As psychology shrugged off radical behaviorism, its renewed interest in mental life was focused on cognition, and it treated cognition as cold and hard, conscious and deliberate. As the cognitive revolution developed, however, two trends emerged. On the one hand, cognitive psychology made increasing room for the cognitive unconscious (Kihlstrom, 1987), as reflected in the rise of research on automaticity and on implicit memory. On the other hand, largely under the influence of personality, social, and clinical psychology, the study of cognition expanded to include the hot and the wet -- reflected in increased interest in emotional and motivational influences on memory and other cognitive processes. This second trend seems to have eventuated in an "affective revolution", in which emotional life is studied in its own right, and not merely as a byproduct of cognitive processing. But this affective revolution, epitomized by the emergence of an interdisciplinary "affective science" modeled on cognitive science, seems to be focused on conscious feeling states. I want to argue that it is time for the new science of emotion to entertain the possibility of an emotional unconscious (Kihlstrom, Mulvaney, Tobias, & Tobis, 1998).
Of course, the idea of an emotional unconscious is not new. As we all know, Sigmund Freud argued that our conscious experience, thought, and action is shaped by emotional and motivational states of which we are unaware. All the classic Freudian defense mechanisms were designed to render us unaware of our true emotional states. However, in order to talk about the emotional unconscious we need not embrace the whole conceptual panoply of classical, or even neoFreudian, psychoanalysis -- we dn't need the division of the mind into id, ego, and superego, the theory of infantile sexuality, the stages of psychosexual development, repression, or any of the rest of it. Modern research on cognition and the cognitive unconscious owes nothing whatsoever to Freud, and that is also the case with modern research on emotion and the emotional unconscious.
By way of background, let us review the scope of the cognitive unconscious (Kihlstrom, 1998). There is, first of all, the idea of automaticity (e.g., Hasher & Zacks, 1979) -- the notion that some mental and behavioral processes are executed reflexively and outside awareness in response to appropriate environmental stimuli. Some automatic processes are innate; others are automatized by virtue of extensive practice. The concept of automaticity allows unconscious processes to play a role in cognition, but it implies that the psychological unconscious is limited to mental processes, and that the contents on which these processes operate are conscious.
That this is not the case is shown clearly by research on implicit memory (Schacter, 1987). By contrast to explicit memory, which refers to the conscious recollection of some past episode of experience, implicit memory refers to any effect of a past event on any aspect of a person's ongoing experience, thought, and action. The classic example is "priming", in which the occurrence of an event facilitates (or, in the negative case, impairs) the processing of a subsequent event. A vast amount of evidence, including studies of brain-damaged patients as well as of intact subjects, shows clearly that explicit and implicit memory can be dissociated, so that priming can occur in the absence of conscious recollection of the priming event.
By analogy to implicit memory, we can define implicit perception as the influence of a current event, or an event in the very recent past, on experience, thought, or action, in the absence of conscious perception of that event (Kihlstrom, Barnhardt, & Tataryn, 1992). Although the concept of implicit perception is not universally embraced, fairly compelling evidence of a dissociation between explicit and implicit perception comes from studies of blindsight and neglect in brain-damaged patients, and studies of so-called "subliminal" and "preattentive" processing in intact subjects, all of which show that priming can occur in the absence of conscious perception of the priming event. The distinction between implicit perception and implicit memory is not always easy to make, because both phenomena are revealed by post-exposure priming effects -- that is, by performance on a nominal test of implicit memory. In my view, however, the term implicit memory should be reserved for cases where the stimulus event was consciously perceived at the time of encoding; where there is no conscious awareness at the time of encoding, then we can consider priming effects as evidence of implicit perception.
Continuing the analogy, we can define implicit learning as the acquisition of new knowledge and patterns of behavior through experience, in the absence of awareness of the knowledge or behavior so acquired (Reber, 1967). Research on implicit learning is exemplified by work on artificial grammar learning, the control of complex systems, and the learning of sequential structures. In each of these cases, the claim is that people's behavior is shaped by prior experience, even though they cannot report the nature of that influence. Admittedly, the research to date is not entirely convincing in this respect, for above-chance behavior could be mediated by partial conscious knowledge, but lots of people are working very hard on the problem, and that's what important for our purpose today.
