The phenomenology of pareidolia in healthy subjects and patients with left- or right-hemispheric stroke

M Camenzind; N Göbel; A K Eberhard-Moscicka; S E J Knobel; H Hegi; M Single; B C Kaufmann; R Schumacher; T Nyffeler; T Nef; R M Müri

doi:10.1016/j.heliyon.2024.e27414

The phenomenology of pareidolia in healthy subjects and patients with left- or right-hemispheric stroke

Heliyon. 2024 Feb 29;10(5):e27414. doi: 10.1016/j.heliyon.2024.e27414. eCollection 2024 Mar 15.

Authors

M Camenzind¹, N Göbel^{1

2}, A K Eberhard-Moscicka^{1

3

4}, S E J Knobel⁵, H Hegi⁵, M Single⁵, B C Kaufmann⁶, R Schumacher^{1

3}, T Nyffeler⁶, T Nef^{3

5}, R M Müri^{1

3

5}

Affiliations

¹ Perception and Eye Movement Laboratory, Departments of Neurology and BioMedical Research, Inselspital, Bern University Hospital and University of Bern, Switzerland.
² Research and Analysis Services, University Hospital Basel and University of Basel, Basel, Switzerland.
³ Department of Neurology, Inselspital, Bern University Hospital, University of Bern, Switzerland.
⁴ Department of Psychology, University of Bern, Bern, Switzerland.
⁵ Gerontechnology and Rehabilitation Group, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.
⁶ Neurocenter, Luzerner Kantonsspital, Lucerne, Switzerland.

Abstract

Pareidolia are perceptions of recognizable images or meaningful patterns where none exist. In recent years, this phenomenon has been increasingly studied in healthy subjects and patients with neurological or psychiatric diseases. The current study examined pareidolia production in a group of 53 stroke patients and 82 neurologically healthy controls who performed a natural images task. We found a significant reduction of absolute pareidolia production in left- and right-hemispheric stroke patients, with right-hemispheric patients producing overall fewest pareidolic output. Responses were categorized into 28 distinct categories, with 'Animal', 'Human', 'Face', and 'Body parts' being the most common, accounting for 72% of all pareidolia. Regarding the percentages of the different categories of pareidolia, we found a significant reduction for the percentage of "Body parts" pareidolia in the left-hemispheric patient group as compared to the control group, while the percentage of this pareidolia type was not significantly reduced in right-hemispheric patients compared to healthy controls. These results support the hypothesis that pareidolia production may be influenced by local-global visual processing with the left hemisphere being involved in local and detailed analytical visual processing to a greater extent. As such, a lesion to the right hemisphere, that is believed to be critical for global visual processing, might explain the overall fewest pareidolic output produced by the right-hemispheric patients.

Keywords: Hemispheric stroke; Natural images; Pareidolia; Visual illusions; Visual processing.