Dextroamphetamine and individual susceptibility to reinforcement in verbal operant conditioning

The present investigation was designed to study the relationships between extraversion, d-amphetamine and modes of reinforcement in verbal operant conditioning. A factorial design involving two levels of extraversion (extraverts and introverts), two reinforcement conditions ('good' and 'electric shock') and three treatments (placebo and two doses, 7.5 and 12.5 mg, of d-amphetamine) with repeated measures on the last factor was used. Sixty postgraduate female students were individually subjected to Taffel's verbal conditioning procedure. The study supported the following conclusions: (1) under the placebo condition, the extraverted subjects condition better with the rewarding reinforcer while the introverted subjects condition better with the punishing reinforcer; (2) under the influence of d-amphetamine, the extraverted subjects condition better with the punishing reinforcer while the conditioning scores of introverted subjects decrease with the punishing reinforcer but are not influenced with the rewarding reinforcer.