Reaching to the Self: The Development of Infants' Ability to Localize Targets on the Body.

This study focused on the development of infants' sensorimotor knowledge about the layout of their bodies. Little is known about the development of the body as a reaching space, despite the importance of this skill for many self-directed adaptive behaviors, such as removing foreign stimuli from the skin or scratching an itch. A new method was developed in which vibrating targets were placed on the heads and arms of 7- to 21-month-old infants (N = 78) to test reaching localization of targets. Manual localization improved with age, and visual localization was associated with successful reaching. Use of the ipsilateral or contralateral hand varied with body region: Infants primarily used the ipsilateral hand for head targets but the contralateral hand for arm targets, for which ipsilateral reaches were not biomechanically possible. The results of this research highlight a previously understudied form of self-knowledge involving a functional capacity to reach to tactile targets on the body surface.