Effects of d-amphetamine on choice of social versus monetary reinforcement: a discrete-trial test

Two mutually exclusive options were concurrently available to eight volunteers during 60-min experimental sessions. Subjects chose every three minutes between conversing with another same-sex volunteer and providing speech monologues for monetary reinforcement. d-Amphetamine (12.5 and 25 mg/70 kg) significantly increased choice of social over monetary reinforcement. Drug-produced increases in choice of the social option were associated with increases in total seconds of speech and the rate of social conversation. d-Amphetamine also increased subject ratings of effects indicative of greater sociability such as friendliness, elation and energetic. These results suggest that d-amphetamine can increase the relative reinforcing effects of social interaction.