Phenobarbitone and the relationship between extraversion and reinforcement in verbal operant conditioning.

The present investigation was designed to study the relationship between phenobarbitone, extraversion and modes of reinforcement in verbal operant conditioning. A factorial design involving three treatments (placebo and two doses, 30 and 100 mg, of phenobarbitone), two levels of extraversion (extraverts and introverts) and two reinforcement conditions ('good' and 'electric shock') with repeated measures on the first factor, was used. Sixty postgraduate female students were individually subjected to Taffel's verbal conditioning procedure. The results support the following conclusions: (1) under the placebo condition, the extraverted subjects condition better with the rewarding reinforcer ('good') while the introverted subjects condition better with the punishing reinforcer ('electric shock'); (2) under the influence of the smaller dose of the drug, as compared with the placebo, the conditioning scores of extraverted subjects increase with the punishing reinforcer but decrease with the rewarding reinforcer, while the conditioning scores of the introverted subjects decrease with the punishing reinforcer, under the influence of the larger dose of the drug, but remain uninfluenced with the rewarding reinforcer.