Effect of congenital blindness on the semantic representation of some everyday concepts.

This study explores how the lack of first-hand experience with color, as a result of congenital blindness, affects implicit judgments about "higher-order" concepts, such as "fruits and vegetables" (FV), but not others, such as "household items" (HHI). We demonstrate how the differential diagnosticity of color across our test categories interacts with visual experience to produce, in effect, a category-specific difference in implicit similarity. Implicit pair-wise similarity judgments were collected by using an odd-man-out triad task. Pair-wise similarities for both FV and for HHI were derived from this task and were compared by using cluster analysis and regression analyses. Color was found to be a significant component in the structure of implicit similarity for FV for sighted participants but not for blind participants; and this pattern remained even when the analysis was restricted to blind participants who had good explicit color knowledge of the stimulus items. There was also no evidence that either subject group used color knowledge in making decisions about HHI, nor was there an indication of any qualitative differences between blind and sighted subjects' judgments on HHI.