A psychedelic experience is a psychological event in which the perception is temporarily but dramatically altered. This alteration of the perception has many possible manifestations, such as visual hallucinations and the perceived distortion of time. The psychedelic experience is most commonly associated with psychoactive drugs like lysergic acid diethylamide (LSD), but can also arise from certain drug-free activities, particularly sensory deprivation sessions. In rare cases, those in the midst of a psychedelic experience may be overcome by feelings of dread and terror. This phenomenon is known as a “bad trip.”
The substances and activities that induce psychedelic experiences are believed to temporarily suspend the brain’s tendency to “filter” the awareness. Under normal circumstances, this filter limits the perceptions which reach the consciousness. Those who have undergone a psychedelic experience report that the suspension of this filter results in a dramatically widened sense of awareness.
This sense of altered awareness can take a number of forms. Many report visual hallucinations, including the perception of incredibly vivid colors and repeating geometric patterns, as well as the sense that stationary objects are moving or changing shape. Some people experience the sensory confusion known as synesthesia, feeling, for instance, that they can “see” music. Also common is the distortion of time — some report that a single experience can seem to last for many years — and the breakdown of the sense of self, resulting in a feeling of communion with the universe.
Numerous drugs, both natural and manmade, can induce a psychedelic experience. Naturally occurring psychedelic substances include mescaline, psilocybe mushrooms, and ayahuasca tea. Even cannabis can sometimes produce mild psychedelic effects when smoked in large quantities. LSD is perhaps the most well-known manmade psychedelic, though other synthetic drugs such as methylenedioxymethamphetamine (Ecstasy) can also bring on psychedelic events.
Certain drug-free activities have also been reported to bring on psychedelic experiences. Most prevalent among these is sensory deprivation, in which an individual is placed in a lightless, soundproof environment such as a tank or small chamber. With the senses temporarily stripped away, some sensory deprivation participants report experiencing psychedelic events such as visual and auditory hallucinations.
In rare instances, a psychedelic experience is characterized by intense feelings of dread, terror, and panic. This occurrence, sometimes known as a bad trip, has no clear medical explanation, lending an element of unpredictability to the ingestion of psychedelic drugs. Those experiencing a bad trip may be overcome by the fear that they will never regain normal consciousness. They may also face terrifying visual hallucinations, such as the perception that their skin is covered with insects. Those in the presence of someone suffering a bad trip should attempt to prevent the sufferer from harming himself or those around him.