Abstract
We previously described an individual, QP, who developed a selective deficit in colour working memory and imagery subsequent to a closed head injury. Most surprising was the fact that this deficit appeared to affect her ability to recall or imagine red but not blue. In the present study, we conducted a comprehensive assessment of QP's colour discrimination performance (Cambridge Colour Vision Test). This test revealed that the axis ratio(1.5) and length(0.0098) of QP's colour discrimination ellipses, as well as the lengths of the protan(0.004), deutan(0.004) and tritan(0.006) confusion vectors, were all within the normal range. To determine how specific her colour memory deficit was, we repeated our original delayed match-to-sample colour memory task using two new hues: green and yellow. QP's ability to recall both of these hues over an 8 s delay was dramatically impaired. Unlike memory for red, which we had previously shown was most affected when the target and distractors were quite similar in hue, QP's difficulties with green and yellow were evident even when target and distractor were perceptually quite different. Together with the previously reported data, the present findings suggest that QP's memory losses are asymmetrical about the colour axes, with the colour memory deficit for green exceeding that for red, and that for yellow exceeding that for blue. These data suggest that, consistent with recent suggestions of functional specialization for memory of different object categories and the perception of colour categories, there may be functional specialization for memory of different colour categories.