When stereopsis does not improve with increasing contrast

• Published in: Vision research (Oxford) 1998-12, Vol.38 (23), p.3671-3679
• Main Authors: Wilcox, Laurie M, Hess, Robert F
• Format: Article
• Language: English
• Subjects: 2nd-order; Biological and medical sciences; Contrast; Contrast Sensitivity - physiology; Depth Perception - physiology; Dmax; Fundamental and applied biological sciences. Psychology; Humans; Non-linear; Pattern Recognition, Visual - physiology; Perception; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Psychophysics; Sensory Thresholds - physiology; Space life sciences; Stereoacuity; Vision
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/S0042-6989(98)00066-2

It is well known that stereoacuity for conventional (1st-order) stimuli improves with increasing contrast with an approximate slope of −0.5 on log–log axes (Halpern DL, Blake RR. Perception 1988;17:483–495; Legge GE, Gu Y. Vis Res 1989;29:989–1004). In the experiments reported here a variety of stimuli were used (Gabor patches, amplitude modulated stimuli and 1D noise patches) and tasks (stereoacuity and D max) to determine if 2nd-order stereopsis shows a similar square root dependence. The results consistently demonstrate that the effect of contrast on stereopsis is quite different for the 2nd-order stimuli. Increases in stimulus contrast have little effect on performance; the resulting slopes are very shallow. The pattern of results is similar when the interocular contrast ratio is varied, demonstrating that 2nd-order processing is more resilient to stimulus differences in the two eyes than 1st-order.