A hallucinogen is an agent with a psychoactive effect. A hallucinogen binds to receptors in the central nervous system to exert its impacts on an individual. There are a number of hallucinations that can develop following the administration of a hallucinogen. Some of the most common changes include changes in sight, sound, thought, consciousness, and emotion. Individuals who take a hallucinogenic compound often describe sounds blurring together, seeing vivid colors, and images changing and distorting before their eyes. Typically, these changes are not experienced with drugs that fall into other categories. Some of the most common categories of hallucinogenic agents include psychedelics, dissociative, and deliriants. There may be some overlap with other drugs, as THC is a cannabinoid that can have some degree of psychoactive effect as well. One of the most common examples of a hallucinogenic drug is LSD, which is also called acid. Hallucinogens can also play a role in certain religious ceremonies and experiences, with some people claiming that these compounds help them purge negative energy and spirits from their bodies.