Visual Imagery Vividness Predicts the Complexity of Induced Hallucinations

The current study utilizes the Ganzflicker paradigm—a flickering stimulus that induces visual hallucinations—to provide insight into the internally-generated visual experiences that correlate with individual differences in visual imagery. Here, we analyzed rich narrative descriptions of Ganzflicker hallucinations from 4,365 participants using natural language processing, sensorimotor norms, and AI visualizations. We find that overall perceptual richness and visual detail in descriptions increase with imagery vividness. Examining the specific content of these descriptions reveals that vivid imagers report more face and hand-related content than those with weaker imagery. Exploratory AI-generated visualizations of these descriptions provide additional insights, as those with weak imagery report patterns of simple visual features, like colors and geometric forms, while strong imagers’ hallucinations are filled with complex real-world stimuli. These findings suggest imagery differences may lie not in early visual processing but in the integration of basic visual features into complex object- and scene-level representations.