Item

Abstract

The role of chromatic information in visual cognition is still unclear. Considerable neural resources appear to be devoted to the analysis of chromatic information. Yet roughly 8 of the male population are at least partially colour blind and many remain unaware of their deficiency until formally tested. We used a recognition task to assess the importance of colour information for recognition memory. During the presentation phase a series of 48 images of natural scenes was presented to subjects on a CRT display for exposure durations between 50 and 1000 msec. Display of the images was followed by a random noise mask. Half of the images were presented in colour; half in black white. The luminance component of the images remained constant. In the subsequent query phase the same 48 images were intermixed with 48 new images, and the subjects had to indicate which one of the images they had already seen in the presentation phase. We found a significant effect of exposure duration and colour on recognition performance. Subjects performed 5-10 better for the coloured than for the black white images at all exposure durations, even the shortest ones. Surprisingly, performance was not impaired for a comparison group of 31 dichromats (17 protanopes and 14 deuteranopes), who were also better for colour images. The high speed of colour processing indicates that its usefulness might lie in fast image segmentation. Colour-deficient observers seem to be able to compensate their reduced chromatic information range when viewing and analysing complex scenes.