The Ganzflicker experience: A window into the mind's eye

The mind's eye is an elusive subjective experience; as such, most of us are unaware that there is more than one way to imagine the sensory world. People who have no mind's eye (aphantasia) must rely on non-sensory imagination (symbols, words) to simulate the world, whereas people who have an extremely vivid mind's eye (hyperphantasia) may get lost in visual fantasies on a daily basis. Imagery is now thought to be a spectrum, with different abilities offering different advantages and disadvantages in daily life and across the lifespan. An elegant method we adapted as a window to the rich individual differences of the mind's eye is "Ganzflicker", a rhythmic alternation of colors that can elicit immediate and vivid pseudo-hallucinations. Over the past year, over 200 individual Ganzflicker experiences were collected from people across the spectrum of imagery abilities, both from anonymous internet volunteers and a student sample. First, results point toward a bimodal distribution of imagery ability, with aphantasia (no-to-low imagery) as a distinct spectrum from (moderate-to-vivid) imagery. Bayesian analyses provide extremely strong evidence that people with aphantasia are less prone to pseudo-hallucinations compared to people with imagery. Among those who have visuals, people with imagery see more vivid and complex pseudo-hallucinations, and experience more altered states of consciousness, compared to people with aphantasia. We propose that aphantasia may provide a buffer against induced anomalous percepts. This study has important implications for understanding pathological hallucinations, which are unpredictable and debilitating to normal life.