GROOMING IN THE NORWAY RAT - DISPLACEMENT ACTIVITY OR BOUNDARY-SHIFT

The self-grooming behavior of 11 domestic male Norway rats (Rattus norvegicus) was observed in silence (control condition) and when recorded rat screams were introduced. Upon exposure to the auditory stimulus, significant increases over control levels were observed in the total grooming time, number of grooming bouts, percentage of the total grooming time attributable to face washing, and the number of sample periods in which grooming occurred. Nonsignificant increases were evident for the average bout duration and the absolute time spent face washing. Twenty subjects were then soiled unilaterally with 30 ml of a 2% aqueous agar solution; 10 of these were observed in silence (undisturbed) and 10 in the presence of rat screams (disturbed). Undisturbed subjects groomed the soiled body side significantly more than the intact (clean) side. Disturbed subjects, however, showed no such clear preference in laterality. It is concluded that exposure to auditory stimuli resulted in alterations of grooming behavior. Furthermore, while local pelage factors served to orient grooming in the undisturbed subjects, such factors played a lesser role among disturbed subjects. Although these results are superficially suggestive of a displacement activity, they are more adequately considered within the framework of a more dynamic view of motivational control. © 1979 Academic Press, Inc.