Vision-inducing plants ("hallucinogens") are important in many societies, evoking powerful emotional, psychological, cognitive, religious, spiritual, therapeutic and political reactions. These substances' psychophysiological properties shape cross- cultural similarities in patterns of use and experiences, while political factors shape their cultural desirability. Neurological studies illustrate that common effects are based in intervention in serotonergic neurotransmission. Effects upon neural, sensory, emotional, and cognitive processes stimulate integrative information processing, justifying a new term - "psychointegrators." Psychointegrators disin hibit sensory and emotional processes. They stimulate systemic integration of brain information-processing functions, enhancing integration of limbic system self and emotional dynamics with neocortical processes. Their therapeutic applications are reviewed from perspectives of cross-cultural and clinical studies.