Distinguishing ‘Self’ and ‘Other’ in Theory of Mind Using Behavioural and EEG Measures

This research examined the extent to which ‘Self’ and ‘Other’ belief-attribution processes could be differentiated in the Theory of Mind mechanism, using behavioural and electroencephalography (EEG) measures. A computerized false-belief task was utilized, in which participants were asked to attribute beliefs to either themselves or other people, in a within-subjects, matched design, allowing direct comparison between ‘Self’ and ‘Other’ conditions. Participants were twenty-eight healthy adults (M: 22 years). Behavioural data revealed that participants responded significantly faster to self-oriented questions (M = 833ms) than other-oriented questions (M = 925ms). Of particular interest, an effect of ‘perspective-shifting’ was found: when asked to shift from the self-perspective to the other-perspective within a trial, participants response times were significantly slower (M = 979ms) than when shifting from the other-perspective to the self-perspective within a trial (M = 821ms). It is suggested that the ‘self’ forms the stem of understanding the other, with the ‘other’ only processed when explicitly necessary, whilst the ‘self’ is processed regardless of ultimate task demands (i.e. to orientate to ‘self’ or ‘other’ perspective). EEG measures were also taken during completion of the Theory of Mind task, to assess neural correlates of the Self/Other differentiation. Results demonstrated a significant difference in brain activity between ‘Self’ and ‘Other’, maximal over central parietal lobes, from 550ms after onset of probe stimulus (i.e. when question was presented to prime either a self-oriented or other-oriented response). The behavioural and EEG outcomes support the notion of a differentiation between ‘Self’ and ‘Other’ in the Theory of Mind mechanism, further demonstrating a distinction between necessary abilities for attribution of beliefs to oneself versus other people, as opposed to a general ‘belief-attribution’ capacity used for both self and other oriented processing.