Cite as:
Lucassen M P, Cornelissen F W, Tiggelaar E L, Vladusich T, 2006, "Achromatic colour matching with different contrast polarities and magnitudes: Experiments and modeling" Perception 35 ECVP Abstract Supplement

Achromatic colour matching with different contrast polarities and magnitudes: Experiments and modeling

M P Lucassen, F W Cornelissen, E L Tiggelaar, T Vladusich

We conducted experiments to examine how the visual system integrates edge information to encode surface brightness. Subjects set the luminance of a test disk to appear the same brightness as a reference disk surrounded by a ring on a common background. We varied the contrast polarities and magnitudes of inner and outer edges in the disk - ring configuration. Our main new finding is that when the inner and outer edges did not share the same contrast polarity, subjects often set the luminance of the test disk to match the polarity of the outer edge, particularly when outer edge contrast was relatively high. All the data were quantitatively modeled with a theory in which weighted edge signals are spatially summed to determine surface brightness. The modeling results generally support the idea that the inner edge partially blocks the influence of signals from the outer edge. Departures from blocking (enhancement of the induction signal) coincide with instances in which subjects matched the polarity of the test disk to the outer reference edge. We also show that the value of the blocking parameter must vary with either the contrast of the outer edge or the luminance of the background.

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