Fear and loathing in the laboratory: An experimental comparison of pavlovian fear and disgust learning.

Research suggests that disgust may be more resistant to extinction than fear, with implications for anxiety disorder treatment. Theory suggests that disgust and fear are driven by distinct cognitive learning mechanisms, yet limited research has directly compared them experimentally as most prior work has examined either fear or disgust in isolation, often using different types of unconditioned stimuli (US). In the present online investigation (collected spring 2025), n = 332 participants (i.e., majority White and female undergraduates) were randomly assigned to one of four differential conditioning paradigms, each defined by the emotion and sensory modality of the US: (a) disgust-auditory (DA), (b) fear-auditory (FA), (c) disgust-images, or (d) fear-images. Participants rated the conditioned stimuli (CSs) using a standard US expectancy scale to assess expectancy learning and using discrete emotion ratings (fear and disgust) and valence ratings (pleasantness) to assess evaluative learning. During acquisition, the DA condition showed the strongest learning when measured via discrete emotion ratings, while the FA condition showed the strongest and fastest expectancy learning. DA was also the most resistant to extinction across both evaluative measures. No group differences emerged for reinstatement based on evaluative indices; however, FA produced the strongest reinstatement in US expectancy, while DA showed the weakest. Overall, results support the idea of differences in learning mechanism, suggesting that disgust learning is driven primarily by evaluative cognition, whereas fear learning is driven by expectancy cognition. Disgust's relative resistance to extinction may be a mechanism explaining poorer treatment outcomes for disorders characterized by heightened disgust. (PsycInfo Database Record (c) 2025 APA, all rights reserved).