A Study of Ocular Functions, with Special Reference to the Lookout and Signal Service of the Navy

Fitness for lookout and signal service work in the Navy, and for night flying in aviation depends to some extent upon keenness of discrimination at low degrees of illumination. There is a wide range of individual differences in the minimum illumination required for the discrimination of the test object, both before and after dark adaptation. This range reaches 657 per cent. The two eyes of the same observer require a different amount of light, ranging from 19 to 54 per cent. of the amount required for the better eye. In only six per cent. of the cases was discrimination with the better eye more acute than with both eyes together. From Psych Bulletin 18:06:00324. (PsycINFO Database Record (c) 2012 APA, all rights reserved)