Perception and Hallucination

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Image retrieved from on February 23rd, 2014.
Image retrieved from on February 23rd, 2013.

All is riddle, and the key to a riddle is another riddle. There are as many pillows of illusions as flakes in a snow-storm. We wake from one dream into another dream.

--Ralph Waldo Emerson

If we leave aside speculations about neurotransmitters or changes in particular areas of the brain and search for a more general conception of psychedelic drug effects, we come to the central organizing idea mentioned in chapter 4: alteration or impairment of the filtering mechanisms that regulate the access of perceptual and emotional stimuli to consciousness. We saw how this impairment of selective attention could account for heightened perception, changes in time sense, symbolic perception, loss of the boundaries of the self, primitive intense emotions, and accretions of excess meaning in everything seen or done. In animal experiments using a behaviorist model, LSD not only heightens the significance of a given level of stimulus (its effect on the animal's reward-seeking or avoidance of punishment) but also increases generalization: the transfer of conditioned responses to stimuli that resemble but are not identical with the one to which the response was originally conditioned. This is the process that gives meaning (defined as behavioral effect) to a previously neutral stimulus (Bradley and Key 1963; Claridge 1970).
If the main function affected is the ordering and evaluation of sensory hallucinations, in the broadest sense. The word “hallucinogenic” would in fact be accurate if “hallucination” still had its etymological root sense of mental voyaging or wandering, instead of suggesting an unequivocal distinction between what is real and what is not. Nothing infallibly distinguishes hallucinations and delusions from perceptions and thoughts. Perceptual characteristics like voluntariness, vividness, coherence, and intersubjective verifiability appear in different degrees on a continuum; the line between symbolic vision and illusion or between suspicion and paranoia is not always easy to draw. There is no objective, given world to be copied by our perception serves.
The signals that reach us from the external and internal environment are used to make a construction of reality. In the process we discover symbolic meanings and metaphorical connections and undergo changes in time perception, body feeling, and the sense of self. Usually variations and novelties in the way we put together our world are confined to a fairly narrow range of consciousness defined by the need to forsee danger, make plans, control our actions, and generally adapt to a complex environment. But if the need for control is absent or cannot be satisfied, the mind takes strange directions. In controlling output (behavior) as it ordinarily does. This situation arises when there are not enough novel external stimuli to keep the mind occupied: it also arises when the mind becomes so hypersensitive to stimuli, internal and external, that normal filtering and feedback mechanisms fail. The first situation is exemplified by REM sleep (dreaming sleep), during which the sense are delivering little new information and the skeletal muscles are immobilized, so that the body is not prepared for action, but the cortical centers of consciousness are at a high level of activity. There are also waking states in which the mind is deprived of novel stimuli—sensory deprivation in an isolation tank. Certain religious exercises in meditative concentration, possibly some drugs like ketamine. Whether by countering the inhibitory effect of the raphe cells or by some other means, LSD seems to give the mind too much to cope with rather than to little (see West 1975).
The states of mind induced in these various ways are far from identical, but they all have something in common. Sensory deprivation or overload prevents the orderly processing of new information, and the idle over worked brain begins to produce novel combinations of ideas and perceptions. Activity is heightened in the regions where memory traces enrich and transform one another and are subjected to interpretation and evaluation. Repressed feelings and memories are made available to consciousness. Either in symbolic fantasy form or as relived experience. These experiences sometimes seem more direct using its familiar categories to divide, distinguish, and select.
The fact that psychedelic experiences are produced by an unusual state of the nervous system is no reason to regard them as merely a pathological distortion of consciousness with nothing to teach us about the real world. That would be a genetic fallacy. It helps to recall, if only as a corrective, the Hindu and Buddhist judgment that everyday consciousness is maya, illusion. The combinations of the mind in altered states of consciousness are not random and senseless. Furthermore, the experiences produced with such intensity by psychedelic drugs also play a part in everyday life, where of course we properly take them only in small doses and in dilute form. There are many fruitful mixtures of what is usually called fantasy and what is usually called reality. Among the overinterpretations, misinterpretations, and delusions of altered mental states we also find the kind of creative interpretation that uncovers new realities; and we cannot always be sure which is which. To absorb in pure and concentrated form what we usually take in mixed and dilute form is not to turn away from reality but to investigate an important part of it. Placing these phenomena in an intellectual context that also includes the worlds of common sense and contemporary sciences is a difficult task that must be approached without to many preconceptions. In doing this it helps to consider more closely the relationship of psychedelic drug experience to other wanderings of the mind in the realms of madness, dream, artistic and scientific creation, and religious exaltation.

pp. 242-244 Psychedelic Drugs Reconsidered by Lester Grinspoon and James B. Bakalar (1997)

Ralph Waldo Emerson