Vigilance performance and extraversion reconsidered: some performance differences can indeed be induced

Many vigilance studies have failed to confirm the hypothesized extraversion-introversion performance differences. Even when putting the conclusions of Koelegaʹs (1992) meta-analysis into practice, performance differences were not found (Brocke, Tasche, & Beauducel, 1997). For the present study, several studies were screened in order to select a vigilance task inducing significant performance differences between extraverts and introverts, and particularly an interaction between extraversion and time-on-task. We chose Carrʹs (1969) auditory paradigm consisting of a 10-min pre- and posttest, and a 40-min central testing block. Thirty-eight extremely extraverted and 36 extremely introverted students were examined using a slightly modified version of Carrʹs paradigm. Participants had to react to the shorter one of two 1 kHz -tones presented binaurally with an event rate of 200 per 10 min. The hypothesized performance differences between extraverts and introverts emerged for mean reaction time (RT) in the 40-min block. Moreover, significant Block × Extraversion × Gender interactions occurred for mean RT and normalized hits. Thus, performance differences could be induced with the auditory paradigm used. Although RT has been neglected as performance parameter in many previous studies, a significant vigilance decrement was found for RT, indicating that RT may be a sensitive performance parameter in monotonous vigilance tasks. The present results are discussed with regard to Eysenckʹs arousal-activation theory and with regard to an extended cognitive-energetic framework.