The Development of Visually Guided Grasping

Prehension, the act of reaching to grasp an object, is vital to the human experience. The Dual Visuomotor Channel Theory (DVCT) proposes that prehension consists of two movements, a reach and a grasp, subserved by distinct, but interacting neural pathways. Developmental evidence in support of the DVCT is lacking, but recent research suggests that initially both the reach and the grasp are guided by tactile inputs and then gradually transition to visual guidance around 1 year of age. If the DVCT is correct, then maturation of the visual control of the reach and the grasp might be expected to follow different developmental timelines. To test this hypothesis 11-14 month old infants were filmed as they reached, grasped, and then ate individual Cheerios placed on a table in front of them. Sighted and blindfolded adults were used for comparison. Frame-by-frame video analysis will be used to determine the extent to which visual versus nonvisual cues are used to direct the reach to the location of the Cheerio versus shape and close the hand to grasp the Cheerio. Hopefully, results will indicate that visual guidance of the reach matures before visual guidance of the grasp. A better understanding of how vision and touch contribute to reach and grasp control could contribute to the development of novel arm and hand prosthetics and robotic machinery and also be used for earlier identification and treatment of patients with developmental sensorimotor disorders