Human social conversation: effects of ethanol, secobarbital and chlorpromazine

Effects of oral ethanol, secobarbital and chlorpromazine on human vocalization were studied in a dyadic social situation using repeated observations within subject pairs. Throat microphones and voice operated relays were used to measure quantitative aspects of vocalization (conversational speech) during daily experimental sessions. Ethanol (1-6 oz of 95-proof) and secobarbital (30-300 mg) produced dose-related increases in vocalization by the subject who received active drug, while vocalization by the partner who received placebo only was not generally altered systematically. Chlorpromazine (25-100 mg) produced dose-related decreases in amount of vocalization by the subject and vocalization by partners tended to decrease as well on days when the subject received active drug. Selected scales from the Addiction Research Center Inventory were administered following social sessions to assess subjective drug effects. No consistent changes on ARCI scales were obtained after ethanol or secobarbital, while chlorpromazine produced dose-related increases on the PCAG scale. Overall, quantitative measures of vocalization in a social context provided a reliable and sensitive indicator of dose-related drug effects.