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The development of functional reaching in infants
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THE DEVELOPMENT OF FUNCTIONAL REACHING IN INFANTS Michael E. McCarty, Rachel K. Clifton, & Roberta R. Collard Department of Psychology University of Massachusetts, Amherst Box 37710 Amherst MA 01003-7710 Functional reaching indicates the ability to anticipate the consequences of a motor action and to use the anticipated outcome for planning a motor action. A functional reaching strategy is defined as grasping an object in a manner that places the object in position for its intended use. For example, when reaching for a spoon which has food in the bowl, grasping the spoon's handle with the bowl projecting from the radial side of the hand is functional because the food can be efficiently transported to the In contrast, grasping the bowl of the spoon typically mouth. does not result in getting much food into the mouth, and grasping the spoon's handle with the bowl projecting from the ulnar side of the hand requires additional manipulation of the spoon or an awkward movement to the mouth. The purpose of this study was: 1) to document reaching strategies for infants from 9 to 19 months of age, 2) to determine whether functional strategies increase over this period, and 3) to see if reaching strategies vary with the kind of object presented. Three groups of infants (9, 14, and 19 months) were videotaped while reaching for a spoon and for toys attached to a handle. The objects were placed horizontally on a stand at midline, and were oriented to the left and right on alternate trials. Hand use was recorded for each trial, and a reaching strategy was identified from the pattern of results. A preferred hand strategy involved consistently reaching with the dominant hand: a salience strategy involved reaching with the hand on the same side as the salient end of the object (i.e., the side with the toy or bowl of the spoon); and a functional reaching strategy involved reaching with the hand on the same side as the handle. The Preferred Hand Strategy showed a decrement in the Spoon condition with increasing age, but no trend in the Toy condition. The Salience Strategy showed that few infants used this strategy in the Spoon condition, and use of this strategy decreased with age. The Functional Reaching Strategy was shown to increase with age in both conditions, but the increase was more dramatic in the Spoon condition. In conclusion, infants become increasingly able anticipate the outcome of their motor actions, and begin to plan a sequence of actions for grasping a handle and bringing food to the mouth in an efficient manner. The toys on the handle could be grasped in any of several ways with little consequence for subsequent exploration, and the infants apparently were sensitive to that difference.
THE DEVELOPMENT OF FUNCTIONAL REACHING IN INFANTS Michael E. McCarty, Rachel K. Clifton, & Roberta R. Collard Department of Psychology University of Massachusetts, Amherst Box 37710 Amherst MA 01003-7710 Functional reaching indicates the ability to anticipate the consequences of a motor action and to use the anticipated outcome for planning a motor action. A functional reaching strategy is defined as grasping an object in a manner that places the object in position for its intended use. For example, when reaching for a spoon which has food in the bowl, grasping the spoon's handle with the bowl projecting from the radial side of the hand is functional because the food can be efficiently transported to the In contrast, grasping the bowl of the spoon typically mouth. does not result in getting much food into the mouth, and grasping the spoon's handle with the bowl projecting from the ulnar side of the hand requires additional manipulation of the spoon or an awkward movement to the mouth. The purpose of this study was: 1) to document reaching strategies for infants from 9 to 19 months of age, 2) to determine whether functional strategies increase over this period, and 3) to see if reaching strategies vary with the kind of object presented. Three groups of infants (9, 14, and 19 months) were videotaped while reaching for a spoon and for toys attached to a handle. The objects were placed horizontally on a stand at midline, and were oriented to the left and right on alternate trials. Hand use was recorded for each trial, and a reaching strategy was identified from the pattern of results. A preferred hand strategy involved consistently reaching with the dominant hand: a salience strategy involved reaching with the hand on the same side as the salient end of the object (i.e., the side with the toy or bowl of the spoon); and a functional reaching strategy involved reaching with the hand on the same side as the handle. The Preferred Hand Strategy showed a decrement in the Spoon condition with increasing age, but no trend in the Toy condition. The Salience Strategy showed that few infants used this strategy in the Spoon condition, and use of this strategy decreased with age. The Functional Reaching Strategy was shown to increase with age in both conditions, but the increase was more dramatic in the Spoon condition. In conclusion, infants become increasingly able anticipate the outcome of their motor actions, and begin to plan a sequence of actions for grasping a handle and bringing food to the mouth in an efficient manner. The toys on the handle could be grasped in any of several ways with little consequence for subsequent exploration, and the infants apparently were sensitive to that difference.