Effects of some volatile sedative-hypnotics on punished behavior.

Lever-press responses of rats were established under a schedule in which punished and unpunished responding alternated. Every 30th response produced food (unpunished responding) during an alternate schedule component, while every tenth response produced both food and shock (punished responding) during an alternate schedule component. Each schedule component was correlated with a different visual stimulus. Unpunished behavior was characterized by high sustained rates which followed brief pauses after food delivery. Punished behavior occurred at less than 10% the rate of unpunished behavior. Oral administration of diazepam, ethchlorvynol, chloral hydrate, tertiary-butanol, and ethanol all produced marked dose-related increases in punished behavior at doses that decreased or had little effect on unpunished responding. Potency estimates for increasing punished responding varied over a 400-fold range. The potency ranking was diazepam greater than ethchlorvynol greater than chloral hydrate greater than tertiary-butanol greater than ethanol. Higher doses of all drugs decreased unpunished responding with relative potencies comparable to those found for doses producing maximal increases in punished responding. Increases in punished behavior appear to be a characteristic feature of drugs with sedative-hypnotic properties.