Evidence for face pareidolia in rhesus monkeys.

Abstract

In everyday life we have a tendency to see faces in non-face objects; a famous example is the face of a nondescript man on the surface of mars. Although these misperceptions are often very compelling, it is not known whether "face pareidolia" is unique to humans or whether it is an experience shared with other animals. Like humans, rhesus monkeys have a functionally defined face-processing system, comprised of multiple interconnected areas distributed along the ventral visual pathway. In this study, we reasoned that the potential analogy between this system and our own made it likely that rhesus monkeys also experience face pareidolia. To test this hypothesis, we first collected 15 examples of face pareidolia from the public domain together with objects matched for object-content. An additional 15 photographs were taken of unfamiliar rhesus monkey faces. All possible pairs of these 45 images were shown to 5 male rhesus monkeys, one at a time for 4 seconds, in a visual paired comparison task. We collected two dependent variables (the total amount of time spent looking at each image; first fixation in each trial). In addition to replicating the common observation that rhesus monkeys look longer at face stimuli than other kinds of objects, we also found clear evidence that monkeys look for longer periods of time (and first) at examples of face pareidolia than at object-matched control images. We repeated this experiment with the images inverted and collected independent data from human participants (N = 10) who were asked to rate how face-like each image was on a 200-point scale. Overall, our results indicate that monkeys also see face configurations in non-face objects and, as such, provide the first compelling evidence of face pareidolia in any species other than our own. Meeting abstract presented at VSS 2017