The Role of Binocular Vision during the Performance of Complex Manipulation Skills

Abstract

The overall goal for this thesis was to examine the significance of binocular vision during the performance of complex manipulation tasks in visually-normal children and adults. The goal of study 1 was to examine the age-related contribution of binocular vision to the performance of manipulation skills. Healthy children (n=58, age: 5-13 years) and adults (n=19, age:17-38 years) performed two manipulation tasks: peg-board and bead-threading, under randomized viewing conditions (binocular, right and left-eye monocular). The main outcome measure was movement time to complete the task. Results showed that the contribution of binocular vision differs based on age (i.e., greater in children) and on the task (i.e., greater in the bead-threading task). In study 2, the goal was to examine the significance of binocular vision during the performance of complex manipulation tasks in children with learning difficulties. Thus, the performance of fine motor skills was compared among children with learning difficulties (n=19, age: 5-12 years) and their age-matched peers tested in study 1. Results showed that children with learning difficulties were significantly slower than their peers on the bead-threading task, but performed similarly to their peers on the peg-board task. The aim of study 3 was to characterize the role of binocular vision in the performance of manipulation tasks involving tool use in visually-normal adults. Healthy adults (n=36, age: 17-38 years) performed five manipulation tasks (bead-threading, peg-board with fingers, and with tweezers, precision pointing with a tool, and picking up a target using a hook-tool) during binocular and monocular viewing. Results showed that binocular vision provides critical sensory input when the task involves precise manipulation of small objects, either when using hands directly or when using a tool to pick up the object. This thesis has two main conclusions. First, the importance of binocular vision for the performance of manipulation skills is highly dependent on the task. An important implication of this work is that a binocular visual screening is recommended for persons whose occupation requires manipulation of small object. Second, the ability to perform skilful manipulations improves significantly during development and our results indicate that normal binocular vision plays an important role in this process. Furthermore, the performance of fine motor skills differentiates between children with and without learning difficulties. Based on these results, including an assessment of fine motor skills in children with abnormal binocular vision and children with learning difficulties is highly recommended