The dual nature of hypnosis, in which alterations in consciousness occur in an interpersonal context, has meant that theoretical attempts to understand the phenomenon have been entangled in dichotomies. This has been the case since Mesmer, who thought his effects were due to a magnetic fluid, while the French royal commission attributed them to imagination. Charcot thought hypnotizability was a matter of neurology, while Liebeault and Bernheim emphasized suggestion. Sometimes these dichotomies are manifested within a single individual: Braid began with ideas about the paralysis of nerve centers and ended up emphasizing attention, imagination, expectation, and personality.
In the modern era these dichotomies are still visible, if somewhat obscured by theoretical nuance. Thus, the traditional (if perhaps somewhat tacit) view that hypnosis involves a "special" or "altered" state of consciousness is opposed by a variety of social -psychological or cognitive - behavioral views which assert that hypnotic behavior is a result of processes that are in every sense ordinary. However, there is considerable heterogeneity of viewpoint within each camp, which is sometimes ignored by the other side (a common feature of intergroup relations, according to social psychologists). Among those who are sometimes labeled as state theorists (including the present writer) are cognitive psychologists who think that hypnosis involves dissociative processes, psychoanalysts who invoke adaptive regression in the service of the ego, and neuroscientists who emphasize the inhibition of cortical structures. Among the critics of the state view are some who claim that hypnotic effects can be produced in the absence of a hypnotic induction, so long as subjects are appropriately motivated and instructed. There are others who emphasize the importance of prescriptive social roles played out by both hypnotist and subject, the self-fulfilling effects of expectancies,
Hypnosis and the Psychological Unconscious and the role of attributional processes and self-deception. While some social - psychological and cognitive -behavioral theorists have spent a great deal of time debunking exaggerated or erroneous claims about hypnosis, this has been no less true for some state theorists.
Although it is sometimes popular to portray this theoretical dispute as a kind of enduring debate, there is as much controversy within each camp as there is between camps, and in the final analysis most hypnosis research is designed more to illuminate the nature of specific hypnotic phenomena such as analgesia or amnesia than to provide evidence for any overarching theory of hypnosis. Nevertheless, scientists are trained to test hypotheses derived from theories, and, if possible, to test single hypotheses that will decide between competing theories, so that any empirical evidence obtained tends to be construed as evidence for one view or another.
In the early 1960s, J. P. Sutcliffe published a pair of seminal papers that contrasted a credulous view of hypnosis, which holds that the mental states instigated by suggestion are identical to those that would be produced by the actual stimulus state of affairs implied in the suggestions, with a skeptical view, which holds that the hypnotic subject is acting as if the world were as suggested. This is, of course, a version of the familiar dichotomy, but Sutcliffe also offered a third view: that hypnosis involves a quasi-delusional alteration in self-awareness—a delusion that is constructed out of the interaction between the hypnotist's suggestions and the subject's interpretation of those suggestions. Hypnosis is simultaneously a state of (sometimes) profound cognitive change, involving basic mechanisms of perception, memory, and thought, and a social interaction, in which hypnotist and subject come together for a specific purpose within a wider sociocul-tural context. A truly adequate, comprehensive theory of hypnosis will seek understanding in both cognitive and interpersonal terms. We do not yet have such a theory.
The psychological unconscious refers to the idea that mental states—cognitions, emotions, and motives— can influence ongoing experience, thought, and action outside of phenomenal awareness and voluntary control. Although the discovery of the unconscious is commonly attributed to Sigmund Freud, in fact, interest in unconscious mental states and processes goes back to the eighteenth century philosopher Leibnitz, who argued for the importance to perception of subliminal stimuli, and the nineteenth century psychophysicist Helmholtz, who argued that conscious perception results from unconscious inferences about environmental stimuli. Within contemporary cognitive psychology and cognitive science, interest in the psychological unconscious is almost entirely divorced from Freud and psychoanalysis.
In early cognitive psychology, the psychological unconscious was conceived as part wastebasket and part file cabinet. On the one hand, it was the repository for unattended inputs or for those contents of the sensory registers and short-term memory (STM) that had been rendered unavailable by virtue of decay or displacement. On the other hand, the unconscious was identified with the latent contents of long-term memory (LTM), which are brought into awareness when they are copied from LTM to STM. Later, acceptance of the distinction between automatic and effortful processes led to the idea that unconscious mental processes were executed automatically, without drawing on attentional resources. The upshot has been the identification of the unconscious with the unattended, and the rise of the notion that unconscious processing is limited to perceptual and other low-level, presemantic analyses.
