Abstract
Rats were familiarized to one compartment of a test box and then given access to this and a novel compartment. Females spent more time in the novel compartment than males did and this difference was found to be independent of a possible difference in familiarity with the familiar compartment arising from the females' higher frequency of ambulating and rearing with sniffing during familiarization. This is evidence of a sex difference in response to novelty independent of activity differences. Females also had shorter approach latencies to the novel compartment. These sex differences could reflect differences in either fearfulness or curiosity.