Abstract
With the recent identification of aphantasia (no mind’s eye) and hyperphantasia (extremely vivid mind’s eye), mental imagery “extremes” research has become increasingly popular. One major methodological issue is there is no defined criteria for typical and atypical self-reports of imagery, and while the Vividness of Visual Imagery Questionnaire (VVIQ) is widely used, it was not developed to classify imagery extremes. In the current study, we established a short interview method to categorize individuals by visual imagery ability, and compared this to VVIQ cut-offs (<=23: aphantasia, >=75: hyperphantasia). Interestingly, many individuals who thought they had aphantasia (based on VVIQ scores) experienced imagery. The interview method revealed 4 distinct imagery categories: aphantasia, hypophantasia (low imagery), typical imagery, and hyperphantasia. We recruited 15 participants from each category (internet volunteers and students) to perform a test battery measuring imagery projection ability (prophantasia), visual working memory (VWM) precision and strategies, imagery priming, pseudo-hallucination prevalence and features (Ganzflicker), and imagery interference with memory. Only prophantasia differences, VWM strategy differences, and pseudo-hallucination complexity differences were diagnostic of extreme imagery. 78% of hyperphantasics and 33% of those with typical imagery have prophantasia, whereas aphantasics and hypophantasics do not experience prophantasia. Differences in dominant VWM strategy (visual versus spatial) are driven by individuals with hyperphantasia (visual) and aphantasia (spatial), but not typical imagery or hypophantasia (who use visuospatial strategies). Delving into Ganzflicker, aphantasics do not experience complex pseudo-hallucinations, whereas >50% of hyperphantasics do, and those with typical imagery and hypophantasia share a similar (low) likelihood of having complex experiences. If individuals are grouped based on VVIQ cut-off convention, these nuances in results are overlooked. Bayesian correlations and contingency tables tests corroborated these differences. It is therefore important to recruit a wide range of imagery abilities for extreme imagery research, and distinguish low imagery (hypophantasia) from no imagery (aphantasia).