perception has also been observed in sub- ment, or the environment of the very recent past, jects whose attention has been deflected from the as reflected in his or her ability to report the stimulus, so that it is processed outside conscious presence, location, form, identity, and/or activity awareness, as in parafoveal vision and dichotic of that object. By the same token, implicit percep- listening. Priming has also been observed in nor- tion entails any change in the person’s experience, mal failures of conscious perception such as ‘inat- thought, or action which is attributable to such an tentional blindness,’ as well as some forms of event, in the absence of (or independent of) con- ‘attentional’ blindness such as ‘repetition blind- scious perception of that event. Implicit percep- ness,’ and the ‘attentional blink’ (conscious per- tion is exemplified by what has been called ception also fails in the phenomenon of ‘change

‘subliminal’ perception, involving stimuli that are blindness,’ but to date there have been no demon- in some sense too weak to cross the threshold strations of priming in this phenomenon).

(limen) of conscious perception. As with implicit learning, implicit perception In the earliest demonstrations of subliminal effects are sometimes discussed under the rubric perception, the stimuli in question were of very of implicit memory. Indeed, the prime in most low intensity – ‘subliminal’ in the very strict sense implicit perception studies does occur in the of the term. Later, stimuli of higher, supraliminal past, but it is the past of only a few moments ago, levels of intensity were rendered ‘subliminal’ by with no intervening distraction – what James virtue of extremely brief presentations, or by the called the ‘specious present,’ and well within the addition of a ‘masking’ stimulus which for all span of primary memory. Implicit perception can practical purposes rendered the stimuli invisible. be distinguished from implicit memory as follows: Subliminal perception quickly entered everyday In implicit memory, the subject was perceptually vocabulary, as in the controversy over subliminal aware of the event at the time it occurred; but the advertising and the marketing of subliminal self- memory of that event has been lost to conscious help tapes. Almost from the beginning of this line recollection. In implicit perception, the subjects of research, a variety of methodological critiques were unaware of the event at the time it occurred; sought to undercut claims for subliminal percep- conscious recollection may be vitiated by the fail- tion. However, beginning with the now-classic ure of conscious perception, but it is the percep- studies of Marcel, followed by the work Merikle, tion itself, not memory, that is unconscious.

Greenwald, and their associates, an increasing body Preserved priming in general anesthesia might be of literature has demonstrated subliminal percep- construed as an instance of implicit memory, tion, broadly defined, in a manner that convincingly because the test of memory occurs some time addresses these criticisms. after the primes were presented; on the other The adjective ‘implicit’ is preferable to ‘sublim- hand, because the patients were not aware of the inal,’ because there are many cases of unconscious primes at the time they were presented, the same perception in which the stimulus is not subliminal phenomenon should also count as an instance of in the technical sense of the term. The most dra- implicit perception. matic example is that of ‘blindsight’ in patients With subliminal and other forms of implicit with lesions in striate cortex. Implicit perception perception now demonstrated to the methodolog- can also be observed in the syndromes of visual ical satisfaction of (almost) everyone, most of the neglect resulting from temporoparietal damage, remaining controversy concerns the extent of its and in discriminative physiological responses to influence. Dramatic claims for the power of sub- familiar and unfamiliar faces in cases of prosopag- liminal influence, popularized by Vance Packard’s nosia. Priming and related effects have also been expose ‘The Hidden Persuaders’ and revived in

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the American presidential election of 2000 by a distinction through learning. Similarly, Shames’ Republican television advertisement that appeared semantic priming effect resembles those observed to present the word ‘rats’ subliminally when dis- in implicit perception and memory – except that cussing the Democrats, appear to be grossly exag- the prime is neither a perceptual representation of gerated. In the past, debate focused on whether a current stimulus nor a representation available subliminal perception was limited to the analysis in memory of a stimulus presented in the past. of the physical characteristics of the subliminal The subjects in these experiments appear to exp- stimulus, as in repetition priming, or could extend erience a ‘feeling of knowing’ analogous to that to meaning analyses, leading to semantic priming. observed in metamemory tasks. Their choices The work of Marcel, Merikle, and Greenwald are clearly being guided by something that is nei- come down squarely in favor of semantic priming, ther a percept (because the solution is not cur- but even here subliminal perception appears to be rently being presented to them) nor a memory analytically limited. (because the solution has not been presented in the past). By analogy to implicit perception and memory, we may define ‘implicit thought’ as a

