Abstract

It is well known that after viewing a coloured stimulus the perception of subsequent stimuli is chromatically shifted in the opponent direction, because of biased output of early chromatic mechanisms. Recent studies [1,2] show that known colours of familiar objects affect the perception of those objects, biasing the white-point in the direction opposite that of the memory colour. We investigated whether familiar object colours cause an after-effect by adapting observers to greyscale images of objects with diagnostic colour, before measuring the perceived white-point of simple geometric stimuli. In control measurements the adapting images were phase-scrambled. Despite the measurements being made with judgements of simple geometric stimuli, chromatic shifts were observed relative to control measurements, consistent with adaptation to the colour implied by the objects. Our experiment was designed to eliminate potential response bias.
These results could be interpreted as adaptation of colour-signalling mechanisms via top-down input, in the context of colour constancy mechanisms in which the greyscale images are assumed to be the result of a prevailing illuminant with a colour complementary to the object colour.

1. Hansen, T., Olkkonen, M., Walter, S., & Gegenfurtner, K. R. (2006). Memory modulates color appearance. Nature Neuroscience, 9(11), 1367–8.
2. Olkkonen, M., Hansen, T., & Gegenfurtner, K. R. (2008). Color appearance of familiar objects: effects of object shape, texture, and illumination changes. Journal of Vision, 8(5), 13, 1-16.