Contrast discrimination under temporally varying contrast conditions

• Published in: Perception & psychophysics Vol. 62; no. 5; pp. 1039 - 1050
• Main Authors: DANNEMILLER, J. L, STEPHENS, B. R
• Format: Journal Article
• Language: English
• Published: Austin, TX Psychonomic Society 01.07.2000
• Subjects: Biological and medical sciences; Contrast Sensitivity; Discrimination Learning; Fundamental and applied biological sciences. Psychology; Humans; Pattern Recognition, Visual; Perception; Perceptual Masking; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Psychophysics; Time Perception; Vision; Human; Vision; Perception; Masking; Experimental study; Psychophysics; Time analysis; Contrast; Stimulus discrimination
• ISSN: 0031-5117; 1532-5962
• DOI: 10.3758/BF03212087

Psychophysical contrast discrimination of a 0.8-cpd vertical grating was tested using a paradigm that alternated test and masking gratings at 8 Hz. Masking contrasts were lower than, equal to, or higher than the test contrasts. Six test contrasts were combined factorially with six masking contrasts to generate a series of six contrast increment threshold versus test contrast curves (tvc curves). A particularly simple relationship existed between these curves. The curves could be brought into alignment by shifting them diagonally by the ratio of their masking contrasts. It is shown that this behavior is predicted by a model in which contrast gain is set by the average of the test and masking contrasts coupled with a simple model of contrast discrimination. Contrast gain control integrates contrast over a period of at least 125 msec, and contrast discrimination is a function of this time-averaged contrast.