Colour-cueing in visual search

Several studies have shown that people can selectively attend to stimulus colour, e.g., in visual search, and that preknowledge of a target colour can improve response speed/accuracy. The purpose was to use a form-identification task to determine whether valid colour precues can produce benefits and invalid cues costs. The subject had to identify the orientation of a "T"-shaped element in a ring of randomly-oriented "L"s when either two or four of the elements were differently coloured. Contrary to Moore and Egeth's (1998) recent findings, colour-based attention did affect performance under data-limited conditions: Colour cues produced benefits when processing load was high; when the load was reduced, they incurred only costs. Surprisingly, a valid colour cue succeeded in improving performance in the high-load condition even when its validity was reduced to the chance level. Overall, the results suggest that knowledge of a target colour does not facilitate the processing of the target, but makes it possible to prioritize it.