Illusory Faces Elicit Similar Responses as Real Faces

Article: So happy to see you: our brains respond emotionally to faces we find in inanimate objects, study reveals
Source: The Guardian, via The Scientist  and Technology Networks
Published: July 6, 2021
Article: A man in the moon: why our brains see human faces everywhere
Source: University of Sydney (Australia), via ScienceAlert  and ScienceDaily
Published: July 7, 2021
Article: Here's Why We Tend to See Faces Everywhere We Look, According to Science
Source: ScienceAlert
Published: July 9, 2021

Bee orchid (Ophrys apifera), with multiple interpretations for eyes

Face pareidolia, the perception of illusory faces in inanimate objects, lies at the intersection between optical illusions and facial recognition. Although technically an error in visual processing, the ability to quickly perceive faces with a crude template of two eyes, a nose, and a mouth—and the emotions they express—is an evolutionary benefit for judging friend or foe, a side effect that is so common that we simply accept it as normal. Neuroscientists in Australia wanted to study the psychology behind the phenomenon, especially as it pertains to the perception of emotions. “We know these objects are not truly faces, yet the perception of a face lingers,” the first author of the study explained, “We end up with something strange: a parallel experience that it is both a compelling face and an object. Two things at once. The first impression of a face does not give way to the second perception of an object.” Their study asked 17 participants to view sequences of dozens of real and illusory faces and rate the perceived emotion on a scale from happy to angry. The results showed that perception of facial expression was consistent across observers, despite variations in visual features. Secondly, the expression on prior faces influenced the perception of subsequent faces. For example, seeing happy faces caused the viewer to more likely perceive the next face as happier. Lastly, this bias was observed even when the real faces and illusory faces were interleaved in the sequence. Such a "cross-over" condition revealed that rather than being discarded as false detections, analysis of facial expression applied to the illusory faces in the same way as for real faces. The lead researcher concluded, “When objects look compellingly face-like, it is more than an interpretation: they really are driving your brain’s face detection network. And that scowl, or smile; that’s your brain’s facial expression system at work. For the brain, fake or real, faces are all processed the same way.”

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Alais D, Xu Y, Wardle SG, et al. "A shared mechanism for facial expression in human faces and face pareidolia." Proceedings of the Royal Society B.  7 July 2021. https://doi.org/10.1098/rspb.2021.0966