Perceptual-motor coupling in the development of grasp.

OBJECTIVE The purpose of this study was to investigate the effect of haptic attributes of objects on infants' grasping patterns and evaluate whether this effect is influenced by the infant's age (i.e., phase of motor development). METHOD Grasping patterns of 180 infants who were typically developing were measured by the Posture and Fine Motor Assessment of Infants (PFMAI); the PFMAI-I was administered to infants 2 months to 6 months of age (n = 60), and the PFMAI-II was administered to infants 6 months to 12 months of age (n = 120). Grasping patterns were compared for ages by month and for three objects, each with differing haptic features. The interaction between age and object was analyzed. RESULTS Grasping patterns were significantly different when scores by age in months were compared. In addition, grasping patterns differed depending on the object and its haptic features and were influenced by the interaction between object held and age. Certain haptic features were associated with primitive grasp at younger ages and precision grasp at older ages. More mature skills were observed when the objects' haptic features appeared to match an infant's perceptual-motor skill. CONCLUSION The haptic features of objects influence an infant's grasping patterns, and this influence changes with the infant's age. These results suggest that therapists attempt to match the haptic features of objects to the infant's perceptual-motor skill in intervention in order to enhance grasping patterns.