| Abstract: | In our view open-field testing entails both a predatory encounter, which occurs as a consequence of handling and placement of subjects into the testing apparatus, and sudden social separation from conspecifics. We hypothesize, therefore, that open-field behavior represents a compromise between responses aimed at minimizing detectability as a predator evasion tactic, and those which are motivated by attempts to reinstate contact with companions. Six experiments were conducted using rats and mice to test various implications of this model. Pretest shock and the presence of a human observer each retarded the appearance of social reinstatement behaviors and enhanced responses which minimize detectability in both species. Likewise, because of diminished reinstatement tendencies animals tested in pairs froze longer than those tested individually. The applicability of this model to other aspects of open-field behavior in rodents was examined, and the contrast between this view and the general emotionality hypothesis was briefly discussed. |
