P300 as an index of implicit self-esteem.

Abstract

OBJECTIVE: To explore the neural substrates of implicit self-esteem in university students. METHODS: The subjects comprised four females and six males (aged 20-25 years). They were asked to finish the implicit association test (IAT) for implicit self-esteem while brain electrical activity was recorded at 64 scalp sites using tin electrodes mounted in an elastic cap. Mean amplitudes were analysed using a three-way repeated-measure analyses of variance (ANOVA). The ANOVA factors were anterior-posterior electrode location (F, FC, C, CP, P), left-right electrode location (left, middle, right) and task type (self items in the congruent and the incongruent conditions). RESULTS: Robust behavioral data indicated that the participants responded relatively rapidly in the congruent condition when associating self with positive items, supporting the hypothesis that most people have a positive attitude towards self. Scalp event-related brain potential analysis revealed that self items in the congruent condition elicited a more positive ERP deflection than those in the incongruent condition between 350 and 450 ms after the onset of the self items (P300). DISCUSSION: P300 has been shown to be an index of attention to self-relevant stimuli.