Implicit Thought mental representation – an idea or an image, for example – that influences ongoing experience,

Thinking and consciousness are so closely related thought, and action in the absence of conscious that the notion of unconscious thought seems to be awareness of that representation. a contradiction in terms – certainly James thought Implicit thought may underlie the intuition so. In line with Helmholtz’s concept of uncon- stage of insight problem solving: the subject has scious inferences, it is now generally accepted not yet consciously arrived at the solution, as a that many of the thought processes that intervene conscious insight, but knows that a solution is between perception and action are automatic, and possible, the solution itself is unconscious. In this it is in this sense that we may say that at least some analysis, the incubation stage may be thought of as thinking can occur outside of awareness. However, the process by which the transformation from there is some evidence that thoughts themselves, unconscious influence to conscious access takes and not just the process of generating them, can be place. Siegler and Stern may have observed this unconscious. In one example, Bowers and his transformation in children who were learning to associates found that subjects could distinguish solve a particular kind of problem, who showed by between soluble and insoluble puzzles, without their reaction times that they had achieved an knowing what the solution to the soluble puzzle insight into the solution of the problem, even was. Subsequent research has showed priming though their verbal reports indicated that they effects on lexical decision from the solutions to were not yet consciously aware of their insight. word problems, even when subjects were unaware Although intuition is commonly viewed as a of the solution itself. It has also been shown that source of error in human judgment, it may also subjects can display changes in skin-conductance be an adaptive component of the creative process – response when making objectively risky choices, gut feelings that motivate the problem-solver to even when they cannot subjectively distinguish keep working. In fact, Dijksterhuis and his collea- between those that are risky and those that are gues have argued that a reliance on intuition, or safe – much as prosopagnosic patients show differ- unconscious thinking, may be especially valuable in situations involving complex decision-making. ential physiological responses to objectively famil- iar faces that they cannot recognize. In some sense, the ability of Bowers’ subjects to discriminate between soluble and insoluble puz- The Unconscious beyond Cognition zles resembles the ability of Reber’s subjects to discriminate between grammatical and ungram- Intentional mental states go beyond cognitive matical letter strings – with the exception that states of perceiving, remembering, knowing, and they have had no opportunity to acquire the believing: they also include affective states, such as

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feelings of pleasure and pain, and motivational even though the subject has diverted attention states, such as the desire to approach or avoid. If away from the problem he is trying to solve. Atten- cognitive states can be unconscious, perhaps affec- tion, then, is neither necessary nor sufficient tive and conative states can be unconscious as for consciousness. well. Certainly, conscious feelings and desires can be generated automatically, in response to the appearance of effective stimuli in the environment. The Cognitive Unconscious and

In addition, conscious feelings and desires can Conscious Shyness emerge as expressions of implicit perception, memory, and thought – as in the subliminal mere The discovery of the unconscious is commonly exposure effect, by which subjects come to prefer (and erroneously) attributed to Sigmund Freud, stimuli to which they have been exposed, even if and there has been some tendency to claim that they were not consciously aware of the exposures, the literature on the cognitive unconscious pro- and cannot consciously remember them. Although vides support for the psychoanalytic conception most authorities currently hold the view that of unconscious mental life. This is not the case: unconscious feelings and desires are almost con- the unconscious percepts and memories revealed tradictions in terms, the general acceptance of the by contemporary cognitive psychology bear no cognitive unconscious suggests that we should resemblance to Freud’s primitive, infantile, sexual be prepared to accept the existence of an affective and aggressive urges. Moreover, the distinction unconscious, and of a conative unconscious, as between conscious and unconscious mental life well. Evidence in this regard is just beginning to appears to be a matter of cognitive architecture, trickle in, and at this point neither unconscious rather than of repression. Freud’s metapsychologi- emotion nor unconscious motivation has been cal proposition that some aspects of mental life are as well established as unconscious memory and unconscious is correct, but this is a proposition perception. that is not unique to psychoanalytic theory. The more specific propositions of psychoanalytic the- ory, to the extent that they are testable at all, have

