The effects of chlordiazepoxide on a delayed pair comparison task in pigeons

Five pigeons were successfully taught a variation of the Konorski delayed pair comparison task, using a red and a green stimulus. The bird was required to respond to the left or right hand key, depending on whether the 2 successively presented centre key stimuli were the same (left) or different (right). The delay intervals ranged from zero to 9 s, and stable performance decrements (with increasing delay) were obtained. Chlordiazepoxide which, it has been argued, produces behavioural changes similar to those observed after hippocampal lesions was found to disrupt performance at doses greater than 4 mg/kg (i.m.). All delays (including zero) were affected. Some interpretations of this result in terms of encoding and attention are discussed, and some reference made to the possible neuropharmacological basis of this drug action.