Visual modulation of pleasure in subjects with physical and social anhedonia.

Anhedonia is a personality trait associated with a decrease in the ability to feel pleasure. We investigated the experience of pleasure in individuals with physical and social anhedonia for positive pictures with varying levels of luminance contrast. Photographs with either a sensory or a social content were modified with a contrast-gradation procedure. Participants had to report the intensity of the pleasure they experienced in response to these pictures. Twenty-six subjects with physical anhedonia, 18 with social anhedonia and 34 control subjects completed the task. In controls, high-contrast pictures elicited an intense feeling of pleasure, whereas low contrast pictures elicited little pleasure. Although they were also sensitive to the modulation of contrast, subjects with physical and social anhedonia reported less pleasure than controls, across a larger range of contrast levels for sensory and social pictures, respectively. The findings suggest that the deficit in the experience of positive emotion in anhedonia is associated with a diminished pleasure intensity, fairly selective for the sensory or the social emotion dimension. This study encourages further investigation of the interaction between perceptual encoding and emotional processing in anhedonia.