Finally, we can define implicit thought as the influence of some cognitive representation, itself neither a percept nor an episodic memory, on experience, thought or action in the absence of conscious awareness of that representation (Dorfman, Kihlstrom, & Shames, 1996). For example, it turns out that subjects can choose which of two problems is soluble without knowing the answer to the soluble one; and that this solution can prime the processing of other events, even though the subject does not know what the solution is. Implicit thought may well underlie some of the most interesting facets of creative thought: intuition, incubation, and insight (Kihlstrom, Shames, & Dorfman, 1996), and I think we will begin to see more research on this topic in the very near future.
These four categories of phenomena -- implicit memory, perception, learning, and thought -- comprise the cognitive unconscious. With respect to the emotional unconscious, the first thing that should be noted is that conscious emotional responses can serve as expressions of implicit memory and perception, and perhaps implicit learning and thought as well. In both cases, the people in question are consciously aware of their feeling state, but are unconscious of the source of those emotions in their past or current experience.
On the memory side, brain-damaged, amnesic patients can acquire new emotional responses through experience, even though they cannot consciously remember the experiences themselves. For example, a study by Marcia Johnson and her colleagues exposed alcoholic Korsakoff syndrome patients, who suffer an anterograde amnesia as a result of bilateral damage to the diencephalon, to unfamiliar Korean melodies (Johnson, Kim, & Risse, 1985). Some melodies were played only once during the study phase, while others were played 5 or 10 times. Later, the patients were played these same melodies, along with other Korean melodies that were entirely new, and asked to indicate which they preferred. Both amnesic patients and control subjects preferred the old over the new melodies, reflecting what Robert Zajonc (1968) has called the "mere exposure effect". However, the patients, being amnesic, showed greatly impaired levels of recognition: they liked what they heard, but they didn't know why.
And with respect to perception, we now know that intact subjects can show mere exposure effects on preference judgments even though the exposures were so degraded as to be consciously imperceptible. A case in point is a study by Kunst-Wilson and Zajonc (1980), involving tachistoscopic presentations of drawings of irregular polygons. The subjects in this case were neurologically intact, but the exposures were so brief that they were not consciously perceived by the subjects, as confirmed by a later recognition test. Nevertheless, the subjects showed the mere exposure effect: the more subliminal presentations the stimuli received, the more the subjects liked them. The subjects liked what they saw, but they didn't know why.
This much is pretty clear from the available research, although I should say that more needs to be done in both arenas. In particular, the acquisition of emotional responses by amnesic patients has not been studied much since Johnson's original work. However, in view of the ongoing debate over recovered memories of trauma, I feel obliged to enter a strong cautionary note. The recovered memory literature frequently distinguishes between a conscious "recall memory" and an unconscious "feeling memory", the latter term referring to an emotional response to a current situation which is triggered by an unconscious memory of past trauma. The notion of a feeling memory is a throwback to the prepsychoanalytic notion of Freud that "hysterics suffer... from reminiscences", and finds some support in experimental demonstrations of emotion as an expression of implicit memory. But there is an important difference: the experimental literature provides independent corroboration of the past emotion-eliciting event -- information which may be rarely available in clinical practice. Nevertheless, clinicians who embrace the concept of recovered memory may inappropriately infer a history of prior trauma from the patient's current emotional state, in the absence of any independent corroborative evidence. This is, of course, a mistake -- the logical mistake of "affirming the consequent" -- a mistake which may lead patients to reconstruct distorted or false memories of their past. While there is no question that implicit memories of trauma can, in principle, affect a person's current experience, thought, and action, in the absence of independent, objective, corroboration there is no scientific basis for inferring the past from current emotional symptoms.
Let us now turn to the other side of the emotional unconscious -- the proposition that people can be unaware of emotional states which nonetheless influence their ongoing experience, thought, and action. Here it must be admitted at the outset that the relevant research is much more sparse, and much less convincing, than that which supports the notion that emotion can be an expression of implicit perception and memory. But still and all, the hints are very provocative: so let me share some of them with you.
The inspiration for this idea comes from Peter Lang's (1968) multiple-systems theory of emotion. According to Lang, every emotional response consists of three components: verbal-cognitive, corresponding to a subjective feeling state such as fear; overt motor, corresponding to a behavioral response such as escape or avoidance; and covert physiological, corresponding to a change in some autonomic index such as skin conductance or heart rate. We usually think of these three components or systems as covarying together: when people feel afraid, their heart rates go up and they avoid the fear stimulus. When their fear is reduced, heart rate and avoidance decrease as well. However, Lang has proposed that these three systems are partially independent, so that under some conditions they can move in quite different directions. Thus, Lang and Lazovik (1963), in their classic study of systematic desensitization of snake phobia, found that some subjects would show substantial changes in avoidance behavior, while still expressing fear of the snake. Rachman and Hodgson (1974) picked up on Lang's theme and applied the term desynchrony to cases where one component of emotional response was dissociated from the others.