More recently, unconscious processing has frequently been identified with the distinction between automatic and controlled mental processes. In some respects, the models for automatic processes are innate reflexes, taxes, instincts, and learned stimulus-response connections formed through classical and instrumental conditioning. Automatic processes are initiated independent of conscious intentions, are executed outside of awareness, and cannot be terminated until they have run to completion. Moreover, it appears that their execution consumes no attentional resources, so that they do not interfere with other ongoing perceptual-cognitive activities. Automatic processes are unconscious in the strict sense of the term: they are never directly available to conscious awareness and are known only by inference.
The automatic - controlled distinction refers to per
Hypnosis and the Psychological Unconscious ceptual- cognitive processes engaged in the course of perceiving, remembering, and thinking. The implication is that percepts, memories, and thoughts themselves are available to conscious awareness. Logically, however, availability is no guarantee of accessibility, raising the possibility that mental contents as well as mental processes might be unconscious. In fact, a wealth of experimental evidence, involving both braindamaged patients and normal subjects, supports a distinction between explicit and implicit memory. Amnesic patients or normal subjects who show preserved priming in the absence (or independent) of recall or recognition, constitute evidence for unconscious memory.
The explicit - implicit distinction can be extended to other psychological domains as well. In perception, for example, there is considerable evidence that stimuli which are subliminal, masked, or unattended can have effects on cognition and behavior even though the stimuli themselves are not consciously perceived. In cases of "blindsight," patients who have suffered damage to the striate cortex of the occipital lobe are able to respond appropriately to visual stimuli even though they are unable to see them. These experimental outcomes illustrate a distinction between explicit and implicit perception, analogous to the explicit-implicit distinction in memory. Explicit perception refers to the conscious perception of current events, as exemplified by the ability to locate and identify objects. By contrast, implicit perception refers to any effect of a current event on ongoing experience, thought, or action in the absence (or independent) of conscious perception, as exemplified by subliminal perception or blindsight.
The explicit-implicit distinction may also be relevant to discussions of thinking and problem solving. For example, intuitions about the solution to a problem, in the absence of conscious awareness of the solution itself, may be an example of implicit thought; incubation may reflect increases in activation associated with an implicit thought; and insight may occur once an implicit thought crosses the threshold required for conscious awareness.
It should be noted that the explicit - implicit distinction may be relevant to emotion and motivation as well as cognition. Many theorists distinguish among three components of an emotional response: subjective (or cognitive), referring to the person's conscious feeling state; behavioral, referring to overt motor activities associated with the emotion; and physiological, refer ring to associated covert somatic changes. Researchers have observed that these three components are not always positively intercorrelated, a situation known as desynchrony. A particular form of desynchrony, in which the subjective component of emotion is absent while the behavioral and physiological components persist, is tantamount to a dissociation between explicit and implicit emotion.
Implicit perception, memory, and thought serve as examples of preconscious cognition, in which the percepts and memories lie on the fringes of consciousness. Were the encodings deeper, or the retention interval shorter, or the retrieval cues richer, implicit memories might be consciously accessible. So, too, for implicit percepts: we would be conscious of them if only the stimuli contributing to implicit perception effects were of greater intensity or duration, or unmasked, or presented within the focus of attention. In general, the processing of preconscious percepts and memories is analytically limited. For example, the repetition priming effects obtained in the typical study of implicit memory are mediated by traces that represent the perceptual structure, but not the meaning, of the event in question. Semantic priming effects have been obtained in subliminal perception, but they are very weak and short-lived. Apparently, the conditions under which preconscious processing occurs do not permit very much to be done, cognitively, with these percepts and memories.
Hypnosis is relevant to the psychological unconscious because the phenomena of hypnosis appear to expand the boundaries of unconscious processing beyond the automatic and the preconscious. For example, the priming effects which are preserved in posthypnotic amnesia reflect semantic processing: the items in question were deeply processed at the time of encoding. Finally, the impairment in explicit memory is reversible: posthypnotic amnesia is the only memory disorder studied under laboratory conditions where implicit memories can be restored to explicit recollection. Taken together, then, these properties of priming in posthypnotic amnesia reflect the unconscious influence of semantic representations formed as a result of extensive attentional activity at the time of encoding. The priming itself may be an automatic influence, but it is not the sort that is produced by automatic processes mediated by a perceptual representation system or by presemantic or data-driven processing.
