The Role of Binocular Vision in Visuomotor Control during Discrete Pointing and Reciprocal Tapping

Abstract

Visual information is integral for executing movements in most daily activities. The accuracy and precision of upper limb movements towards targets are highly dependent on movement planning and the online monitoring of visual feedback. Investigating the effects of amblyopia and strabismus could provide insight into the neuroplasticity of visuomotor control. This study had two objectives: (1) to assess the role of binocular vision in two types of tasks, and (2) to investigate the impact of amblyopia and strabismus on visuomotor control. Two groups of participants were recruited: visually normal adults (n = 40) and patients with amblyopia and strabismus (n = 8). Participants were asked to perform two visuomotor tasks: discrete pointing and reciprocal tapping. For the discrete pointing task, participants pointed to a visual target at either 5º or 10⁰ along the horizontal meridian. For the reciprocal tapping task, participants repeatedly tapped between two targets of various sizes as fast and accurately as possible. For visually normal adults, binocular viewing resulted in faster movements compared to viewing with one eye, demonstrating a binocular advantage for motor efficiency for both discrete and reciprocal tasks. Patients with amblyopia and strabismus executed slower, more cautious movements when viewing with their amblyopic (non-dominant) eye compared to binocular and fellow (dominant) eye viewing. The patients also had significantly better movement performance when using binocular viewing compared to fellow eye viewing for the discrete task, suggesting there was some binocular advantage. The patient group tended to execute their movements faster but was less precise than the control group, suggesting a speed–accuracy trade-off. It is important to acknowledge that the current patient cohort was small and the results should be considered with caution. Nonetheless, the findings demonstrate that binocular vision plays an important role in facilitating the accuracy and precision of upper limb goal-directed movements.