Under what conditions does laboratory male rat initiate copulatory behaviour with passively receptive female.

Intact, adult male rats with a minimal copulatory experience acquired in interaction with fully proceptive (exhibiting ritualized dartings) female were tested at 1, 24, 48, 96 and 192 hour afterwards by means of passively receptive (responding with lordosis posture only) females. Only five males initiated copulations with lordotic females throughout the whole experiment. Because in the 192 hour test all the males copulated, the development of ability to initiate copulations could not be ascribed to the sexual experience only. Most probably, merely repeated exposition of the males to the passively receptive females resulted in the increase of the hormonal activity. The acquired ability of males to initiate copulations with thus behaviourally weak stimulus females persisted after sixty-four days of heterosexual abstinence. The observed variance in the latencies of the first intromission and in the number of incomplete mounts preceding the first intromission is interpreted in the sense of a parallel action of the processes of learning as well as of hormonal activation.