Civilisation and Eyesight

Abstract

IN a short article on Civilisation and Eyesight which appeared in NATURE of February 12, Lord Rayleigh expresses the belief that the greater visual acuity of savages “is a question of attention and practice in the interpretation of minute indications” and is not ascribable to any possible inherent superiority in their eyes, regarded simply as optical instruments. With this conclusion probably most who have had opportunities of testing the sight of uncivilised races or read the account given by those who have undertaken such examinations, will agree. The same difference in making more or less out of an imperfect retinal image is met with in different individuals with the same degree of short sight, and otherwise subjected to similar conditions according as they have or have not been in the habit of resorting to constant optical correction of their defect. Such a cerebral elaboration of the retinal image, as it might be called, constitutes also probably the main reason for the difference between the visual acuity of children who have only just learnt to read the letters of the alphabet and adults, which our ordinary tests so frequently show.