Abstract

Simultaneous brightness contrast, or contrast enhancement, was studied using foveally viewed points of light as stimuli. Threshold and binocular brightness-matching techniques were used. When two stimuli are shown together, the presence of the second has two effects upon the brightness of the first. (a) The brightness is augmented, as if by the addition of a proportion of the light from the second stimulus. The proportion declines with separation of the two simuli. (b) As stimulus intensity increases, brightness rises at a slower rate when the second stimulus is present. Effect (b) eventually overbalances (a). When seven stimuli are shown together, the (a) effects sum linearly. No clear pattern of summation is detected for the (b) effects.

© 1965 Optical Society of America

Relation of Brightness Contrast to Inducing Stimulus Output*

James P. Thomas
J. Opt. Soc. Am. 53(9) 1033-1037 (1963)

Relation of Increment Thresholds to Brightness and Luminance*

Tom N. Cornsweet and Davida Y. Teller
J. Opt. Soc. Am. 55(10) 1303-1308 (1965)

Intensity–Time Relationship at Threshold for Spectral Stimuli in Human Vision*

H. G. Sperling and C. L. Jolliffe
J. Opt. Soc. Am. 55(2) 191-199 (1965)

Temporal Summation of Positive and Negative Flashes in the Visual System*

Mitsuo Ikeda
J. Opt. Soc. Am. 55(11) 1527-1534 (1965)

Light Adaptation and the Brightness of Brief Foveal Stimuli*

Judith Wheeler Onley
J. Opt. Soc. Am. 51(6) 667-673 (1961)