Theory of Mind in adults with right hemisphere damage: What's the story?

Why do people with right hemisphere damage (RHD) have difficulty with pragmatics and communication? One hypothesis has been that pragmatic impairment in RHD is the result of an underlying impairment in Theory of Mind (ToM): the ability to infer the mental states of others. In previous studies evaluating ToM abilities in people with RHD, researchers have used judgment tasks based on story or still cartoon stimuli. However, ToM is likely to draw on kinetic information as well, and these tasks ignore this aspect. The aim of this study was to assess ToM abilities in people with RHD using participants' evaluations of animated films with moving geometric shapes. Participants were presented with eight films of animated triangles. Four of the films represented the triangles as intentional agents with mental states, while the other four represented the triangles as simply inanimate, though moving, objects. Films were evaluated by both button-press response and by oral descriptions. Analysis of the transcriptions revealed that participants with RHD had a reduced ability to discriminate between the film categories, and a bias toward reduced mental-state ascription in the ToM condition.