Face Perception and Pareidolia Production in Patients With Parkinson's Disease.

Nicole Göbel,Andreas Binder,Matthias Oechsner,René M Müri,Nathalie Hollenstein,Prabitha Urwyler,Jens Carsten Möller,Jörg Ide,Dario Cazzoli

doi:10.3389/fneur.2021.669691

Abstract

In Parkinson's disease (PD) patients, visual misperceptions are a major problem within the non-motor symptoms. Pareidolia, i.e., the tendency to perceive a specific, meaningful image in an ambiguous visual pattern, is a phenomenon that occurs also in healthy subjects. Literature suggests that the perception of face pareidolia may be increased in patients with neurodegenerative diseases. We aimed to examine, within the same experiment, face perception and the production of face pareidolia in PD patients and healthy controls (HC). Thirty participants (15 PD patients and 15 HC) were presented with 47 naturalistic photographs in which faces were embedded or not. The likelihood to perceive the embedded faces was modified by manipulating their transparency. Participants were asked to decide for each photograph whether a face was embedded or not. We found that PD patients were significantly less likely to recognize embedded faces than controls. However, PD patients also perceived faces significantly more often in locations where none were actually present than controls. Linear regression analyses showed that gender, age, hallucinations, and Multiple-Choice Vocabulary Intelligence Test (MWT) score were significant predictors of face pareidolia production in PD patients. Montreal Cognitive Assessment (MoCA) was a significant predictor for pareidolia production in PD patients in trials in which a face was embedded in another region [F(1, 13) = 24.4, p = <0.001]. We conclude that our new embedded faces paradigm is a useful tool to distinguish face perception performance between HC and PD patients. Furthermore, we speculate that our results observed in PD patients rely on disturbed interactions between the Dorsal (DAN) and Ventral Attention Networks (VAN). In photographs in which a face is present, the VAN may detect this as a behaviourally relevant stimulus. However, due to the deficient communication with the DAN in PD patients, the DAN would not direct attention to the correct location, identifying a face at a location where actually none is present.

Highlights

Illusions and hallucinations are a major problem within non-motor symptoms of Parkinson’s disease (PD)
We developed the so-called embedded face paradigm using complex visual naturalistic photographs, in which faces were embedded or not
The predictors of pareidolia production we found were based on the variables gender, age, presence of hallucinations, MWT score, Montreal Cognitive Assessment (MoCA) score, and presence of deep brain stimulators (DBS), which explained 78.1% of the variance

Summary

Introduction

Illusions (misperceptions of real stimuli) and hallucinations (aberrant perceptions) are a major problem within non-motor symptoms of Parkinson’s disease (PD). They occur in more than half of all patients with advanced disease [1,2,3,4,5]. Older patients with slight decline of cognitive function were at higher risk of developing hallucinations under treatment [6]. In 35-40% of drug-naive “de novo” PD patients, minor hallucinations were reported [7] with gray matter loss in MRI being a risk factor [8]. In visual hallucinations and illusions, most common “people” are reported [10]. PD patients realize that they are hallucinating, though patients with dementia may lose this insight [3]

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