Aversively conditioned context enhances visual size illusion via stimulus-specific neural networks

Emotion-perception interaction is a fundamental question in cognitive neuroscience, yet the underlying neural mechanisms remain poorly understood. Here, we probed this issue by combining fear conditioning paradigm with the classic Ebbinghaus illusion. We associated the surrounding context of the Ebbinghaus illusion with aversive stimuli (electric shock or intense noise) and measured behavioral and neural responses. Behaviorally, aversively conditioned contexts enhanced the perceived size illusion effect, with shock producing a stronger conditioning effect than noise. Neuroimaging revealed distinct neural pathways mediating these effects: shock conditioning strengthened occipital-to-parietal connectivity, while noise conditioning enhanced prefrontal-to-parietal connectivity. Moreover, noise relative to shock conditioning elicited greater activation in both the lateral amygdala (LA) and dorsolateral prefrontal cortex (dlPFC), and weakened LA-to-dlPFC connectivity. The findings suggest that aversive learning experiences shape human visual perception through stimulus-specific neural networks, advancing our understanding of emotion-perception interaction, and providing crucial insights for clinical interventions targeting fear-related perceptual distortions.