Examining disgust learning through category conditioning: Evidence from trial-unique presentations and oculomotor avoidance.

Disgust is a basic emotion that motivates avoidance behaviors to protect organisms from pathogens. Objects of disgust are acquired through classical conditioning mechanisms. Oculomotor avoidance serves as an objective marker of disgust, yet previous studies have relied on repeated presentations to establish disgust conditioning. This study aimed to adapt the category-conditioning paradigm (Dunsmoor et al., Cerebral Cortex, 24, 2859-2872, 2014) for disgust learning by employing trial-unique presentations, offering a novel tool for future research. In our experiment, items of two categories - furniture and vehicles - were paired with either disgusting or neutral scenes. Participants' eye movements were tracked, and self-reported measures were collected. The results demonstrated that the category-conditioning task with trial-unique stimuli effectively induced oculomotor avoidance. Participants exhibited both unconditioned avoidance responses to disgusting scenes and conditioned avoidance responses to category items associated with disgust. Eye-tracking data further revealed that disgust-associated stimuli motivated avoidance beyond their role as mere predictors of an aversive stimulus. Interestingly, participants initially exhibited a tendency to view the disgusting image before engaging in avoidance behavior. In conclusion, this study demonstrates that the adapted category-conditioning paradigm successfully elicits conditioned responses using trial-unique stimuli. We believe that this paradigm will provide a valuable tool for future research on disgust learning.