Evaluative differential conditioning of disgust: a sticky form of relational learning that is resistant to extinction.

The present study sought to (a) test whether autonomic (i.e., electrodermal) and evaluative conditioning can be differentially established to verbal CSs, and (b) whether extinction procedures can reliably attenuate differential conditioned evaluative responding. Thirty undergraduates underwent a 10-min adaptation period followed by three consecutive conditioning phases: habituation, acquisition, and extinction. Conditioning involved participants viewing two semi-randomly presented words on a computer monitor. During acquisition, one word (CS+) was reliably paired 12 times with the UCS (pictorial stimuli depicting bodily mutilation), whereas the remaining word (CS-) was presented 12 times and reliably followed by neutral pictures (inanimate common objects). As predicted, electrodermal and evaluative responses during acquisition were of larger magnitude to the CS+ compared to the CS-. During extinction, participants continued to evaluate the CS+ as more disgusting relative to the CS-, whereas distress and fear-related emotional ratings attenuated across extinction trials. The implications of these findings for the modifiability of disgust-based evaluative responses in specific anxiety disorders will be discussed.