Scotopic Thresholds of Rhesus Monkeys at Different Grating Densities under Normal and Low-Protein Diets

Abstract

Scotopic thresholds of rhesus monkeys were determined over a range of luminance levels, from 1138 to 17.8 × 10−9 cd/cm2, and grating densities, from .132 to 1.58 lines per cm. The effects of a low-protein diet on these thresholds were also investigated, and standard stimulus objects within the discrimination learning situation were employed. Obtained thresholds decreased systematically from about 350 to 20 × 10−9 cd/cm, and there were no significant differences due to dietary protein level.