TY  - JOUR
PY  - 1944//
TI  - A preliminary investigation of form and motion acuity at low levels of illumination
JO  - Journal of experimental psychology
A1  - Warden, C. J.
A1  - Brown, H. C.
SP  - 437
EP  - 449
VL  - 34
IS  - 6
N2  - Four trained subjects were given tests of form acuity at retinal positions ranging from 5 to about 80 degrees of peripheral angle as well as motion acuity tests at 7 positions ranging between 5 and 55 degrees. Three levels of illumination--photopic, near-scotopic, and scotopic--were employed in securing both sets of data. Results showed that the form acuity threshold rises with increase in the peripheral angle and decrease in illumination. Since the stimuli used in obtaining the form thresholds faded out before a judgment of motion could be obtained, a larger set of stimuli was selected. These showed that the motion acuity threshold likewise rises with increase in peripheral angle and decrease in illumination. Under scotopic conditions, motion acuity is more acute at about 10 degrees of peripheral angle than at parafoveal or outer peripheral distances. (PsycINFO Database Record (c) 2012 APA, all rights reserved)<p /> 
LA  - 
SN  - 0022-1015
UR  - http://dx.doi.org/10.1037/h0062078
ID  - ref1
ER  -