Cerebral hemovelocity reveals differential resource allocation strategies for extraverts and introverts during vigilance.

Extraversion--one of the Big 5 personality factors--correlates negatively with vigilance, but most studies focus on performance outcomes and not the performance process. Previous research has shown that transcranial Doppler sonography (TCD), which measures cerebral blood flow velocity (CBFV), can be used to examine resource allocation strategies during vigilance performance. Hence, this study was designed to assess the attentional resource allocation strategies of introverts and extraverts using the CBFV measure. Twelve extroverts and 13 introverts monitored a 60-min vigilance task for a critical signal--the absence of a line on a five-circle array. The results revealed an overall performance decrement that was not modulated by extraversion. We observed an interaction between extraversion and time; CBFV declined in the introversion group, but not in the extraversion group. Additionally, an interaction between cerebral hemisphere and personality revealed that extraverts were recruiting resources from both the left and right cerebral hemispheres, while introverts only recruited resources from the right hemisphere. The results suggest that extraverts can allocate compensatory effort to mask performance differences. We discuss the theoretical and practical implications of these findings and offer future research directions that may help us understand these effects.