Presentation Title

The Developmental Onset of Visually-Guided Prehension: It’s at the Tip of Your Finger

Format of Presentation

15-minute lecture to be presented April 1, 2017

Location

IB 1015

Start Date

1-4-2017 10:30 AM

End Date

1-4-2017 10:45 AM

Abstract

Multiple Motor Channel (MMC) theory posits that reach movements, which direct the hand to a target’s location, and grasp movements, which open and close the hand to match a target’s shape, are mediated by different neural circuits in sensorimotor cortex. MMC theory predicts that during development, human infants must learn to use vision to coordinate these pre-existing reach and grasp movements into a single fluid act. Furthermore, that the rate at which visual control develops may differ for the reach versus the grasp. To investigate these hypotheses, we used frame-by-frame video analysis to compare the reach and grasp movements of 9, 12, and 15-month-old infants, to those of sighted and blindfolded adults. Preliminary results showed that the 12-month-old infants resembled blindfolded adults in that they did not scale hand aperture to target size prior to target contact, and they relied on initial contact with the underlying table to stabilize their reach endpoint. Yet, after reach stabilization, infants, like sighted adults, could accurately direct a grasping digit to make contact with the target; only then, did infants shape and close the hand to grasp. These preliminary results support the MMC theory by providing evidence that visual guidance of the reach begins to develop before that of the grasp. The results also contrast with traditional neuromaturational theories of development by suggesting that visual guidance of the distal portion of the reach developmentally precedes that of the proximal portion.

Department

Psychology

Faculty Advisor

Jenni M. Karl

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Apr 1st, 10:30 AM Apr 1st, 10:45 AM

The Developmental Onset of Visually-Guided Prehension: It’s at the Tip of Your Finger

IB 1015

Multiple Motor Channel (MMC) theory posits that reach movements, which direct the hand to a target’s location, and grasp movements, which open and close the hand to match a target’s shape, are mediated by different neural circuits in sensorimotor cortex. MMC theory predicts that during development, human infants must learn to use vision to coordinate these pre-existing reach and grasp movements into a single fluid act. Furthermore, that the rate at which visual control develops may differ for the reach versus the grasp. To investigate these hypotheses, we used frame-by-frame video analysis to compare the reach and grasp movements of 9, 12, and 15-month-old infants, to those of sighted and blindfolded adults. Preliminary results showed that the 12-month-old infants resembled blindfolded adults in that they did not scale hand aperture to target size prior to target contact, and they relied on initial contact with the underlying table to stabilize their reach endpoint. Yet, after reach stabilization, infants, like sighted adults, could accurately direct a grasping digit to make contact with the target; only then, did infants shape and close the hand to grasp. These preliminary results support the MMC theory by providing evidence that visual guidance of the reach begins to develop before that of the grasp. The results also contrast with traditional neuromaturational theories of development by suggesting that visual guidance of the distal portion of the reach developmentally precedes that of the proximal portion.