The glare effect and the perception of luminosity

The impression of self-luminosity in the glare effect was studied in two ex periments. In experiment 1 the target (CS) was set to the highest luminance of the field and subjects were asked to adjust the luminance ramp of the i nducers (R) against five backgrounds (B) to the point where they began to s ee CS as self-luminous. It was found that there is a linear relationship be tween background and luminance ramp. Another group of subjects carried out the same task in experiment 2, but this time CS and R were linked together so that CS would always have the same luminance as the highest luminance le vel of R, as adjustments were performed. It was found that: (i) adjustments were always lower than the highest luminance available; (ii) the linear re lationship between background and luminance ramp was confirmed; (iii) obser vers reported a compelling impression of self-luminous grays. Data are disc ussed in relation to Bonato and Gilchrist's model for the perception of lum inosity. The authors advance the hypothesis that luminance ramps are used a t an early stage of encoding for the perception of luminosity.