Abstract
Purpose: It is known that binocular cues provide important information for prehensile movements of reaching and grasping. Studies have generally explored conditions where binocular cues are present (binocular viewing) compared to when they are absent (monocular viewing). Little is known about how disrupting binocular cues affects prehensile movement behaviour. Method: Binocular cues were disrupted by means of a blurring lens (+6.00DS) placed in front of one eye. Measurements were obtained in a group of 10 young subjects with normal binocular vision. Prehensile movements for transport and grasp components were measured. Results: Kinematics indices were compared for conditions where binocular cues were present to when they were absent, and when disrupted. Repeated measures (ANOVA) revealed a significant effect with maximum velocity (F 2,27=6.93 p=0.005). Post hoc analysis demonstrated that maximum velocity did not change significantly in the absence of binocular cues (p=0.79). However it was significantly lower when binocular cues were disrupted (p=0.027). In addition, the velocity was also significantly lower in the disrupted cue condition compared to monocular (p=0.06). Maximum grip aperture demonstrated a significant effect (F 2,27=20.98 p=0.002) with the different conditions. Post hoc analysis showed that the grip aperture was significantly larger when cues were absent (p=0.02), and when disrupted (p=0.0015) compared to binocular condition. Further, grip apertures in disrupted cue conditions were significantly larger than no-cue condition (p=0.07). Conclusions: Although only the grasp component is affected when binocular cues were removed, both the transport and grasp behaviour change when binocular cues are disrupted. Factors other than stereopsis which may also contribute, are discussed.
Supported by College of Optometrist to SP.