From early sensory specialization to later perceptual generalization: dynamic temporal progression in perceiving individual threats.

Threat evokes a variety of negative emotions such as fear, anger, and disgust. Whereas they elicit distinct and even opposite facial, sensory, and autonomic reflexes, threat-related emotions often converge in the actions they prompt (e.g., negative evaluation and avoidance). Here, we tested a unifying hypothesis that threat processing initially involves specialized encoding of individual subtypes to support discrete reflexive operations that later gives way to generalized elaborate analysis to facilitate convergent defensive behavior. Combining event-related potentials (ERPs) and a defensive context in human subjects, we compared temporal courses of perceptual analysis of two threat subtypes-fear and disgust. Indeed, fear enhanced and disgust suppressed early (115 ms) response in visual cortex, accentuating specialized sensory encoding of threat subtypes in accordance with the opposite behavioral and autonomic reflexes they typically elicit. By contrast, later ERP waveforms evoked by fear and disgust merged gradually over time (130-425 ms). Consistently, visual ERPs to anthropomorphic Greeble objects presented after fear versus disgust images also overlapped despite their clear departure from the neutral condition, paralleled by comparable exaggeration in Greeble imminence perception in the two threat (vs neutral) conditions. This later confluence of neural and behavioral response between fear and disgust thus highlights general threat categorization in high-level, downstream perception of threat. By delineating the temporal dynamics in perceiving individual threat emotions, our findings thus provide some of the first evidence to reconcile multidimensional and unidimensional aspects of information processing within the domain of threat, shedding new light on symptom heterogeneity across the anxiety disorder spectrum.