Abstract
The combination of ethnographic and cognitive neuroscience research provides considerable insight into the origin and symbolism of Native Californian rock art. Although made by different social groups for different purposes in various parts of the state, the ethnographic record demonstrates that the art depicts the mental imagery and somatic hallucinations of trance, taken to represent supernatural experiences. When this art is viewed from a cognitive neuroscience perspective, it suggests that the shamanistic state of consciousness was far from primarily "ecstatic," instead often involving the generation of unpleasant emotions; and that biochemical changes during trance necessitated the making of rock art if the memory of these supernatural experiences was to be preserved.