TASK CONSTRAINTS AND VISUAL FEATURE BINDING

With these techniques two coloured letters are briefly presented, in a preview field. Following a short blank interval, a single coloured le tter (the target) is presented. In the first experiment, reported here , subjects named the target letter, and in the second they named the t arget's colour. In neither of the experiments did the colour relations hips between the target and preview items influence performance, but i n both cases the shape relationships were important. Further experimen ts explored the notion that performance in the tasks was only an imper fect reflection of underlying perceptual processes because of the cons traint of having to name the letters. When subjects were presented wit h unfamiliar characters and named the target's colour, then the colour relationships in the displays were important; residual effects of sha pe preview were also found. In final studies visually similar letters were used and different groups of subjects either named the target let ter or the colour of the target. Of main interest was that the colour relations between the items exerted an effect when subjects named the target's colour. The theoretical and methodological implications of th ese results are discussed and the limitations of the original experime nts are considered in the light of the reported findings. (C) 1998 Els evier Science B.V. All rights reserved.