Visual imagery capacity shaped what participants saw during Ganzflicker hallucinations
A rapidly alternating red-and-black Ganzflicker display can push the visual system into producing hallucination-like experiences, and the content of those experiences was not random. In a study using free-text descriptions from more than 4,000 participants, stronger visual imagers tended to report complex, naturalistic scenes, while weaker imagers more often described simple geometric patterns. The result gives a concrete behavioral readout of a long-standing question in consciousness science: whether differences in inner imagery are tied not just to how vivid a mental image feels, but to what kind of content the brain can generate at all.
The analysis moved beyond traditional rating scales and into language itself. Investigators applied natural language processing to the descriptions people wrote after viewing the flicker stimulus, then used topic modeling to sort the hallucination reports into recurring content patterns. The distribution was strikingly orderly. Participants with stronger imagery were more likely to use words that mapped onto faces, objects, scenes, and other rich perceptual forms. Participants with weaker imagery drifted toward reports of simple geometric shapes, an output that fits a more stripped-down visual experience.
A single stimulus revealed a split in internal visual construction.
Language exposed the structure of internally generated vision
What makes this result especially useful is the method. Free-text reports are messy by design, yet they preserve the details that simple checkboxes often flatten away. Here, language served as a window into the content of hallucinations induced by Ganzflicker, and the text analysis separated complex, naturalistic imagery from more elementary visual forms. That distinction matters because it suggests that imagery ability is not only a matter of intensity. It may shape the representational architecture of internally generated vision, determining whether the brain assembles a face-like or scene-like percept, or stops earlier at angles, lines, and repeating patterns.
The study also went a step further by examining the words participants used in relation to crowd-sourced sensorimotor norms. Stronger imagers produced language with richer perceptual associations, which implies that their descriptions carried more sensorimotor weight. In plain clinical terms, the words people chose tracked with the sensory richness of the hallucination content itself. That is important because it links subjective experience to measurable semantic structure, offering a bridge between introspective reports and a computational analysis of perception.
The biological interpretation is plausible even if the study was not designed to map circuitry directly. Differences in imagery capacity may reflect variation in coordination between early visual areas and higher-order regions involved in internally generated perception. When that coordination is robust, the visual system may recruit richer object and scene representations, producing hallucinations with more naturalistic content. When it is weaker, the system may generate simpler patterned activity instead, leaving the person with stripes, shapes, or abstract forms rather than anything recognizably face-like.
What the imagery spectrum may reveal about visual system organization
The findings also sharpen a broader idea in cognitive neuroscience: the imagery spectrum may represent a real axis of visual system organization, not just a difference in confidence or descriptive style. People who experience vivid mental images appear to draw from a more elaborated internal representational pool, and Ganzflicker appears capable of exposing that difference in real time. The work therefore supports a model in which hallucination content is constrained by the same neural machinery that supports voluntary mental imagery.
For clinicians and scientists, the practical value lies in the separation of content from intensity. Many studies ask whether a stimulus induces hallucinations at all. This one asks what form those hallucinations take, and the answer tracks with individual imagery phenotype. A face, a scene, or a complex naturalistic object implies a different level of visual synthesis than a purely geometric pattern. Those differences could help future work define subtypes within internally generated visual experience, especially in studies of consciousness, perceptual inference, and imagery-related traits.
The data also show why natural language processing may become a useful tool in neurocognitive research. Human report remains central when studying subjective phenomena, but large text datasets can now be analyzed systematically rather than anecdotally. By extracting recurring themes from thousands of descriptions, the investigators captured structure that would be difficult to detect by manual reading alone. The method does not replace phenomenology; it gives phenomenology a scalable analytical layer.
Why the content of hallucinations matters
The most direct takeaway is simple: visual imagery capacity predicted the content of Ganzflicker-induced hallucinations. Strong imagers described richer, more naturalistic experiences, while weak imagers described more elementary geometric forms. In a field where internal experience can be notoriously hard to quantify, that pattern offers a tangible way to connect brain function, language, and perception.
The study leaves important mechanistic questions open. It does not directly measure neural connectivity, and it does not establish how the imagery spectrum is implemented in cortical networks. Even so, the pattern fits a coherent account in which top-down coordination between early visual cortex and higher-order systems shapes the structure of generated perception. Future work will need to determine whether the same relationship appears across other hallucination paradigms and whether imagery phenotype can predict content in clinical settings as well as in experimental ones.
For now, the result is clear enough to stand on its own: the brain does not generate all hallucinations in the same way, and the content of those experiences appears to depend on how a person’s visual imagery system is organized.