On Age and Illumination in Relation to Visual Performance

Abstract

A number of male subjects whose age distribution was within the range 19–47 years, and who were all able to read J.I., were given tasks visually comparable to various practical forms of “close work.” The performances recorded at different illuminations, ranging from 0.5 1m./ft.² to 512 lm./ft.², are analysed to show the effect of advancing age. It is shown that performances of each of the visual tasks declines from early adulthood, whatever the illumination. The effect of varying illumination over the range studied increases as age does, and also as the size of detail and the contrast in the work is reduced. It appears that equal performance by the youngest and oldest subjects is possible only if the young are handicapped by low illumination. The decline observed is discussed with reference to other findings for persons of similar age distribution. The paper shows the importance of providing high illumination for “middle-aged” persons doing fine work, but attention is also drawn to the apparently greater effectiveness of suitable optical aids.