Which of the following is an effect of hallucinogenic drugs?

Hallucinogenic drugs are known for their profound effects on a person's sensory perceptions, leading to alterations in how they experience reality. This includes visual and auditory hallucinations, distortions in perception of time and space, and an overall shift in emotional and cognitive processing. Such changes can make a person see, hear, or feel things that are not actually present in reality, which is the hallmark of hallucinogenic experiences.

While improved motor skills, reduced need for sleep, and increased appetite might be effects associated with other categories of drugs, they are not characteristic of hallucinogens. Instead, hallucinogens primarily disrupt normal sensory pathways, resulting in the altered perceptions that are key to their classification. This makes altered sensory perceptions not only the correct answer but also the fundamental effect used to recognize hallucinogenic substances in a practical context.