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

Königsmark, Varg T.; Bergmann, Johanna; Reeder, Reshanne

doi:10.1016/j.cortex.2021.05.007

Cited by 30 publications

(39 citation statements)

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“…"Ganzflicker" is a full-field, rhythmic visual flicker -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 reported susceptibility to visual pseudo-hallucinations after viewing 10 minutes of continuous red-and-black Ganzflicker at 7.5 Hz. In a post-experience questionnaire of 204 responses, we found that the reported complexity and vividness of pseudo-hallucinations is related to visual mental imagery vividness.…”

mentioning

confidence: 83%

“…Stimuli were the same as in the previous study (Königsmark et al, 2021). To summarize, the Ganzflicker was a full-screen red-and-black visual flicker at 7.5 Hz (colors al-…”

Section: Stimulimentioning

confidence: 99%

“…Responses on the post-Ganzflicker questionnaire concerning different features of pseudo-hallucinations were coded using the same method as described in the previous study (Königsmark et al, 2021). In summary, participants could select multiple responses for all questions, and we took the maximum value the participant selected (e.g., if a participant reported seeing both simple shapes and complex objects, we coded the participant as having seen complex objects).…”

Section: Coding Subjective Responsesmentioning

confidence: 99%

“…As a result, most people with aphantasia go their lives never knowing their internal representations of the world are different from anyone else's (Zeman et al, 2015). However, Ganzflicker appears to bring imagery out into the external environment, providing a striking example of the different subjective experiences people with aphantasia and imagery can have (Königsmark et al, 2021).…”

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confidence: 99%

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Ganzflicker Reveals the Complex Relationship Between Visual Mental Imagery and Pseudo-Hallucinatory Experiences: A Replication and Expansion

Reeder

2022

Collabra: Psychology

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Rhythmic visual flicker is known to elicit pseudo-hallucinations, making it an up-and-coming method to investigate anomalous perceptual experiences without pharmaceutical intervention. Ganzflicker is a full-screen visual flicker that can be experienced online. In the first exploratory Ganzflicker paper (N = 204), we investigated whether people with different self-reported visual mental imagery abilities report different visual experiences in the Ganzflicker. Results showed that people with no-to-low imagery (aphantasia distribution) were much less likely to experience complex and vivid pseudo-hallucinations compared to people with moderate-to-vivid imagery (imagery distribution). In this follow-up, I collected data from 6664 individuals from around the world, replicated the main results of the previous study, and additionally found that people from the imagery distribution report more frequent pseudo-hallucinations for a longer duration than people from the aphantasia distribution. I also conducted new analyses across individual imagery vividness ratings. This revealed a dramatic increase in susceptibility to pseudo-hallucinations from reports of “no imagery” to “low imagery vividness” within the aphantasia distribution. There is a positive linear relationship between imagery vividness and pseudo-hallucination vividness, whereas the relationship between imagery vividness and pseudo-hallucination complexity is categorical, as indicated by a jump in the likelihood to experience complex pseudo-hallucinations from the aphantasia distribution to the imagery distribution with no evidence for within-distribution variations. Finally, word cloud analyses of written descriptions of Ganzflicker experiences revealed unique language used by individuals from each distribution. In sum, Ganzflicker is an accessible, efficient, and effective method of investigating multiple aspects of anomalous perceptual experiences in people with different mental imagery abilities.

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mentioning

confidence: 83%

“…Stimuli were the same as in the previous study (Königsmark et al, 2021). To summarize, the Ganzflicker was a full-screen red-and-black visual flicker at 7.5 Hz (colors al-…”

Section: Stimulimentioning

confidence: 99%

Section: Coding Subjective Responsesmentioning

confidence: 99%

mentioning

confidence: 99%

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Ganzflicker Reveals the Complex Relationship Between Visual Mental Imagery and Pseudo-Hallucinatory Experiences: A Replication and Expansion

Reeder

2022

Collabra: Psychology

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“…(Walter & Walter, 1949, p. 59) and also investigated the somatic, mental and emotional changes that could be induced in participants by different rates of visual flicker (Walter, 1963). In addition, he also described individual differences in whether visual or non-visual sensations arose during flicker depending on the participant's propensity for visual imagery (Walter, 1963;Walter & Walter, 1949), a phenomenon currently being investigated under the name of Ganzflicker (Königsmark et al, 2021).…”

Section: Flickers Of Understandingmentioning

confidence: 99%

Forgotten rhythms? Revisiting the first evidence for rhythms in cognition

Quigley

2021

Eur J of Neuroscience

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Practically every neuroscientist knows that human brain rhythms were first recorded in the 1920s by Hans Berger, who coined the term ‘alpha waves’ for the regular activity of around 10 cycles per second that was clearly visible in many of his recordings. Almost 100 years later, alpha rhythms are still the subject of active investigation and continue to intrigue researchers. What we have perhaps forgotten though, is the clever experimentation that was carried out during the first decades of electroencephalogram (EEG) research, often using sophisticated, custom‐made analysis and stimulation devices. Here, I review selected findings from the early EEG literature regarding the character, origin, and meaning of human brain rhythms, beginning with Berger's publications and then focusing on the use of regular visual stimulation as a tool to understand intrinsic brain rhythms. It is clear that many of these findings are still relevant to open questions about the role of rhythmic brain activity. In addition, they also contain some general lessons for contemporary neuroscientists, meaning that there is great value in looking back at these forgotten publications.

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Measuring imagery strength in schizophrenia: no evidence of enhanced mental imagery priming

Wagner¹,

Monzel

2023

Brain and Behavior

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IntroductionRecent research shows ambivalent results regarding the relationship between mental imagery and schizophrenia. The role of voluntary visual imagery in schizophrenic hallucinations remains unclear. The aim of the study was to investigate the association between visual imagery, schizophrenia, and the occurrence of schizophrenic hallucinations using an objective visual imagery task.MethodsThe sample consisted of 16 participants with schizophrenia (59.1% female; MAge = 45.55) and 44 participants without schizophrenia (62.5% female; MAge = 43.94). Visual imagery was measured using the Vividness of Visual Imagery Questionnaire (VVIQ) as well as the well‐validated Binocular Rivalry Task (BRT). Occurrences of hallucinations were assessed using the Launay–Slade Hallucination Scale.ResultsParticipants with schizophrenia showed more hallucinatory experiences but did not score higher on either the VVIQ or the BRT than participants without schizophrenia. A correlation between the VVIQ and the BRT was found, validating the measurement of visual imagery and enabling the interpretation that visual imagery vividness is not enhanced in people with schizophrenia.ConclusionThe association between mental imagery vividness and schizophrenia found in previous studies may be based on other facets of mental imagery than visual imagery.

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

Cited by 30 publications

References 58 publications

Ganzflicker Reveals the Complex Relationship Between Visual Mental Imagery and Pseudo-Hallucinatory Experiences: A Replication and Expansion

Ganzflicker Reveals the Complex Relationship Between Visual Mental Imagery and Pseudo-Hallucinatory Experiences: A Replication and Expansion

Forgotten rhythms? Revisiting the first evidence for rhythms in cognition

Measuring imagery strength in schizophrenia: no evidence of enhanced mental imagery priming

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