25 male guinea pigs, reared from 2 days of age, were randomly assigned to the following conditions of social environment and physical restraint: isolated confined, isolated nonconfined, social confined, and social nonconfined. It was hypothesized that the absence or diminution of sexual activity previously observed to be associated with social isolation might be a function of a confinement-induced increase in frequency of aberrant motor activity. Ss reared in social isolation and/or confinement exhibited a high frequency of aberrant response but no relationship between motor symptoms and sexual adequacy was found. In addition, confinement initiated after maturity resulted in aberrant motor activity but no accompanying decrement in sexual behavior. (PsycINFO Database Record (c) 2016 APA, all rights reserved)