Influence of Perceptual and Conceptual Information on Fear Generalization : A Behavioral and Event-Related Potential Study

Abstract

Learned fear can be generalized through both perceptual and conceptual information. This study investigated how perceptual and conceptual similarities influence this generalization process. Twenty-three healthy volunteers completed a fear-generalization test as brain activity was recorded in the form of event-related potentials (ERPs). Participants were exposed to a de novo fear acquisition paradigm with four categories of conditioned stimuli (CS): two conceptual cues (animals and furniture); and two perceptual cues (blue and purple shapes). Animals (C+) and purple shapes (P+) were paired with the unconditioned stimulus (US), whereas furniture (C−) and blue shapes (P−) never were. The generalized stimuli were thus blue animals (C+P+, determined danger), blue furniture (C−P+, perceptual danger), purple animals (C+P−, conceptual danger), and purple furniture (C−P−, determined safe). We found that perceptual cues elicited larger fear responses and shorter reaction times than did conceptual cues during fear acquisition. This suggests that a perceptually related pathway might evoke greater fear than a conceptually based route. During generalization, participants were more afraid of C+ exemplars than of C− exemplars. Furthermore, C+ trials elicited greater N400 amplitudes. Thus, participants appear able to use conceptually based cues to infer the value of the current stimuli. Additionally, compared with C+ exemplars, we found an enhanced late positive potential effect in response to C− exemplars, which seems to reflect a late inhibitory process and might index safety learning. These findings may offer new insights into the pathological mechanism of anxiety disorders.