Cite as:
Stockman A, Smithson H, Aboshiha J, West P, Ripamonti C, 2007, "Colour slew-rate: Chromatic pathways are limited by a maximum rate at which they can signal changes in colour" Perception 36 ECVP Abstract Supplement

Colour slew-rate: Chromatic pathways are limited by a maximum rate at which they can signal changes in colour

A Stockman, H Smithson, J Aboshiha, P West, C Ripamonti

At low to moderate flicker frequencies (4 to 10 Hz), the overall mean colour appearances of M- and L-cone-isolating sawtooth stimuli depend on whether the direction of the sawtooth is rapid-on (|\|\|\|\) or rapid-off (/|/|/|/|). Rapid-on-L-cone and rapid-off-M-cone sawtooth stimuli appear greener, while rapid-off-L-cone and rapid-on-M-cone sawtooth stimuli appear redder, even though they have the same mean chromaticities. These changes can be explained by supposing that chromatic mechanisms are better able to track the slowly changing phase of the sawtooth than its fast phase. Thus, their mean output will always be skewed in the direction of the slow change. By investigating how colour appearance depends on the slopes and amplitudes of the sawtooth waveforms we can determine the temporal properties of the underlying chromatic mechanisms. Our results are consistent with a simple model of red - green colour-opponent processing that is limited by a maximum rate of change in the colour signal from red to green or vice versa (the colour 'slew-rate').

[Supported by The Wellcome Trust, Fight for Sight.]

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