Basic-level category processing advantage in fear generalization and its modulation by threat-conditioned stimulus...

Category-based fear generalization refers to the extension of acquired fear responses to novel stimuli sharing categorical cues with a threat stimulus. Categories are organized into superordinate, basic-level, and subordinate levels, which differ in cognitive processing advantages; however, whether this categorical advantage influences fear generalization remains unclear. Experiment 1 used a discriminative fear conditioning paradigm, employing subordinate exemplars of birds and measuring tools as the threat-conditioned stimulus (CS+) and the safety-conditioned stimulus (CS-), respectively. During the generalization test, we included generalization stimuli sharing either the same basic-level category (GS_Basic) or the same superordinate category (but different basic-level category) as the CS+. Fear generalization was assessed via shock expectancy ratings and skin conductance responses. Experiment 2 manipulated CS+ diversity (high vs. low) in the same task while recording electroencephalography to examine its moderating role. Behaviorally, acquired fear generalized more robustly to GS_Basic than to GS sharing the same superordinate category (GS_{Superordinate}). Participants in the high-diversity group showed higher shock expectancy ratings for both the CS+ and GS_Basic than those in the low-diversity group. Event-related potential results revealed that GS_Basic elicited P2 and N400 amplitudes comparable to those of the CS+, and exhibited more positive P2 and less negative N400 amplitudes than GS_{Superordinate} and CS-. Moreover, only the CS+ and GS_Basic elicited more positive LPP amplitudes than CS-. These findings suggest that early attentional allocation, late semantic processing, and motivational attention collectively constitute the electrophysiological basis of the basic-level category processing advantage in fear generalization, offering implications for the intervention of anxiety disorders.