Attention and Consciousness all failed to find empirical support. Revisited Still, just as Freud believed that unconscious

processes dominated mental life, so some psychol- One implication of research on implicit percep- ogists and other cognitive scientists have taken tion, memory, and thought is that consciousness evidence of unconscious perception, learning, is not as closely tied to attention as the distinc- and memory as reason for thinking that conscious tion between automatic and controlled processing mental activity plays little or no role in behavior. implies. It may seem obvious that attention is the For example, some personality and social psychol- means by which objects and events are brought ogists have shifted from ‘dual-process’ theories that into consciousness, and that consciousness entails some processes in social cognition and behavior are paying attention to such things. But in the case of consciously controlled, and others unconscious implicit perception, subjects may pay close atten- and automatic, to a view that social cognition and tion to the spatial location where a stimulus will behavior is dominated by unconscious, automatic appear, without being aware of the stimulus itself. processes, to the virtual exclusion of conscious,

In implicit memory, subjects may have attended controlled ones. Some writers have gone so far as to the study list at the time of learning, but fail to replace Freud’s view of the primacy of uncon- to consciously recollect it later. In implicit learn- scious sexual and aggressive motives with the more ing, subjects are attending to the manifest task modern concept of automaticity. which has been set for them, while being unaware Actually, there is no evidence (such as might be of knowledge they may have acquired in the provided by the process-dissociation procedure) course of task performance. And in implicit supporting the proposition that automaticity dom- thought, an insight may emerge into consciousness inates the conscious control of experience, thought,

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and action. Accordingly, the popularity of the view At the psychological level of analysis, uncon- that itdoes reflects a persisting ‘shyness’ about scious priming effects underscore the first-person consciousness noted by the philosopher Owen nature of the intentionality that underlies con- Flanagan. At the very least, evidence for automa- scious perception and memory. As James noted in ticity, and for unconscious perception, learning, the Principles, every conscious percept, memory, or and memory provide support for conscious ines- thought is part of a personal consciousness: ‘‘The sentialism, which holds that consciousness is not universal conscious fact is not ‘feelings exist’ or necessary for adaptive cognition and action to ‘thoughts exist’ but ‘I think’ and ‘I feel.’ ’’ Similarly, occur. Conscious inessentialism, in turn, can lead when subjects complete tests of explicit perception to epiphenomenalism, or the view that conscious- and memory, their answers are always couched in ness has no causal function at all. But it should be the first person: I see, I hear, I recall, or I recognize understood that the literature summarized here ‘X.’ By contrast, tests of implicit perception and only reveals the reality of unconscious cognition. memory are conducted in the third person: sub- It does not by any means negate consciousness. jects are asked to complete a word stem or frag- ment, or identify a word, and by and large their

answers lack this element of self-reference: that Neural and Psychological Correlates word is ‘X.’ Certainly, the subjects are conscious, of Consciousness and conscious of what they are doing, but in gen- eral implicit expressions of perception, memory,