Given that both Lang and Rachman and Hodgson were writing from a tradition of behavior therapy, which emphasizes objective measurement, it is perhaps natural that they were most interested in desynchronies between the behavioral and physiological components of emotion. However, I am interested in cases that represent the emotional analog of the explicit-implicit distinction in memory: where the subjective component of an emotion, the conscious feeling state, is absent, while the behavioral and/or physiological components persist outside of phenomenal awareness. If any of you know of well-documented examples, in the clinical or experimental literatures, I ask you to send them to me for my butterfly collection.
One illustration of the dissociation between explicit and implicit emotion comes from hypnosis: the phenomenon of hypnotic analgesia. Following appropriate suggestions, many highly hypnotizable subjects report feeling no pain when exposed to normally painful stimulation. Although hypnotic analgesia may be construed as a special case of sensory anesthesia, there is more to pain than mere sensation. In addition to sensory pain, which provides information about the location and severity of an irritation or injury, there is an explicitly emotional component of suffering which is not present in the other skin senses, such as touch and temperature. Sensory pain and suffering are dissociable in terms of subjects' pain ratings, and they appear to be mediated by different brain systems. The important thing, however, is that hypnotic analgesia can eliminate both sensory pain and emotional suffering. Hilgard has proposed that hypnotic analgesia is mediated by an amnesia-like dissociative barrier which blocks the subject's conscious perception and awareness of pain, but does not impair the registration of the pain stimulus outside of conscious awareness.
Accordingly, we would expect to see evidence of this registration in implicit indices of pain that do not require conscious awareness. And this is just what we find: hypnotic analgesia has little effect on physiological responses to pain stimulation. The diminution of sensory pain and suffering, along with the preservation of physiological responses to the pain stimulus, is exactly the sort of desynchrony we are seeking between explicit and implicit emotion.
Apparently, dissociations between emotional awareness and physiology are found quite commonly in the anxiety disorders. For example, cardiology clinics frequently encounter patients who complain of tachycardia, but who have no other signs of coronary arrest. It turns out that these patients are not having heart attacks at all; they're having panic attacks, even though they experience no subjective fear (aside from distress over the heart symptom itself). This syndrome even has a name: fearless panic attacks. The patient is showing all the physiological signs of fear, but doesn't experience fear itself. It would be interesting to know whether something similar occurs in response to actual fear stimuli in cases of phobia or obsessive-compulsive disorder.
The emotional deficits associated with schizophrenia also have a flavor of desynchrony. Thus, flat affect refers to a deficit in the behavioral expression or display of emotion, which may not extend to subjective experience or physiology. Interestingly, my new colleague Ann Kring, together with John Neale (1993), has shown that schizophrenics express less emotion than normals in response to emotional film clips, even though they do not differ in terms of self-reports of emotional experience. Unfortunately, this dissociation is not what the one we're looking for, because the conscious experience of emotion is not impaired. However, if we look at anhedonia, another feature of schizophrenia, and for that matter a dimension of normal personality as well, we may well find a deficit in the conscious experience of positive emotion which leaves the behavioral or physiological expressions of emotion unimpaired.
In fact, there may be a whole host of individual differences in emotional experience and expression which involve just this form of desynchrony. For example, Weinberger, Schwartz, and Davidson (1979) were interested in a group of subjects, labeled repressors, who reported low levels of trait anxiety, as shown on the Taylor Manifest Anxiety Scale (apologies to Charles Spielberger) but high levels of defensiveness on the Marlowe-Crowne Social Desirability Scale. Despite their general denial of distress, Weinberger et al. found, and Asendorf and Scherer (1983) subsequently confirmed, that these subjects showed increased response latencies and elevated levels of physiological response when asked to read sexual and aggressive verbal phrases. Perhaps people with a repressive coping style have a talent for desynchrony: they may not experience high levels of stress, even though their physiology is churning away anxiously. Unfortunately, so far as I can tell there has been no followup of this early evidence of implicit emotion.
