THE DEVELOPMENT OF HAPTIC PERCEPTION DURING INFANCY
Emily W. Bushnell J. Paul Boudreau Tufts University
The evolution of the forepaws into prehensile hands adapted to explore, maneuver, and exploit objects is recognized as a critical factor in the phylogeny of humans. Similarly, the development of the skillful use of the hands for these purposes is a significant aspect of human ontogeny. Parents and pediatricians alike chart children's "fine motor development," which encompasses a variety of intricate manual behaviors involved in self-feeding, self- dressing, tool use, and writing. In addition to achieving these well-known performatory milestones during the first years of life, children also gain considerable ability to use their hands as a means for acquiring information about objects and surfaces, for discriminating and identifying them. The early development of this perceptual function of the hands is the focus of this chapter. We will consider how the infant becomes able to use the hands to assess qualities of objects such as shape, texture, hardness, size, temperature, and weight.
Our discussion will not be exhaustive. For one thing, we will not incorporate infants' abilities to perceive object properties orally. Although mouthing is often considered a form of tactual exploration and is surely an important source of information for infants, its developmental course and its functioning with regard to various object properties are quite different from those of manual exploration (see Rochat, 1987; Ruff, 1989). Hence, we think it is appropriate to treat mouthing as essentially a different modality from per-