What happened
Researchers found that people with stronger natural visual imagination see more complex, realistic scenes in Ganzflicker hallucinations (a rapidly flashing red-and-black light that triggers visual experiences), while people with weaker visual imagination see only simple geometric patterns. This suggests the brain's ability to generate internal images — a trait that varies widely between individuals — directly determines what kinds of visual experiences it can produce, even when those experiences are triggered by external stimulation.
Why it matters
This is the first large-scale evidence that individual differences in how vividly people can imagine things in their mind predicts what they actually perceive in altered states, which challenges the assumption that hallucinations are random noise and instead suggests they're shaped by stable features of each person's visual system.