Other individual difference variables may also be relevant to the emotional unconscious. For example, in alexithymia, which people have difficulty describing their emotional states, or in discriminating one emotional state from another. The restricted emotional life of alexithymics seems at least superficially similar to repressive coping style, and it may well be that they have "no words for moods" because they are not aware of their emotional feelings in the first place. Interestingly, alexithymia is a prominent feature among neurological patients who have undergone hemispheric commissurotomy, suggesting that the division in awareness includes an inability to communicate, via language centers of the left hemisphere, emotion arising from centers in the right hemisphere. The question is whether we can find evidence for implicit emotion in these patients, and in neurologically intact alexithymics as well, in terms of behavioral or physiological indices (Lane, Ahern, Schwartz, & Kaszniak, 1997).
On the developmental side, Richard Lane and his colleagues has proposed that there are five levels of emotional awareness, determined by the manner in which the individual's emotional states are organized (Lane & Schwartz, 1987). At the lowest level, the person is aware only of bodily sensations; at the next higher level, the person is also aware of action tendencies; but at neither level is the person aware of emotional feelings as such. This awareness begins to emerge only at the emotional counterpart of Piaget's "preoperational" level, and progresses to awareness of emotional blends and opposites, and finally to awareness of subtle nuances of emotion. According to Lane, emotional development does not necessarily parallel cognitive development, such that some adults, firmly ensconced in formal operations with respect to their cognitive abilities, may have only primitive, sensory-motor emotional reactions -- in other words, no emotional awareness at all. People operating a low levels of emotional awareness, then, might be expected to show a dissociation between explicit emotion, consciously experienced, and implicit emotion, expressed in behavior or physiology.
Turning from personality to social psychology, Greenwald and Banaji (1995) have recently applied the explicit-implicit distinction to the concept of attitude. This is interesting because, as Thurstone noted long ago, emotion is central to social attitudes: they are affective dispositions to favor or oppose certain individuals, groups, or policies, and they are measured on dimensions which have affective connotations: pro and anti, like and dislike, positive and negative, and so on. Classical social psychology assumes that people are aware of their attitudes, which is why attitudes are typically assessed by self-report scales. However, Greenwald and Banaji have suggested that people may possess positive and negative implicit attitudes about themselves and other people, which can affect ongoing social behavior outside of conscious awareness.
A particularly provocative demonstration that explicit and implicit attitudes can be dissociated is provided by Greenwald and Schuh's (1995) analysis of reference citation practices by social scientists. Social scientists in general, and prejudice researchers in particular, are generally supposed to be a pretty liberal bunch, and you probably could not get them to admit to ethnic prejudice if you held a gun to their heads. However, when Greenwald and Schuh classified authors' names into categories of Jewish, non-Jewish (presumably Gentile) and other, they found that authors were 40% more likely to cite colleagues from their own ethnic category. It seems that ethnic prejudice can influence citation behavior, even if it doesn't creep into conscious awareness.
An experimental demonstration of implicit attitudes is provided by a series of studies of the "false fame" effect by Banaji and her colleagues. For example, Banaji and Greenwald (1995) asked their subjects to study a list of names of famous and nonfamous men and women. Later, the subjects were presented with a longer list of famous and nonfamous names, including those studied previously, and asked to identify which were famous. Larry Jacoby and his colleagues have found that subjects tend to falsely identify previously studied nonfamous names as famous -- a kind of priming effect roughly analogous to Zajonc's mere exposure effect. But in Banaji's study, the false fame effect was bigger for male than for female names. Apparently, the average subject was more likely to associate achievement with males than with females revealing that they hold negative stereotypes about women.
The notion of implicit attitudes is provocative, but I have to enter another caution: it is one thing to demonstrate the implicit effect of attitudes on tasks that do not require conscious awareness of those attitudes, but it is something else to demonstrate that explicit and implicit attitudes are actually dissociable. We might like to think that the average social scientist is unprejudiced, and the average college student doesn't embrace gender stereotypes; but that might not be true, and if we actually asked them, they might well own up to their bias and bigotry. Recently, Wittenbrink, Judd, and Park (1997) performed a formal comparison of explicit and implicit racial attitudes. Their white subjects showed priming in a lexical decision task when positive trait words were preceded by the prime white, and negative traits were preceded by the prime black. This is evidence of implicit racial prejudice, but the magnitude of the race-specific priming effect was correlated with scores on a questionnaire measure of racial prejudice. So, there wasn't really any dissociation. Implicit measures may be very useful in studies of attitudes and prejudice, but researchers need to actually test for explicit-implicit dissociations before we accept implicit attitudes as evidence of an emotional unconscious whose contents are different from those which are accessible to phenomenal awareness.
