Biased intensity judgements of visceral sensations after learning to fear visceral stimuli: a drift diffusion approach

A growing body of research has identified fear of visceral sensations as a potential mechanism in the development and maintenance of visceral pain disorders. However, the extent to which such learned fear affects visceroception remains unclear. To address this question, we used a differential fear conditioning paradigm with non-painful esophageal balloon distensions of two different intensities as conditioning stimuli (CSs). The experiment comprised pre-acquisition, acquisition and post-acquisition phases during which participants categorized the CSs with respect to their intensity. The CS+ was always followed by a painful electrical stimulus (unconditioned stimulus, US) during the acquisition phase and in 60% of trials during post-acquisition. The second stimulus (CS-) was never associated with pain. Analyses of galvanic skin and startle eyeblink responses as physiological markers of successful conditioning showed increased fear responses to the CS+ compared to the CS-, but only in the group with the low intensity stimulus as CS+. Computational modeling of response times and response accuracies revealed that differential fear learning affected perceptual decision-making about the intensities of visceral sensations such that sensations were more likely to be categorized as more intense. These results suggest that associative learning might indeed contribute to visceral hypersensitivity in functional gastro-intestinal disorders.