“Ganzflicker” is a full-field, rhythmic visual flicker, using a technique that is known to elicit pseudo-hallucinations and altered states of consciousness (Allefeld et al., 2011; Bartossek et al., 2021; Schwartzman et al., 2019; Sumich et al., 2018). In a recently published study (Königsmark et al., 2021), we found individual differences in the likelihood of reporting visual pseudo-hallucinations, as well as different features of pseudo-hallucinations, while observing 10 minutes of continuous red-and-black flicker at 7.5 Hz, termed “Ganzflicker”. In a post-experience questionnaire of 204 responses, we found extremely strong evidence that the likelihood of experiencing complex and vivid pseudo-hallucinations is related to self-reported visual mental imagery vividness. Specifically, people with no visual imagery (or, at most, dim or vague imagery; aphantasia distribution) are much less likely to experience vivid and complex pseudo-hallucinations than people with moderate-to-vivid visual imagery (imagery distribution).In this commentary, I present an updated analysis of Ganzflicker questionnaire responses, due to a significant increase in the number of new data points collected (N = 5553), influenced by a recent article published in the popular media (Reeder, n.d.). In this new analysis, environmental variables were found to play a role in pseudo-hallucination proneness, particularly concerning whether participants viewed the Ganzflicker on a computer or mobile phone. This suggests that the level of visual immersion increases the likelihood of anomalous perceptual experiences. I also found extremely strong evidence that pseudo-hallucination proneness differs between people with a completely blind mind’s eye (imagery vividness rating = 0) compared to people with imagery, regardless of imagery vividness rating (ratings 1-10). This suggests that there are sometimes important distinctions between having low imagery and no imagery. I additionally found differences in the reported complexity and vividness of pseudo-hallucinations between people belonging to the aphantasia distribution (vividness ratings from 0-3) and imagery distribution (vividness ratings from 4-10), replicating previous results. Finally, I found that people belonging to the imagery distribution are more likely to see more frequent pseudo-hallucinations for a longer duration than people from the aphantasia distribution. In sum, I replicated the core result of the previous paper in a dataset that is orders of magnitude larger than the original.
The Ganzflicker Experience: Rhythmic visual flicker induces complex illusions in people with visual imagery but not aphantasia