Let me say a little more about the logic of inferring unconscious emotions. We recognize priming effects as evidence of implicit memory because we can trace them to specific objectively observable events, and we can objectively trace the relationship between the prime and the target. Put another way, we can identify an implicit expression of memory because we know what happened to the subject in the past. But by the same logic, in order to identify an implicit expression of emotion, we have to know what emotional state the subject should be experiencing -- which emotional state is being represented, and expressed, outside of conscious awareness.
In principle, this can be accomplished by considering the convergence of four operations on a hypothetical emotional construct. First, we need to know the adequate stimulus for emotion -- that is, we need to have a set of stimuli which, under ordinary circumstances, reliably elicit particular emotions in normal subjects. Next, we need to have reliable, valid measures of the subjective, behavioral, and physiological responses to the emotion stimulus. With these in hand, we can investigate the failures of convergence which underlie the concept of desynchrony. For example, if in the presence of a known fear stimulus, a person shows the behavioral and physiological components of fear, such as appropriate facial expressions and elevated heart rate, without the subjective experience of fear, we can say that we have demonstrated a dissociation between explicit and implicit emotion. Minor detail, that "if", because it depends on our being secure in the knowledge that particular environmental stimuli typically evoke particular emotional states, and that these emotional states are typically accompanied by particular patterns of behavioral response and physiological activity. Frankly, I don't think we're quite there yet.
Still and all, at least in principle, the emotional unconscious has two different aspects. On the one hand, we may be unaware of the percepts, memories, and thoughts which give rise to our emotional feelings. In this case, emotion serves as an implicit expression of perception, memory, and thought. On the other hand, we may be aware of what we are perceiving, remembering, or thinking, but unaware of the emotions instigated by these cognitions. In this case, behavioral and physiological changes serve as implicit expressions of emotion.
Interestingly, both aspects of the emotional unconscious are anticipated in the neuropsychological model of fear recently offered by Joseph LeDoux (1995). LeDoux argues that the amygdala, a structure in what is commonly called the limbic system, mediates fear. Specifically, he proposes that fear stimuli are processed by the amygdala, which in turn generates appropriate behavioral, autonomic, and endocrine responses. Cortical arousal, feedback of somatic and visceral information, and information about the fear stimulus are then integrated in working memory to generate the subjective experience of being afraid. Thus, if for some reason the eliciting stimulus is not represented in working memory, the person will experience fear without being aware of the fear stimulus -- in this case, emotion will serve as an implicit expression of perception or memory, as described earlier. Alternatively, a disconnection between the amygdala and the cerebral cortex can produce a dissociation between explicit and implicit emotion: the person will behave in a fearful manner without feeling fear or anxiety. The fact that a popular and powerful neuropsychological model of emotion can produce both aspects of the emotional unconscious is, in my view, warrant to pursue the matter further. Still, LeDoux's model is based almost entirely on animal research, and it would be nice to have positive evidence of implicit emotion in humans, who can talk to us about their conscious experiences.
So while the experimental and clinical evidence for a dissociation between explicit and implicit emotion is not yet convincing, and the methodological requirements for such demonstrations have not yet been fully met, the hypothesis of unconscious emotional states can no longer be rejected out of hand. If we are willing to speak of implicit percepts, memories, and thoughts that are dissociated from their explicit counterparts, then we must be willing to speak of implicit emotions in the same terms.
Paper presented at the "EMPathy" symposium on emotion, motivation, and personality, sponsored by the American Psychological Foundation, at the annual meeting of the American Psychological Association, San Francisco, August 1998. A fuller treatment of this topic is provided by Kihlstrom, Mulvaney, Tobias, and Tobis (2000). The point of view represented in this paper is based on research supported by Grants #MH-35856 and MH-44739 from the National Institute of Mental Health.
Asendorf, J.B., & Scherer, K.R. (1983). The discrepant repressor: Differentiation between low anxiety, high anxiety, and repression of anxiety by autonomic-fl-verbal patterns of behavior. Journal of Personality & Social Psychology, 45, 1334-1346.
Banaji, M.R., & Greenwald, A.G. (1995). Implicit gender stereotyping in judgments of fame. Journal of Personality & Social Psychology, 68, 181-198.
Dorfman, J., Shames, V.A., & Kihlstrom, J.F. (1996). Intuition, incubation, and insight: Implicit cognition in problem-solving. In G. Underwood (Ed.), Implicit cognition (pp. 257-296). Oxford: Oxford University Press.
