Assigned 112 male Sherman naive albino rats to 12 experimental and 2 no-shock groups. Ss were presented with a receptive female, a nonreceptive female, or a male rat in a whole or 1/2 of a circular chamber. Copulatory and aggressive responses (fighting and attack) were elicited by electric shock applied to the tail. The probability of obtaining either response could be experimentally shifted by manipulating cage size, shock frequency, and sex of the stimulus animal. (PsycINFO Database Record (c) 2006 APA, all rights reserved)