Sociability/impulsivity and attenuated dopaminergic arousal: Critical flicker/fusion frequency and procedural learning

Two experiments examined the interaction of sociability (Sec) and impulsivity (Imp) components of extraversion and reduced dopamine activity (by haloperidol) on critical flicker/fusion frequency change scores (Delta CFFT) and procedural learning. In double-blind designs, subjects received either haloperidol (5 mg) or placebo; Soc and Imp were randomly sampled. In Experiment 1, Drug x Imp, and Drug x Imp x Soc interactions were found on Delta CFFT; in Experiment 2, a drug x Soc interaction was found on procedural learning. In both experiments, introverts seemed over-aroused under placebo (putatively due to the medical context), more optimally aroused under haloperidol; for procedural learning, extraverts seemed more optimally aroused under placebo, less optimally aroused under haloperidol. These data indicate that both Soc and Imp mediate the effects of arousal; Drug x Imp effects my conceal joint effects of Soc x Imp; and that Soc shows more consistent effects than Imp. These data complement a previous study of Soc/Imp and caffeine-induced arousal (Corr, Pickering & Gray, 1995), and lend support to H. J. Eysenck's (1967) arousal model of Extraversion. (C) 1997 Elsevier Science Ltd.