Pareidolia is the overinterpretation of stimuli in the external world to impose patterns where none exist. This can apply to any sensory modality but is most commonly applied to visual stimuli. Within this realm, the term is often used to refer to the common human tendency to see faces where no faces are present. Familiar instances would include faces in the clouds, images of saviors in burnt toast, and the Man in the Moon (Liu et al. 2014).
Faces are perhaps the most socially significant visual stimuli encountered in the human environment (Palermo and Rhodes 2007). Autism spectrum disorder (ASD) is characterized by deficits in response to social stimuli (APA 2013). Thus, it has been hypothesized that those with ASD may be less susceptible to this illusion should neurotypical humans. Furthermore, it has been suggested that this feature may be used as a diagnostic tool to identify ASD at a relatively early developmental stage. Both of these hypotheses have received some empirical support.
In respect of the latter, it has been found that children with ASD are less sensitive to pareidolic faces – that is, to objects that most people spontaneously report as possessing a face (Ryan et al. 2016).