Dual-Task Costs and the Role of Inhibitory Control in Non- Inferential Theory of Mind Processing

Current methods of assessing an individual’s Theory of Mind (TOM) abilities, especially the false-belief task, assess more than just TOM abilities (Bloom & German, 2000). One such ability in particular, inhibitory control (IC), is believed to be necessary for inhibiting salient and contradictory information about the reality of a situation in order to ascribe a false-belief to an individual (Carlson, Moses, & Breton, 2002; Leslie & Thaiss, 1992). The role of IC cannot be determined precisely, however, as existing tasks confound pure TOM reasoning with other processes (Apperly, Samson, & Humphreys, 2005). The current study sought to assess the role, if any, that IC plays in TOM processing aside from its possible role in making inferences about others’ behavior. The non-inferential TOM task was employed (as used in Apperly, Back, Samson, & France, 2007) to more selectively assess TOM reasoning and a dual-task methodology was used to assess the role of IC. The dependent measure was processing costs, a score comprised of the participant’s accuracy and reaction time. The participants completed the non-inferential TOM task concurrently with a secondary task either in non-inhibitory or inhibitory conditions. Unexpectedly, it was found that participants in the inhibitory conditions performed just as well on the non-inferential TOM task as participants in the non-inhibitory condition. This finding suggests that IC may not be involved in the representation of mental state information. Thus, the findings also suggest that the reason studies show IC to be correlated with other TOM tasks, such as the false-belief task, is because IC is related to the other processes involved in these tasks, such as making TOM inferences. Alternatively, the IC task used may not have been effective and could be the cause of the lack of a main effect for the inhibitory (experimental) condition. Keywords: theory of mind, TOM, non-inferential, inhibitory control.