Image type reveals evolutionarily shaped perceptual and conceptual mechanisms of pareidolia.

Pareidolia-the perception of illusory patterns such as faces or objects in ambiguous stimuli-has been extensively studied, but less is known about how different visual environments shape this phenomenon. This study investigated pareidolia experienced in unmodified natural images (NI) and white noise (WN) images in 81 healthy participants under open-ended instructions. Across both conditions, animals were the most commonly perceived pareidolia, consistent with evolutionary pressures favouring rapid detection of biologically relevant stimuli. Importantly, the semantic categories of pareidolia differed by image type: NI evoked significantly more "Natural World" pareidolia, while WN images primarily elicited "Human-Created" pareidolia. This dissociation suggests that NI stimuli engage bottom-up perceptual organization processes whereas WN images depend more heavily on top-down semantic knowledge and mental imagery. Together, these findings indicate that stimulus type modulates the relative contribution of perceptual and conceptual processes in the resolution of visual ambiguity. Beyond their methodological implications for pareidolia research, these results carry broader relevance for understanding creative perception, hallucinations, and cognitive biases that may have been shaped by evolutionary pressures. They also underscore the need for careful and deliberate selection of visual stimuli when employing open-ended tasks in future studies.