The Development of Finger Differentiation

Abstract

The ability to perform discriminations based on the classification of sensory input from the fingers in terms of the individual fingers stimulated in their correct spatial arrangement, was tested in a group of normal children aged 4 1/2 to 7 1/2 years. The results showed that the acquisition of this ability depended upon chronological age in a regular fashion, suggestive of maturation of a unitary function (“finger sense”) in a population subject to normal variation. The significance of this finding in the wider context of the acquisition of abilities during normal development is discussed. The ability to move single fingers, leaving the others at rest, is acquired at the age of about 6 years (Rey, 1952). This skill must have its sensory counterpart. The ability to classify sensation from the fingers in terms of the particular finger from which it was derived (“differential finger sensation”) ought to be detectable by appropriate testing. The four fingers, morphologically somewhat similar, are distinguishable chiefly on the basis of their positions relative to one another. In this respect they differ from other parts of the body, with the exception of the toes. The questions arise, at what stage in maturation does it become possible to perform discriminations based on the differentiation of sensations from the fingers, and does it at the same time become possible to succeed in tasks requiring an appreciation of their spatial arrangement? To answer these questions, and to make it possible to detect the postulated abilities in a reliable manner, three new test procedures were designed. They are described below, and the results obtained presented.