/ From the archive · 2024
Flicker beats blank fields at triggering simple hallucinations
A study co-authored by Jeremy Skipper compares two lab techniques for inducing visual hallucinations, Ganzflicker and Ganzfeld.
Hallucinations can be simple or complex, and both can be induced in the lab: Ganzflicker uses a high-frequency, eyes-open flicker, while Ganzfeld relies on perceptual deprivation. The team measured how often people hallucinated and how complex the experiences were, using button presses, drawings, interviews and questionnaires.
Simple hallucinations were more common than complex ones under both techniques. Ganzflicker was more effective at eliciting simple hallucinations, while complex hallucinations were equivalent across the two. Hallucination frequency and time spent hallucinating correlated across conditions, which the authors take as a sign of a shared low-level mechanism, such as excitability of visual cortex.
Source: doi:10.1038/s41598-024-52372-1
Relevant to: Principles of Cognition, Lecture 6: The Neuroscience of Consciousness (today)
Jeremy Skipper gives today's Principles of Cognition lecture, The Neuroscience of Consciousness (Lecture 6), and is Professor of Cognitive Neuroscience in Experimental Psychology, UCL.