P3 amplitude and time-on-task effects in distractible adolescents.

OBJECTIVE: The aim of our study was to examine the role of brain activity related to stimulus evaluation processes in distractibility by analyzing the P3 event-related potential. METHODS: We studied the P3 response to target stimuli at the beginning, in the middle, and at the end of a two-tone auditory oddball task in easily distractible (n = 16) and non-distractible (n = 16) adolescents. RESULTS: Easily distractible adolescents showed enhanced frontal and reduced parietal P3 amplitude across the blocks relative to non-distractible adolescents. Also, the usual decline in P3 amplitude at the end of the task was significantly larger in distractible than in non-distractible adolescents. CONCLUSIONS: These results suggests that the P3 effects are not limited to the neuropsychiatric disorders, and that increased distractibility may be characterized by reduced amount of resources allocated to the task with continued testing. SIGNIFICANCE: The results of this study contribute to elucidation of the functional basis of distractibility.