The effects of hallucinogens on blind monkeys

Two blind monkeys were studied with an observational profile that was previously shown to distinguish the effects of hallucinogens from those of other classes of drugs. Lysergic acid diethylamide and dimethyltryptamine could be distinguished from saline, chlorpromazine, d-amphetamine sulfate, and bromo-lysergic acid diethylamide by the increased frequency of spasms, stereotypy, bump, and tracking. The hallucinogens also produced dramatic increases in exploration and related behaviors normally seen only in response to real visual or auditory stimuli. These behaviors are discussed in terms of their similarity to behaviors observed with sighted monkeys in light and dark environments.