Citation

Israel HE. J. Exp. Psychol. 1923; 6(3): 223-233.

Copyright

(Copyright © 1923, American Psychological Association)

DOI

10.1037/h0071941

PMID

unavailable

Abstract

The purpose of this investigation was to compare, at low intensities of illumination, the relative degrees of accuracy of accommodation and convergence in the discrimination of visual distances. A small white bead, the standard, was set at a distance of 75 cm. from the eye, and O moved another bead until it and the standard appeared equally distant from him. Adjustments were first made with both eyes to give indication of the effectiveness of accommodation and convergence together, and then with one eye screened to determine the effectiveness of accommodation alone. The results show that at an illumination of 0.0117 foot-candle, the average error for accommodation alone is 1/23 of the standard distance and that for accommodation plus convergence is 1/58 of the standard distance. As the intensity of illumination is reduced the average error for both accommodation alone and accommodation plus convergence gradually increases. At a point near the lower visual threshold accommodation alone breaks down while convergence shows little change in the rate of increase in error. From Psych Bulletin 21:01:00034. (PsycINFO Database Record (c) 2012 APA, all rights reserved)