Preprint: Observational learning of disgust responses

By drawing on the prior experiences of others rather than learning through one’s own experience, individuals can avoid threats associated with direct physical contact. Although observational learning of fear is well established, less is known about whether disgust can be acquired through observational learning and how persistent such socially acquired responses are during direct exposure. We developed a video-based observational disgust-learning paradigm in which 40 healthy participants observed a demonstrator displaying disgust in response to an aversive odor (observed unconditioned stimulus, obs US). The demonstrators’ disgust responses were preceded by a neutral visual cue (conditioned stimulus, CS+), whereas a second cue (CS-) was followed by no response from the demonstrator. Participants subsequently encountered the CS+ and CS- directly. Repeated-measures analyses revealed successful observational disgust learning, indicated by conditioned responses measured as subjective ratings, respiration, and facial expressions. In particular, the CS+ elicited greater unpleasantness, disgust, and expectancy of the US than the CS-. Furthermore, respiratory breath amplitude decreased selectively for the CS+, while facial expressions did not differentiate between the CS+ and CS-. During subsequent direct exposure, CS differentiation in the subjective measures persisted and facial expression analysis revealed greater activation of the upper lip raiser for the CS+ than the CS-. These findings demonstrate that disgust responses can be acquired through observation alone and shape the observer’s responses when encountering cues that previously predicted others’ disgust responses. Our results reveal how social learning contributes to affective and bodily responses of disgust.