One object with two identities: The rapid detection of face pareidolia in face and food detection tasks

Humans are so sensitive to faces and face-like patterns in the environment that sometimes we mistakenly see a face where none exists – a common illusion called “face pareidolia”. Examples of face pareidolia, “illusory faces”, occur in everyday objects such as trees and food, and contain two identities: an illusory face, and an object. In this study, we studied illusory faces in a Rapid Serial Visual Presentation (RSVP) paradigm over three experiments to explore the detectability of illusory faces under various task conditions and processing speeds. The first experiment revealed the rapid and reliable detection of illusory faces even at an extremely limited processing time of 34 ms, suggesting that face pareidolia arises from an error in rapidly detecting faces. Experiment 2 demonstrated that illusory facial structures within food items did not interfere with the recognition of the object's real identity, affirming that examples of face pareidolia maintain their object identity. Experiment 3 directly compared behavioural responses to illusory faces under different task demands, indicating that when processing time is extended, the object identity dominates perception. From a behavioural context, the findings revealed that illusory faces maintain concurrent identities as both faces and objects. The study sheds light on the brain's processing of objects with dual identities, contributing to our understanding of visual stimulus recognition. Future research could explore the neural representation of these unique stimuli under varying circumstances and attentional demands, providing deeper insights into the perception of face pareidolia.