Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Doctor of Philosophy

Program

Psychology

Supervisor

Morton, J. Bruce

Abstract

This dissertation examines the relationship between Theory of Mind (ToM) and Executive Function (EF). There has been debate on whether ToM and EF are two facets of the same process or are two distinct processes. Distinguishing between these possibilities empirically is challenging because the two abilities have similar developmental timetables and ToM tasks typically place high demands on EF, with the consequence that ToM and EF performance measures may be artificially correlated. Three experiments explored the nature of this relationship. Experiments 1 and 2 tested whether socio-cultural factors known to influence individual differences in EF (i.e., bilingualism, country-of-origin) extend to differences in ToM. If ToM and EF are two facets of the same process, then the pattern of differences in EF related to the socio-cultural factors and the pattern of differences in ToM should be comparable. Findings suggest that country-of-origin (but not language status) contributed to differences in EF (Experiment 1). In contrast, neither country-of-origin nor language status was associated with ToM (Experiment 2). Experiment 3 examined whether aging adults’ performance in ToM tasks improves when EF demands are reduced. The results demonstrated that older adults showed intact ToM despite their deficits in EF when reducing cognitive load in a ToM task, implying that correlations between ToM and EF performance may be artificially elevated. Implications of these findings for understanding the relationship between ToM and EF, and suggestions for future studies, are discussed.

Summary for Lay Audience

This dissertation examines the relationship between Theory of Mind (ToM: the ability to understand others’ mind) and Executive Function (EF; a set of cognitive processes necessary for attaining a goal, including the abilities to control one’s attention, plan a strategy, and remember an instruction). It is unclear whether these two abilities stem from one process or are distinct processes. Progress on these issues is slow in part because EF and ToM develop on similar timelines and are measured using similar tasks. Three experiments addressed these issues. Experiments 1 and 2 tested whether individual differences in children’s EF related to socio-cultural factors (i.e., bilingualism and country-of-origin) extend to differences in ToM. Experiment 3 tested whether aging adults’ performance in a ToM task changed when EF demands of the task were reduced. Results from all three experiments suggest that EF and ToM are distinct processes. Experiments 1 and 2 found that Korean children, regardless of their language status, outperformed Caucasian counterparts on an EF task, but were indistinguishable from Caucasian children on a ToM task. Experiment 3 found that older adults’ performance in ToM improved when EF demands in the ToM measure were reduced. The results shed new light on a long-standing debate in Psychology.

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