The confluence of intrinsic and extrinsic constraints on 3- to 9-month-old infants' catching behavior

The present study sought to uncover what constraints shape the early development of the perceptual-motor skill of catching, and how intrinsic (i.e., movement possibilities) and extrinsic constraints (i.e., object speed imposes temporal precision) impinge on the perception of whether or not a moving object affords catching. Thirty-five infants (with different preferred catching tendencies) between 3 and 9 months of age were presented with balls approaching from the side with different speeds. Video recordings were used to determine how each infant reached for the ball (with the right hand, the left hand or with both hands) and whether these catching attempts were successful (resulting in ball-hand contact). The lower the proportion of failing catching attempts the more accurate the infant perceived the ball's catchability. This accuracy is also reflected in the discrepancy between boundary and success speed (i.e., the difference between the ball speed that still was perceived as catchable and the highest ball speed that was actually successfully managed). The findings indicate that the interaction between infants' intrinsic constraints (which gave rise to, e.g., the preference for two-handed catching and inclination to reach) and the extrinsic constraints (imposed by object speed) induces age-related differences in catching performance and age-related differences in the perception of what action a moving object affords.