A shared mechanism for facial expression in human faces and face pareidolia

Abstract

Facial expressions are vital for social communication, yet the underlying mechanisms are still being discovered. Illusory faces perceived in objects (face pareidolia) are errors of face detection that share some neural mechanisms with human face processing. However, it is unknown whether expression in illusory faces engages the same mechanisms as human faces. Here, using a serial dependence paradigm, we investigated whether illusory and human faces share a common expression mechanism. First, we found that images of face pareidolia are reliably rated for expression, within and between observers, despite varying greatly in visual features. Second, they exhibit positive serial dependence for perceived facial expression, meaning an illusory face (happy or angry) is perceived as more similar in expression to the preceding one, just as seen for human faces. This suggests illusory and human faces engage similar mechanisms of temporal continuity. Third, we found robust cross-domain serial dependence of perceived expression between illusory and human faces when they were interleaved, with serial effects larger when illusory faces preceded human faces than the reverse. Together, the results support a shared mechanism for facial expression between human faces and illusory faces and suggest that expression processing is not tightly bound to human facial features.

Objects that induce face pareidolia are prioritized by the visual system

“…Interestingly, these early signals seem to be more similar to those brain responses conveying information about real faces and driven by low‐level visual features, such as high‐contrast and low‐spatial frequency components of face configuration (Wardle et al, 2017b). Also, results from recent gaze cueing and cross‐adaptation studies indicate that sensory mechanisms recruited for viewing human faces may overlap with those recruited for viewing pareidolia faces (Alais et al, 2021; Palmer & Clifford, 2020; Takahashi & Watanabe, 2013). Together, these findings suggest that the mechanisms involved in the early stages of visual processing might treat face pareidolia stimuli like real faces.…”

Assessing the perception of face pareidolia in children (Homo sapiens), rhesus monkeys (Macaca mulatta), and capuchin monkeys (Sapajus apella).

“…In another experiment, humans used a 200-point slider scale and consistently rated the illusory face images as more "face-like" than control images (Taubert, Wardle, et al, 2017). Recent experiments have also shown similarities in the processing of social information from real and illusory faces (Alais et al, 2021;Palmer & Clifford, 2020;Wardle et al, 2022). A few experiments have studied whether this illusion is present in young children or infants, using looking-time measures and categorization tasks (Beran et al, 2017;Kato & Mugitani, 2015;Kobayashi et al, 2012).…”

I See Faces! A Review on Face Perception and Attractiveness with a Prosthodontic Peek at Cognitive Psychology

“…7 Face pareidolia is diverse among the population. [7][8][9][10] People with religious and paranormal beliefs are more likely to experience face pareidolia, as they are more inclined to report meaningful pattens (a face or a word) out of meaningless input. 11 Also, females experience face pareidolia more than males.…”