Development of Eye-Hand Coordination in Infant Reaching

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DESCRIPTION (provided by applicant): The steps marking the emergence and development of infant reaching in the first year of life have often been thought to result from changes in the visual-motor processes underlying the planning and execution of movements. For instance, previous accounts proposed that, at the early stages, infants relied on vision to control and guide their hand to the intended goal. Then, as visual guidance of the hand declined, infants used vision increasingly to identify object characteristics and predict the configuration and trajectory of their hand before contact. Recent discoveries, however, have questioned these interpretations. Studies have found that, at the early stages, infants can reach in the dark, suggesting that they do not need to see their hand to guide it to the target. And, other studies have found that at the later stages, infants regress to non-object-related reaching configurations as if they stopped attending to object physical characteristics and lost previous predictive reaching skills. In the light of these recent findings, it has become unclear how visual motor processes contribute to the emergence and development of reaching in the first year. Because previous research has omitted providing direct measures of infant eye movements during reaching it is difficult to understand exactly how vision contributes to movement planning and execution in infancy. The present proposal aims to perform direct measures of infant visual patterns before, during, and after the act of reaching in the 1st year in order to determine whether, when, and how vision is used in the formation and development of reaching. Specifically, experiments will simultaneously acquire precise patterns of eye movements and arm kinematics in one group of infants followed longitudinally over the 1st year and in one group of adult controls. Recordings will be obtained while infants and adults are reaching for objects varying in size and orientation, and while they are simply looking at these objects without reaching. Eye-scanning patterns and point of regard will be compared across age, groups, and object conditions, and will be mapped onto patterns of reaching. These data will allow to determine what information is attended to before and during reaching, and also when not planning to reach. From these data, hypotheses regarding the processes underlying the development of infants' eye-hand coordination in the 1st year will be assessed.