Preliminary evidence of an increased susceptibility to face pareidolia in postpartum women

Abstract

As primates, we are hypersensitive to faces and face-like patterns in the visual environment, hence we often perceive illusory faces in otherwise inanimate objects, such as burnt pieces of toast and the surface of the moon. Although this phenomenon, known as face pareidolia, is a common experience, it is unknown whether our susceptibility to face pareidolia is static across our lifespan or what factors would cause it to change. Given the evidence that behaviour towards face stimuli is modulated by the neuropeptide oxytocin (OT), we reasoned that participants in stages of life associated with high levels of endogenous OT might be more susceptible to face pareidolia than participants in other stages of life. We tested this hypothesis by assessing pareidolia susceptibility in two groups of women; pregnant women (low endogenous OT) and postpartum women (high endogenous OT). We found evidence that postpartum women report seeing face pareidolia more easily than women who are currently pregnant. These data, collected online, suggest that our sensitivity to face-like patterns is not fixed and may change throughout adulthood, providing a crucial proof of concept that requires further research.

A behavioral advantage for the face pareidolia illusion in peripheral vision

“…1 B). This nested design has been exploited in previous studies of ambient face pareidolia because it means any differences in the behavioral or neural correlates are driven by the presence of illusory facial features 7 , 9 – 11 , 14 , 19 , 21 , 23 , 24 , 36 . Thus, the current results suggest that the advantage for faces in the fast saccadic choice paradigm is supported, at least in part, but the visual information that real and illusory faces share in common.…”

“…A number of researchers have previously described variation in the strength of the illusory percept in examples of face pareidolia 19 , 21 , 37 and although there have been numerous attempts to determine the source of this variation using models of low-level saliency, curvature and dominant spatial structure 9 , 19 , 37 as well as deep neural networks trained on large image sets 9 , 19 , none of these models have been able to predict face pareidolia illusion, perhaps owning to their high-degree of visual variability among examples of face pareidolia. For example, face pareidolia can occur on the side of a building, in a multi-colored burger being held in two hands or a small, green button.…”

“…At the behavioral level, most studies that have examined our response to the face pareidolia illusion have presented stimuli at fixation and asked participants to report how face-like the image looked 19 – 21 , where the illusory face was looking 22 , or how happy the illusory face appeared to be 23 , 24 . And, although a few studies have measured detection accuracy in the context of visual search 10 , continuous flash suppression 25 , and dot-probe 12 paradigms there have been no attempts to determine whether the face-like advantages conferred by illusory facial features, survive in the periphery.…”

The face pareidolia illusion drives a happy face advantage that is dependent on perceived gender.

“…In Figure 2B ( left ), we have plotted the average “face scores” for the experimental stimuli as a function of their gender and expression conditions. These scores were derived from independent data ( N = 800) shared by Wardle et al (2022) and are thought to describe the strength of the face pareidolia illusion (Taubert et al, 2023; Wardle et al, 2022). When we compared the happy, female stimuli ( M = 7.18, SE = 0.42) to the angry, female stimuli ( M = 6.17, SE = 0.79) using an independent-samples t test (two-tailed), we found no evidence of a difference in illusory strength between the two groups, t (14) = 1.13, p = .28; Figure 2B, left .…”

“…Illusory Strength (Stimulus Ambiguity) Wardle et al (2022) and others (Taubert et al, 2023;Wardle et al, 2020) have demonstrated that ambient examples of face pareidolia vary greatly in their illusory strength. Could the results in Figure 1 reflect the fidelity of the illusory face or the illusory expression?…”