Infant motor planning and prediction: Reaching for a hidden moving object

• Main Author: Robin, Daniel J
• Language: ENG
• Published: ScholarWorks@UMass Amherst 1996
• Subjects: Developmental psychology|Cognitive therapy
• Online Access: https://scholarworks.umass.edu/dissertations/AAI9709645

The importance of continuous sight of the target in 7.5 month old infants' reaching was explored in a task that addressed the issues of infants' ability to anticipate and to retain information about the properties of a hidden object. Barriers and darkness were used to investigate infants' ability to compensate for the physical and visual obstruction of a target object in a reaching task. Infants' ability to intercept a moving object with a partially obscured trajectory was tested. Thirty 7.5 month old infants were presented with a graspable object that moved in a straight-line path through their reaching space. In some conditions the object was obscured by a barrier or by darkness for one second just prior to moving within reach, and infants' frequency of reaching and success at contacting the object were used to evaluate their performance. Further analyses of the infants' looking behavior and of the path of their reaching hand helped to clarify the reasons underlying their successes and failures. Infants showed some ability to adapt to a loss of visual information about the moving target object's position by sometimes successfully contacting the object in the barrier conditions. However, infants reached less often and with less success when access to, or sight of, the target object was obstructed. The infants' visual tracking, obstacle-avoidance skills, and ability to retain information about a hidden object were examined in conjunction with kinematic data to explain infants' limitations in adapting to obstacles in reaching tasks. These limitations involved difficulty visually tracking the object past a barrier, particularly in the dark conditions, as well as difficulty successfully aiming a reach around a barrier. Infants appeared to ignore the path of their hand on its way toward the target object, resulting in the hand frequently contacting a barrier rather than the target. Infants' successful contacts in the barrier conditions suggest that they do not require constant visual information about target position in order to enact a proficient reach. Further, infants appear to predict the reappearance of the target object and remember the path and speed of the object during its occlusion.