Aging and spatial acuity of touch.

Spatial acuity of the skin of the fingertip deteriorates markedly with age, as assessed by 2-point thresholds measured with a forced-choice method in 80 subjects between the ages of 18 and 91 years. This loss of "minimum separable" acuity appears to be pervasive, demonstrably affecting many middle-aged and a great majority of the elderly persons tested. Mean threshold was 1.95 mm for young (18-33 years), 2.68 mm for middle-age (41-63 years), and 5.03 mm for elderly (66-91 years) subjects. Over half of the variance in 2-point threshold was attributable to age (r = .74). Threshold on the arm, measured in subsets of 15 young and 15 elderly, was also age-dependent, but (reckoned as a percentage) the difference is minor compared to the finger. Analysis implies that the perception of tactile patterns, in general, and tactile reading (braille, Optacon) by the sensory handicapped, in particular, could run into age-related difficulty by reason of impairment of spatial acuity at the most basic level.