Face Pareidolia in the Rhesus Monkey

• Published in: Current biology 2017-08, Vol.27 (16), p.2505-2509.e2
• Main Authors: Taubert, Jessica, Wardle, Susan G., Flessert, Molly, Leopold, David A., Ungerleider, Leslie G.
• Format: Article
• Language: English
• Subjects: Animals; Eye Movements; face detection; face perception; Facial Recognition; Female; Humans; Illusions - physiology; Macaca mulatta - physiology; Male; monkey behavior; Pattern Recognition, Visual; visual preference; Young Adult
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2017.06.075

Face perception in humans and nonhuman primates is rapid and accurate [1–4]. In the human brain, a network of visual-processing regions is specialized for faces [5–7]. Although face processing is a priority of the primate visual system, face detection is not infallible. Face pareidolia is the compelling illusion of perceiving facial features on inanimate objects, such as the illusory face on the surface of the moon. Although face pareidolia is commonly experienced by humans, its presence in other species is unknown. Here we provide evidence for face pareidolia in a species known to possess a complex face-processing system [8–10]: the rhesus monkey (Macaca mulatta). In a visual preference task [11, 12], monkeys looked longer at photographs of objects that elicited face pareidolia in human observers than at photographs of similar objects that did not elicit illusory faces. Examination of eye movements revealed that monkeys fixated the illusory internal facial features in a pattern consistent with how they view photographs of faces [13]. Although the specialized response to faces observed in humans [1, 3, 5–7, 14] is often argued to be continuous across primates [4, 15], it was previously unclear whether face pareidolia arose from a uniquely human capacity. For example, pareidolia could be a product of the human aptitude for perceptual abstraction or result from frequent exposure to cartoons and illustrations that anthropomorphize inanimate objects. Instead, our results indicate that the perception of illusory facial features on inanimate objects is driven by a broadly tuned face-detection mechanism that we share with other species. [Display omitted] •Face pareidolia is not a uniquely human-specific trait or experience•Eye movements reveal rhesus monkeys perceive illusory faces on inanimate objects•Monkeys consistently fixate on the illusory internal features (eyes and mouth)•Pareidolia is driven by a mechanism highly tolerant of variation in visual features Taubert et al. provide the first empirical evidence of face pareidolia in any species other than our own. The data show that, like humans, rhesus monkeys spontaneously perceive illusory facial structure on inanimate objects. This suggests that both species share a broadly tuned face detection system robust to highly variable visual properties.