Visual hallucinations induced by Ganzflicker and Ganzfeld differ in frequency, complexity, and content
Scientific Reports January 29, 2024 Oris Shenyan, Matteo Lisi, John A. Greenwood et al. 13 citations
Visual hallucinations can be simple (flashes, patterns) or complex (objects, scenes). Two experimental methods—Ganzflicker (high-frequency flickering light) and Ganzfeld (uniform visual field deprivation)—induced hallucinations in healthy participants. Simple hallucinations were more common than complex ones under both conditions. Ganzflicker produced more simple hallucinations than Ganzfeld, while complex hallucinations occurred at similar rates. Consequently, the proportion of complex hallucinations was higher during Ganzfeld. Correlations in hallucination frequency and duration across conditions suggest shared mechanisms, likely involving visual cortex excitability. Simple hallucinations may stem from heightened bottom-up input, especially in Ganzflicker, while complex hallucinations may rely on top-down processes less influenced by visual stimulation.