Effects of alcohol on speaking in isolated humans.

Drugs of abuse often increase human social interaction, as is suggested in our cultural drug use practices and has been demonstrated in controlled laboratory studies. The environmental and pharmacological mechanisms controlling these effects remain unclear. The present study examined the importance of a social context for obtaining drug-produced increases in human speech by examining the acute effects of alcohol (0, 22, 45, 67 g) on the amount of speech emitted by six normal volunteers who were producing speech monologues in an isolated context. A within-subject repeated-measures experimental design was used. Alcohol produced a significant dose-dependent increase in total speech. Conversely, response rates on a nonverbal behavioral task (circular-lights device) decreased as an orderly function of alcohol dose. These results suggest that a social context is not a necessary condition for alcohol to increase rates of human speech. Moreover, the decreases in response rates observed in the nonverbal task rule out the possibility that alcohol affected total speech via a generalized increase in overall activity levels.