From fascination to fear and disgust: cross-cultural assessment of emotional and aesthetic responses to snake imagery.

The primate visual system is thought to have evolved under selective pressures favouring rapid detection of snakes, ancestral predators that shaped perceptual and attentional mechanisms. Yet, the transition from visual detection to subjective fear remains poorly understood and may depend on specific morphological cues. Here, we examined how snake morphology modulates human emotional and aesthetic responses across ecological and cultural contexts. A total of 377 participants from Portugal (low snake biodiversity) and Brazil (high snake biodiversity) rated images of 92 snake species on fear, disgust, beauty, valence, arousal and perceived size. Cluster analyses revealed three consistent emotional profiles across populations: a High-Fear cluster (mainly viperids, boids and mimics with threatening traits), a High-Valence cluster (mostly harmless colubrids and dipsadids), and a smaller High-Disgust cluster (fossorial or limbless reptiles). Cluster membership was unaffected by country, indicating cross-cultural consistency in emotional evaluations of snake morphology. Species in the High-Fear cluster exhibited higher edge density. By contrast, greater exposure to snakes, particularly in natural environments, was associated with lower Snake Fear Questionnaire scores. These results support the view that humans rely on evolutionarily conserved morphological heuristics (e.g. triangular heads, keeled scales and disruptive patterns) to assess potential threats, while individual predispositions and experience modulate response intensity.