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The Ganzflicker experience: High probability of seeing vivid and complex pseudo-hallucinations with imagery but not aphantasia

DOI: 10.1016/j.cortex.2021.05.007
Königsmark, V. T., Bergmann, J., & Reeder, R. R. (2021). The ganzflicker experience: high probability of seeing vivid and complex pseudo-hallucinations with imagery but not aphantasia. Cortex, 141, 522–534. doi:10.1016/j.cortex.2021.05.007

Abstract

There are considerable individual differences in visual mental imagery ability across the general population, including a "blind mind's eye", or aphantasia. Recent studies have shown that imagery is linked to differences in perception in the healthy population, and clinical work has found a connection between imagery and hallucinatory experiences in neurological disorders. However, whether imagery ability is associated with anomalous perception-including hallucinations-in the general population remains unclear. In the current study, we explored the relationship between imagery ability and the anomalous perception of pseudo-hallucinations (PH) using rhythmic flicker stimulation ("Ganzflicker"). Specifically, we investigated whether the ability to generate voluntary imagery is associated with susceptibility to flicker-induced PH. We additionally explored individual differences in observed features of PH. We recruited a sample of people with aphantasia (aphants) and imagery (imagers) to view a constant red-and-black flicker for approximately 10 min. We found that imagers were more susceptible to PH, and saw more complex and vivid PH, compared to aphants. This study provides the first evidence that the ability to generate visual imagery increases the likelihood of experiencing complex and vivid anomalous percepts.

Authors

  • Varg T. Königsmark1
  • Johanna Bergmann4
  • Reshanne R. Reeder5

Exploring Visual Imagery and Perception: A Study on Aphantasia and Pseudo-Hallucinations

Overview/Introduction

Visual mental imagery, or the ability to visualize images in the "mind's eye," varies greatly among individuals. Some people experience aphantasia, a condition where they cannot visualize images at all. This study investigates whether the ability to generate visual imagery is linked to experiencing pseudo-hallucinations (PH), which are vivid and complex visual experiences induced by specific stimuli. The research aims to understand how imagery ability affects susceptibility to these experiences.

Methodology

  • Participants: The study involved two groups: individuals with aphantasia (aphants) and those with typical imagery abilities (imagers).
  • Stimulus: Participants were exposed to a "Ganzflicker" experience, which involves viewing a rhythmic red-and-black flicker for about 10 minutes.
  • Data Collection: Participants rated the vividness and complexity of any visual experiences they had during the flicker. This was done using an online questionnaire immediately after the experiment.

Key Findings

  • Imagery and PH Susceptibility: Imagers were more likely to experience pseudo-hallucinations compared to aphants.
  • Complexity and Vividness: Imagers reported more complex and vivid PH, seeing detailed objects and environments, whereas aphants mostly saw simple shapes or patterns.
  • Common Features: Both groups reported that PH emerged quickly, occurred frequently, and lasted for more than a second.

Implications

  • Understanding Perception: This study highlights how individual differences in mental imagery can influence the perception of visual stimuli. It suggests that people with stronger imagery abilities are more prone to experiencing vivid visual phenomena.
  • Potential Applications: These findings could inform therapeutic approaches for conditions involving hallucinations or intrusive imagery, by considering individual differences in imagery ability.

Limitations

  • Subjective Reports: The study relied on participants' subjective experiences, which may vary in accuracy. Future research could use objective measures, such as eye tracking, to validate these findings.
  • Uncontrolled Environment: The online nature of the study meant that participants' viewing conditions varied, which could have influenced their experiences.
In summary, this research provides new insights into how visual imagery ability affects the perception of pseudo-hallucinations, with imagers experiencing more vivid and complex visual phenomena than aphants. Further studies are needed to explore these findings in controlled settings and to investigate their implications for clinical practice.