Western Undergraduate Psychology Journal

Article Title

Hemispheric Lateralization of Theory of Mind


Theory of mind (ToM) is defined as the ability to imagine and reason about states of mind that others hold. This skill is essential for functioning in the social world and core deficits in ToM are seen in the autism spectrum disorder (ASD) population. Recent studies have shown ToM to be functionally lateralized on the right side of the brain, specifically located in the right temporoparietal junction (RTPJ; Saxe & Wexler, 2005). This study examined to what extent ToM is right lateralized, and sought to test the right lateralization account with a behavioural study. A series of 3 experiments were performed, which compared participants’ reaction times to ToM information presented to the left and right visual fields and motor responses with left and right hands. Based on well-established findings of the motor advantages of one’s dominant hand (Annett, 1970), a right hand advantage on the present task was predicted if ToM is bilaterally distributed across the two sides of the brain. However, if ToM is right lateralized, the left hand should receive its own advantage because the right hemisphere controls it, which predicts that the left hand should be as fast as, if not faster, than the right hand. No significant differences between the two presentation sides or responding hands were found, thus providing moderate support for the right lateralization of ToM. The implications of this in terms of the ASD population are discussed, as well as suggestions for future research that will build upon this finding.

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