The advent of brain-imaging research has added a learning, and thought lack the integration of the new dimension to research on unconscious mental percept, memory, or thought with the self that life, as researchers search for the neural correlates seems critical for conscious awareness. of conscious and unconscious processing. It seems clear, for example, that the striate cortex is required See also: Implicit Social Cognition; Unconscious Goals for conscious vision, but not for the unconscious and Motivation. vision revealed by blindsight. And the hippocam- pus and other portions of the medial temporal lobe appear to be necessary for conscious remembering, but not for priming and other aspects of uncon- Suggested Readings scious memory. Bargh JA and Ferguson MJ (2000) Beyond behaviorism: On More generally, comparisons of automatic ver- the automaticity of higher mental processes. sus conscious processing, and of implicit versus Psychological Bulletin 126(6 special issue): 925–945. explicit perception, learning, and memory, may Dehaene S, Changeux JP, Naccache L, Sackur J, and provide the comparison conditions necessary to Sergent C (2006) Conscious, preconscious, and subliminal processing: A testable taxonomy. Trends in identify the neural correlates of consciousness – Cognitive Sciences 10(5): 204–211. whichis to say, not the neural correlates of Dijksterhuis A and Nordgren LF (2006) A theory of conscious wakefulness (as opposed to general anes- unconscious thought. Perspectives on Psychological Science 1(2): 95–109. thesia or sleep), but rather the neural correlates of Ellenberger HF (1970) The Discovery of the Unconscious: conscious acts of perception, learning, memory, The History and Evolution of Dynamic Psychiatry. and thought. For example, automatic processing New York: Basic Books. Kihlstrom JF, Barnhardt TM, and Tataryn DJ (1992) Implicit appears to activate the sensory and motor repre- perception. In: Bornstein RF and Pittman TS (eds.) sentation areas of the brain, such as the primary Perception without Awareness: Cognitive, Clinical, and auditory cortex, while controlled processing is Social Perspectives, pp. 17–54. New York: The Guilford associated with areas of association cortex. Simi- Press. Kihlstrom JF, Mulvaney S, Tobias BA, and Tobis IP (2000) larly, presentation of a masked visual stimulus The emotional unconscious. In: Eich E, Kihlstrom JF, activates areas of the visual cortex (naturally), Bower GH, Forgas JP, and Niedenthal PM (eds.) Cognition while processing of the same stimulus unmasked, and Emotion, pp. 30–86. New York: Oxford University Press. activates a wider network of brain areas including Kihlstrom JF, Shames VA, and Dorfman J (1996) Intimations parietal and frontal regions. of memory and thought. In: Reder LM (ed.) Implicit

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Memory and Metacognition, pp. 1–23. Mahwah, NJ: Personality: Theory and Research, 3rd edn. New York: Lawrence Erlbaum Associates. Guilford. Koch C and Tsuchiya N (2007) Attention and consciousness: Stadler MA and Frensch PA (eds.) (1998) Handbook of Two distinct brain processes. Trends in Cognitive Implicit Learning. Thousand Oaks, CA: Sage. Sciences 11(1): 16–22. Underwood G (ed.) (1996) . Oxford: Oxford Moors A and DeHouwer J (2006) Automaticity: A theoretical University Press. and conceptual analysis. Psychological Bulletin 132(2): Weiskrantz L (1997) Consciousness Lost and Found: 297–326. A Neuropsychological Exploration. Oxford: Oxford Schacter DL (1987) Implicit memory: History and current University Press. status. Journal of : Learning, Westen D (1999) The scientific status of unconscious Memory, and Cognition 13: 501–518. processes: Is Freud really dead? Journal of the

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Biographical Sketch

John F. Kihlstrom received his PhD in personality and experimental psychopathology from the University of Pennsylvania in 1975, and is currently a professor in the Department of Psychology, University of California, Berkeley, where he also directs the undergraduate program in cognitive science. Kihlstrom previously held faculty positions at Harvard, Wisconsin, Arizona, and Yale. He is perhaps best known for his research on hypnosis, a field in which he has won many awards. His 1987 Science paper on ‘The cognitive unconscious’ is often credited with consolidating the emerging literature on unconscious mental life. He also expanded the concept of implicit memory to perception, thinking, and emotion.

Encyclopedia of Consciousness (2009), vol. 2, pp. 411-421

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Kihlstrom J F (2009), Unconscious Cognition. In: William P. Banks, (Editor), Encyclopedia of Consciousness. volume 2, pp. 411-421. Oxford: Elsevier.