PENILE ERECTION - A REFLECTION OF SEXUAL AROUSAL AND AROUSABILITY IN MALE CHIMPANZEES

A study was conducted to determine if sexual motivation in male chimpa nzees, defined by the two components, sexual arousal and arousability, could be quantified by measuring penile erection during laboratory pa ir-tests of sexual behavior. Sexual arousal, the momentary level of se xual excitation, was quantified by single measurements on a scale of p enile erection. Sexual arousability, the propensity for arousal, was q uantified by the rate of approach to full erection and by mean erectio n scores. Sexual arousability, as defined, was related to the frequenc y of male courtship displays, copulations, and ejaculations, which wer e highest at midcycle and positively correlated with a quantitative me asure of female anogenital swelling. Sexual arousal was negatively cor related with continued exposure to the female and least variable durin g midcycle. These operational definitions of sexual motivation in the male chimpanzee facilitate comparative research in which analogous ind exes of sexual motivation are required, such as when extrapolating fro m animal to human. (C) 1997 Elsevier Science Inc.