So far, we’ve considered drugs that may change the tone of someone’s conscious experience as well as make the person more sensitive to his sensory experiences. A final category of drugs is different: The hallucinogens are drugs that powerfully change perception and can also trigger sensory experiences in the absence of any inputs. These hallucinogenic effects are produced by many substances, including LSD (lysergic acid diethylamide, or “acid”), mescaline (from the peyote cactus), psilocybin (from certain mushrooms), and PCP (phencyclidine, often called “angel dust”).
All of these chemicals produce enormous changes in how the user perceives the world. They may trigger a sense of seeing fantastic and intricate patterns, an intense kaleidoscope of colors, or a series of meaningful images—some fantasy, some apparently based on the user’s emotional experiences. These experiences may trigger or be accompanied by intense emotions, ranging from euphoria in a “good trip” to deep panic or profound paranoia in a “bad trip,” with the consequence that one person might be exhilarated by the experience while another is horribly disturbed.
Hallucinogens seem not to produce dependence. However, due to the unpredictable nature of the experience, users always risk having a hallucination that’s deeply distressing. What’s more, in the hallucinatory state people often have dreamlike experiences that seem compelling and real; if the person takes these experiences at face value, she can put herself into enormous danger—for example, trying to jump out a window because she’s convinced she can fly. In response to these risks, users of hallucinogenic substances often choose to have a support network close at hand— friends who can serve as so-called trip sitters. These are people who aren’t using the drug and who stay with the hallucinating person in case the emotions of the trip turn dark or she decides to explore some hazardous activity.