A second example is provided by posthypnotic suggestion, which appears to have a quasi-compulsive quality to it, especially when—as so often happens— the subject is unaware (by virtue of posthypnotic amnesia) that he or she is responding to the experimenter's cue. Thus it appears to be an automatic response to stimulation, but careful examination indicates that responding to the posthypnotic cue consumes atten-tional resources and interferes with other ongoing activities. Even though the posthypnotic suggestion is executed outside of the subject's awareness, and is experienced as involuntary, it is not automatic in the technical sense of being attention-free.
The identification of the psychological unconscious with automatic processing and with preconscious percepts and memories is popular, but if the phenomena of hypnosis are to be taken seriously, it is also misleading. Studies of hypnotic phenomena indicate that deep, semantic processing can occur without concurrent or retrospective awareness of what has been processed, and behavior executed outside of awareness can nonetheless consume attentional resources. The major contribution of hypnosis to our understanding of the psychological unconscious is the realization that there is more to consciousness than attention. At the very least, the phenomena of hypnosis seem to require another category, besides automatic processes and pre-conscious contents, in the taxonomy of unconscious mental life: subconscious contents. Subconscious percepts are in no sense subliminal or unattended; subconscious memories are in no sense weakly encoded. Yet neither are accessible to conscious awareness.
Hilgard and others have suggested that the phenomena of hypnosis and similar phenomena observed in other altered states indicate that consciousness can be divided, so that attentive, semantic processing can proceed outside phenomenal awareness. Hilgard's neo-dissociation theory of divided consciousness characterizes the mind as a set of modules that monitor and control mental functions in different domains. In the normal case, these modules are organized to be able to communicate with each other and with a central cognitive structure—what Hilgard calls the executive ego—which serves as the end point for all conscious inputs and the point of origin for all conscious outputs. This executive ego provides the cognitive basis for the phenomenal experiences of awareness and intentionality.
However, neodissociation theory also asserts that certain conditions, one of which is hypnosis, can alter the integration of the various cognitive structures. If the lines of communication between two subordinate structures are cut, they may perform input-output functions in the absence of any coordination between them. If the communication between a subordinate structure and the executive ego is disrupted, the domain-specific module will perform its function in the absence of the phenomenal experience of awareness and intentionality. In descriptive terms, both cases constitute states of dissociation.
Neodissociation theory holds that responses to suggestions are executed by the subordinate cognitive substructures, alone or in combination, independent of involvement of the executive ego. In the case of posthypnotic amnesia, for example, the events and experiences of hypnosis are processed by modules dedicated to learning and memory; when the suggestion for posthypnotic amnesia is given, the normal communicative link between these modules and the executive control structure is disrupted. Thus, when the executive control structure tries to gain access to these memories in order to respond to an explicit memory test, it cannot do so. However, implicit memory functions such as priming, which do not require conscious access mediated by the executive control structure, are unimpaired. Similarly, posthypnotic suggestions are executed by the relevant substructures without involvement of the executive. Because the executive has no awareness of this activity, the behavior in question is experienced as automatic, even though it may be quite complex and cognitively demanding. Although some critics have interpreted dissociation theory as implying that dissociated activities should not interfere with other ongoing functions, it should be apparent that such a system of dissociated control may well make considerable demands on cognitive resources, resulting in decrements in the performance of simultaneous tasks.
How this dissociation occurs is not well understood. However, the neodissociation theory of divided consciousness, proposed in the context of hypnosis,
Hypnosis and the Psychological Unconscious has stimulated a revival of interest in various forms of dissociation observed clinically, such as psycho-genic amnesia, fugue, and multiple personality (dissociative identity disorder). In addition to these clinical syndromes, which fall under the diagnostic rubric of "dissociative disorders,'' it has been noted that the various "conversion disorders,'' such as functional blindness, deafness, and paralysis, are essentially dissociative in nature. In each case, some aspect of perception or memory is split off from awareness. Research on the mechanisms of dissociation is at an early stage, but it is already clear that the phenomena of hypnosis, and the clinical syndromes which they resemble, expand the domain of the psychological unconscious and constitute major challenges to our understanding of the nature of conscious and unconscious mental life.
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