Prehension was temporarily handicapped in 57 normal infants by enclosing one hand and forearm in a soft sock. In contrast to control performance infants frequently did not attempt to reach and grasp with the hand thus covered though use of the other arm continued. The disuse exceeded that attributable to the mechanical restriction of the sock.

In younger infants (4 to 6 months of age) it appeared to result from ignorance of the option to attempt prehension with the covered hand. In older infants (6 to 12 months of age) some of the disuse of that arm appeared deliberate, was reversible under circumstances of special need, and there was clearer awareness of the prehensile nature of the arm despite its functional and anatomical distortion by the sock. However, in older infants the unhampered arm and hand were more apt to substitute for the other, and in a few cases disuse and disregard of the arm with the enclosed hand was so extreme as to suggest an agnosia for the arm. The results, which link prehensile disuse to immature concepts of arm function, are relevant to pediatric conditions in which excessive arm disuse may occur, including sensory deprivation, hemiplegic cerebral palsy, brachial plexus palsy, and congenital arm amputations fitted with a prosthesis.

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