Eye dominance in the small-eared bushbaby, Otolemur garnettii

Abstract

Eye-preference has been measured in the small-eared bushbaby, Otolemur garnettii, using two testing conditions, one requiring the subject to look through a grid and the other involving trained looking through a small hole. Monocular eye use was scored for viewing a variety of stimuli. The six subjects (four adult females and two babies) tested using the grid showed left-eye dominance for viewing the tester. Five subjects were tested for viewing food and all were similarly left-eye preferent. That is, there was indication of an eye preference at the group level. The eye preference did not correlate with handedness for food reaching or holding in the same individuals. When three of the subjects were tested viewing the more arousing stimulus of their babies held in the tester's hand, the eye-preference changed; there was either no preference or a weaker left-eye preference. One subject was tested with novel stimuli (a toy monkey, the tester wearing a mask and a rubber snake) and showed a significant shift to a right-eye preference for viewing two of these stimuli. Increased arousal, or fear, was apparent in the latter tests. Comparison is made to eye dominance data for humans.