VECTOR MODEL OF SIMULTANEOUS CONTRAST FOR ACHROMATIC STIMULI

The vector model of simultaneous brightness contrast for achromatic co lours is suggested. The difference of intensities between the test and inducing fields is evaluated in subtracting neurons. The difference i s added to the test field activation if the intensity of the latter is greater than that of the inducing field and is subtracted under the o pposite conditions. The lightness of the test field is coded by a two- dimensional vector which is composed of excitations of white and grey or black and grey neurons. Single values of lightness are coded by sel ective lightness detectors.