Which of the following substances is not classified as a hallucinogen?

The correct identification of a substance that is not classified as a hallucinogen is based on its pharmacological effects and how it interacts with the brain. Ethanol (ETOH), which is commonly found in alcoholic beverages, functions primarily as a depressant. It affects the central nervous system by slowing down brain activity and can induce relaxation and lowered inhibition but does not primarily cause hallucinations or distort perceptions of reality, which are hallmarks of hallucinogens.

Hallucinogens like DOM (a psychedelic compound), MDMA (which can have hallucinogenic properties at certain doses), and psilocybin (found in magic mushrooms) primarily alter perception, mood, and cognition, leading users to experience visual or auditory hallucinations. These distinctions are crucial in drug recognition training, as understanding the effects of each substance aids in accurately identifying their potential impact on users and assisting in law enforcement or medical scenarios. Thus, ethanol stands apart from these other compounds in its classification as it does not elicit the hallucinogenic effects associated with the other substances listed.