[Influence of personality traits on reaction performance in volunteers after a single administration of placebo, crotylbarbital and caffeine].

We examined the influence of single applications of placebo, caffeine (7 mg/kg), and crotylbarbital (2 mg/kg) on reaction and attention performance in 15 volunteers. A newly developed reaction-time apparatus permits the reaction time to be split for differentiation between initiation time and movement time. Moreover, simple and complex attention performance can be quantified. The volunteers were selected as to the dimensions of "introversion/extraversion" and "emotional lability/stability" by means of the Freiburg Personality Inventory. Labile volunteers responded to placebo faster than stables. Caffeine improved mainly the performance of introverted subjects. Crotylbarbital was without influence on the reaction time at the threshold dose applied.