Perceptual change

C. Perceptual changes occurring in a stare of ftill wakefulness and alermess (e.g., subjective intensification of perceptions, depersonalization, derealization, illusions, hallucinations, synesthesias) that developed during, or shortly after, hallucinogen use. 

This is the sensory level of the psychedelic experience. Perceptual changes have transformed the organ music into a human voice. Sense impressions other than aural take form as Watts speaks of "a vast human throat, wet with saliva."... 

The paper by Aaronson deals with hypnosis. It recounts a series of experiments in which posthypnotic suggestions of perceptual change are given to normal subjects, and the resultant alterations in their behavior are observed. Some... 

All hypnotic subjects reported perceptual changes involving loss in all other sensory dimensions. One subject was appalled by the silence he felt around him. Another commented that he could move through a tree, and neither he nor the tree... 

Fogel, S., and Hoffer, A. "Perceptual Changes Induced by Hypnotic Suggestion for the Post-hypnotic State 1. General Account of the Effect on Personality," Journal of Clinical and Experimental Psychopathology 23, 24-35,1962a. 

Rebound may be contrasted with a withdrawal reaction in which stopping the hypnotic is followed by the emergence of new symptoms, not previously experienced by the patient. Muscle tension and pain, loss of appetite and weight, and perceptual changes such as hyperacusis are cardinal features of withdrawal reactions from benzodiazepine-type depressants. 

Effects First effects after 30 minutes (15 minutes with vitamin C), warm, pleasant spinal shivers, followed by psychic stimulation, heightening of emotional and sexual feelings, mild perceptual changes without hallucinations, sometimes spontaneous erections. Sexual activity is especially pleasurable. Feelings of bodies melting into one another. Total experience last 2-4 hours. Aftereffects pleasant, relaxed feeling with no hangover. See YOHIMBINE. 

Snuffed first effects occur within 5 minutes. Initial effect may include subtle psychic and perceptual changes, stimulation similar to concaine, and warm spinal shivers. Total experience lasts 2-4 hours gradually tapering. 

Other pleasurable effects are warm spinal shivers which are especially enjoyable during coitus and orgasm (bodies feel like they are melting into one another), psychic stimulations, mild perceptual changes without hallucinations, and heightening of emotional and sexual feeling. ... 

The interaction of the dopamine antagonist haloperidol 5 mg orally with subanesthetic doses of ketamine has been studied in a placebo-controlled study in 20 healthy volunteers over 4 days (53). Haloperidol pretreatment reduced impairment of executive cognitive functions produced by ketamine and reduced the anxiogenic effects of ketamine. However, it failed to block the ability of ketamine to produce psychosis, perceptual changes, negative symptoms, or euphoria, and it increased the sedative and prolactin responses to ketamine. These results imply that ketamine may impair executive cognitive functions via dopamine receptor activation in the frontal cortex, but that the psychoactive effects of ketamine are not mediated via dopamine receptors, but rather via NMDA receptor antagonism. 

Physical dependence on benzodiazepines is recognized as a major problem, and occurs after relatively short periods of treatment (50,51), particularly in patients with a history of benzodiazepine or alcohol problems. Abrupt withdrawal can cause severe anxiety, perceptual changes, convulsions, or delirium. It can masquerade as a return of the original symptoms in a more severe form (rebound), or present with additional features (SEDA-17,42 11). Up to 90% of regular benzodiazepine users have adverse symptoms on withdrawal. The differences between rebound, withdrawal syndrome, and recurrence have been reviewed in detail (3). 

There are also on-going nontherapeutic psilocybin research projects taking place in other countries. One project studies the effects of psilocybin on binocular depth inversion, binocular rivalry, neuropsychology and synaesthesias. It is headed by Dr. Torsten Passie, M.D., at the Medical School of Hannover, Germany. The study involves the use of medium doses of psilocybin to examine the effects on neuropsychological measures (attention, reaction time, etc.), perceptual changes, and subjective effects. 

In 14 healthy subjects, ketanserin attenuated the perceptual changes, emotional excitation, and acute adverse responses induced by ecstasy, but had little effect on positive mood, well-being, extroversion, and short-term sequelae (3). Body temperature was lower with ecstasy plus ketanserin than with ecstasy alone. 

Stronger evidence supports the notion that cannabis use alters perception, such as taste, smell, hearing and vision. In users there are clear problems of colour discrimination (Adams et al. 1976) and identification of figures hidden in pictures (Pearl et al. 1973). Perceptual changes also pertain to time sense, which is generally altered in cannabis users. As they estimate time to pass more slowly than control subjects (Tart 1971 Chait and Pierri 1992), this could explain... 

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