A different story on "Theory of Mind" deficit in adults with right hemisphere brain damage

BACKGROUND: Difficulties in social cognition and interaction can characterise adults with unilateral right hemisphere brain damage (RHD). Some pertinent evidence involves their apparently poor reasoning from a "Theory of Mind" perspective, which requires a capacity to attribute thoughts, beliefs, and intentions in order to understand other people's behaviour. Theory of Mind is typically assessed with tasks that induce conflicting mental representations. Prior research with a commonly used text task reported that adults with RHD were less accurate in drawing causal inferences about mental states than at making non-mental-state causal inferences from control texts. However, the Theory of Mind and control texts differed in the number and nature of competing discourse entity representations. This stimulus discrepancy, together with the explicit measure of causal inferencing, likely put the adults with RHD at a disadvantage on the Theory of Mind texts. AIMS: This study revisited the question of Theory of Mind deficit in adults with RHD. The aforementioned Theory of Mind texts were used but new control texts were written to address stimulus discrepancies, and causal inferencing was assessed relatively implicitly. Adults with RHD were hypothesised not to display a Theory of Mind deficit under these conditions. METHODS #ENTITYSTARTX00026; PROCEDURES: The participants were 22 adults with unilateral RHD from cerebrovascular accident, and 38 adults without brain damage. Participants listened to spoken texts that targeted either mental-state or non-mental-state causal inferences. Each text was followed by spoken True/False probe sentences, to gauge target inference comprehension. Both accuracy and RT data were recorded. Data were analysed with mixed, two-way Analyses of Variance (Group by Text Type). OUTCOMES #ENTITYSTARTX00026; RESULTS: There was a main effect of Text Type in both accuracy and RT analyses, with a performance advantage for the Theory of Mind/mental-state inference stimuli. The control group was faster at responding, and primed more for the target inferences, than the RHD group. The overall advantage for Theory of Mind texts was traceable to one highly conventional inference: someone tells a white lie to be polite. Particularly poor performance in mental-state causal inferencing was not related to neglect or lesion site for the group with RHD. CONCLUSIONS: With appropriate stimulus controls and a relatively implicit measure of causal inferencing, this study found no "Theory of Mind" deficit for adults with RHD. The utility of the "Theory of Mind" construct is questioned. A better understanding of the social communication difficulties of adults with RHD will enhance clinical management in the future.