Linear separability and redundant colour coding in visual search displays

Subjects sought a unique target shape in a display of distractor shapes under three colour coding conditions. In the no colour coding condition ( NCC ) all shapes shared the same colour. In the two colour-coded conditions, the target was uniquely and redundantly colour coded with a colour whose CIE 1976 UCS chromaticity coordinates were either linearly separable ( LS ) or not linearly separable ( NLS ) from the set of distractor chromaticity coordinates. Performance was optimal under LS coding, was reduced under NLS coding and was least efficient in the NCC condition. We discuss the implications of these results for refining colour selection algorithms and for colour coding in situations where the gamut of available colours is limited. © 1997 Elsevier Science B.V.