Garner, W.R., Hake, H.W., & Eriksen, C.W. (1956). Operationism and the concept of perception. Psychological Review, 63, 149-159.
Greenwald, A.G., & Banaji, M.R. (1995). Implicit social cognition: Attitudes, self-esteem, and stereotypes. Psychological Review, 102, 4-27.
Greenwald, A.G., & Schuh, E.S. (1994). An ethnic bias in scientific citations. European Journal of Social Psychology, 24, 623-639.
Hasher, L., & Zacks, R.T. (1979). Automatic and effortful processes in memory. Journal of Experimental Psychology: General, 108, 356-388.
Hilgard, E.R. (1977). Divided consciousness: Multiple controls in human thought and action. New York: Wiley-Interscience.
Johnson, M.K., Kim, J.K., & Risse, G. (1985). Do alcoholic Korsakoff's syndrome patients acquire affective reactions? Journal of Experimental Psychology: Learning, Memory, & Cognition, 11, 27-36.
Kihlstrom, J.F. (1987). The cognitive unconscious. Science, 237, 1445-1452.
Kihlstrom, J.F. (1998, in press). Conscious and unconscious cognition. In R.J. Sternberg (Ed.), The concept of cognition (pp. xxx-xxx). Cambridge, Ma.: MIT Press. (a)
Kihlstrom, J.F., Barnhardt, T.M., & Tataryn, D.J. (1992). Implicit perception. In R.F. Bornstein & T.S. Pittman (Eds.), Perception without awareness: Cognitive, clinical, and social perspectives (pp. 17-54). New York: Guilford. (a)
Kihlstrom, J.F., Mulvaney, S., Tobias, B.A., & Tobis, I.P. (1998). The emotional unconscious. In E. Eich, J.F. Kihlstrom, G.H. Bower, J.P. Forgas, & P.M. Niedenthal, Counterpoints: Cognition and emotion (pp. xxx-xxx). New York: Oxford University Press.
Kihlstrom, J.F., Shames, V.A., & Dorfman, J. (1996). Intimations of memory and thought. In L. Reder (Ed.), Implicit Memory and Metacognition (pp. 1-23). Mahwah, N.J.: Erlbaum.
Kring, A.M., Kerr, S., Smith, D.A., & Neale, J.M. (1993). Flat affect in schizophrenia does not reflect diminished subjective experience of emotion. Journal of Abnormal Psychology, 102, 507-517.
Kunst-Wilson, W.R., & Zajonc, R.B. (1980). Affective discrimination of stmuli that cannot be recognized. Science, 207, 557-558.
Lane, R.D., Ahern, G.L., Schwartz, G.E., & Kaszniak, A.W. (1997). Is alexithymia the emotional equivalent of blindsight? Biological Psychiatry, 42, 834-844.
Lane, R.D., & Schwartz, G.E. (1987). Levels of emotional awareness: A cognitive-developmental theory and its application to psychopathology. American Journal of Psychiatry, 144, 133-143.
Lang, P.J. (1968). Fear reduction and fear behavior: Problems in treating a construct. In J.M. Schlein (Ed.), Research in psychotherapy (vol. 3, pp. 90-103). Washington, D.C.: American Psychological Association.
Lang, P.J., & Lazovik, A.D. (1963). Experimental desensitization of a phobia. Journal of Abnormal & Social Psychology, 66, 519-525.
LeDoux, J. (1996). The emotional brain: The mysterious underpinnings of emotional life. New York: Simon & Schuster.
Rachman, S., & Hodgson, R. (1974). I. Synchrony and desynchrony in measures of fear. Behaviour Research & Therapy, 12, 311-318.
Reber, A.R. (1993). Implicit learning and tacit knowledge: An essay on the cognitive unconscious. New York: Oxford University Press.
Schacter, D.L. (1987). Implicit memory: History and current status. Journal of Experimental Psychology: Learning, Memory, & Cognition, 13, 501-518.
Weinberger, D.A., Schwartz, G.E., & Davidson, R.J. (1979). Low-anxious, high-anxious, and repressive coping styles: Psychometric patterns and behavioral and physiological responses to stress. Journal of Abnormal Psychology, 88, 369-380.
Wittenbrink, B., Judd, C.M., & Park, B. (1997). Evidence for racial prejudice at the implicit level and its relationship with questionnaire measures. Journal of Personality & Social Psychology, 72, 262-274.
Zajonc, R.B. (1968). The attutidinal effects of mere exposure. Journal of Personality & Social Psychology, Monograph Supplement 9(2, Pt. 2).
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