Hear it, fear it: Fear generalizes from conditioned pictures to semantically related sounds

Fear generalization is thought to be an important mechanism in the acquisition and maintenance of anxiety disorders. Previous studies have investigated fear generalization within one sensory modality - mainly within the visual domain. However, a growing body of evidence shows that emotional information is processed in more than one sensory modality. Based on network theories, we expected that fear may also generalize from stimuli in one sensory modality to another. To test our hypothesis, 42 participants underwent a differential conditioning paradigm, during which pictures were either presented with (vCS+) or without (vCS-) an aversive electric stimulus. After the acquisition phase, generalization was tested in the crossmodal group (n = 21) by presenting sounds which were semantically congruent to the visual vCS+ (i.e., the aGS+) or the vCS- (i.e., the aGS-). As a control, the unimodal group (n = 21) saw the pictures again. For the crossmodal group, we could show that US expectancy ratings generalized from conditioned pictures (vCS+) to semantically related sounds (aGS+). Moreover, when the vCS+ was presented during extinction, fear of the aGS+ extinguished, whereas extinction training with the aGS+ was found to be less effective for the vCS+. The findings are relevant for crossmodal fear acquisition and exposure therapy.