Which group of drugs is the oldest known for their effects on perception?

Hallucinogens are recognized as the oldest group of drugs known for their profound effects on perception. These substances have been used for centuries, even millennia, in various cultures for spiritual and ritualistic purposes. Historical accounts indicate that different societies have utilized natural hallucinogens, such as psilocybin mushrooms, peyote (containing mescaline), and ayahuasca, as part of their cultural traditions to alter consciousness and enhance perception.

The effects of hallucinogens primarily involve significant changes in sensory perception, thought processes, and emotional experiences, leading to altered realities that distinguish them from other drug categories. This unique capacity to transform one's perception of reality places hallucinogens at the forefront of drug classes known for their perceptual effects, thereby confirming their historical significance and longevity in human use.