Simultaneous brightness induction as a function of inducing- and test-field luminances.

Abstract

Simultaneous brightness induction was measured in human subjects by means of a binocular matching method. The test field, an evenly illuminated disc-shaped area, and an annular inducing field which completely surrounded the test field, were presented to the observer''s right eye. A comparison field of the same size and shape as the test field was presented to the observer''s left eye. The observer made brightness matches between the test and comparison fields. With the matched luminance of the comparison field serving as an indicant of the apparent brightness of the test field, the effect of varying the luminance of the inducing field on the apparent brightness of the test field was studied for several luminance levels of the test field. Inducing fields with luminances from almost as great to greater than that of the test field depressed the apparent brightness of the test field. Possible theoretical interpretations of the results and the application of the data to the analysis of brightness constancy are discussed.