Final answer:
The statement is true; hallucinogens can indeed cause people to see things that are not present, leading to visual hallucinations and other perceptual anomalies.
Step-by-step explanation:
True: Hallucinogens are drugs that can make you see things that aren't really there. These substances lead to profound changes in sensory and perceptual experiences, such as visual hallucinations, and can alter a person's sense of reality. Users may experience things like seeing images, hearing sounds, or feeling sensations that do not exist in reality. An example of a classic hallucinogen is LSD, known to be one of the most potent mood-altering substances.
While the exact mechanisms behind their effects are not yet fully understood, it is believed that hallucinogens work by disrupting the communication between neurotransmitters in the brain and spinal cord, which regulate mood, sensory perception, sleep, and other functions. Therefore, the consumption of hallucinogens leads to a range of sensory and physical effects that can include hallucinations, an increased sense of energy, and changes in perception of time or synesthesia, where senses might be mixed up, like 'seeing' sounds.