[..]Pareidolia can cause people to interpret random images, or patterns of light and shadow, as faces.[2] A 2009 magnetoencephalography study found that objects perceived as faces evoke an early (165 ms) activation of the fusiform face area at a time and location similar to that evoked by faces, whereas other common objects do not evoke such activation. This activation is similar to a slightly faster time (130 ms) that is seen for images of real faces. The authors suggest that face perception evoked by face-like objects is a relatively early process, and not a late cognitive reinterpretation phenomenon.[3] A functional magnetic resonance imaging (fMRI) study in 2011 similarly showed that repeated presentation of novel visual shapes that were interpreted as meaningful led to decreased fMRI responses for real objects. These results indicate that the interpretation of ambiguous stimuli depends upon processes similar to those elicited by known objects.[4]
These studies help to explain why people identify a few circles and a line as a "face" so quickly and without hesitation. Cognitive processes are activated by the "face-like" object, which alert the observer to both the emotional state and identity of the subject, even before the conscious mind begins to process or even receive the information. The "stick figure face", despite its simplicity, conveys mood information (in this case, disappointment or mild unhappiness). It would be just as simple to draw a stick figure face that would be perceived (by most people) as hostile and aggressive. This robust and subtle capability is hypothesized to be the result of eons of natural selection favoring people most able to quickly identify the mental state, for example, of threatening people, thus providing the individual an opportunity to flee or attack pre-emptively. In other words, processing this information subcortically — therefore subconsciously — before it is passed on to the rest of the brain for detailed processing accelerates judgment and decision making when a fast reaction is needed.[5] This ability, though highly specialized for the processing and recognition of human emotions, also functions to determine the demeanor of wildlife.[6]
Pareidolia can be considered a subcategory of Apophenia[..].