Effects of previous housing conditions on shock-induced aggression.

This study investigated shock-induced aggression as a function of housing rats in single or communal cages for varying periods of time before testing. Rates of fighting were unaffected by housing conditions when rats spent seven or 14 days in either of these settings before testing. Placing rats in these settings for 21 or 28 days before testing, however, did affect rates of fighting. Communal caging of subjects for 28 days before testing was particularly deleterious to shock-induced aggression. How rats are housed outside the experimental chamber is a variable affecting shock-induced aggression and should be considered both in designing future studies and as a topic for future investigation.