Contact with estrus female as a reward for instrumental response in a growing male rat from the 3rd up to the 14th week of life

Abstract

The bar-press response reinforced by the contact with estrus female was investigated in growing male rats. The bar-press latency as well as the subjects' behavior changed distinctly in the course of the study with the increase of experience and maturation of the subjects. Some behavioral items such as, nasogenital contact, climbing on the head, and running around showed gradual increase during succeeding weeks of life, parallelly to the decrease of the sitting under female, and crawling under female. A gradual shortening of the bar-press latencies was observed from the 4th to the 11th week of life succeeded by a prolongation from the 11th to the 14th week. On the basis of the changes in bar-press latencies as well as of the analysis of the subjects' behavior it is suggested that the young male rat between the 4th and 7th week of life comes under an increasing influence of sexual motivation.