Figure 4.

Advantage of normal trichromacy increases with distance. In panels (a and b), the difference in performance (RT or error) between the colour-deficient member and the colour-normal member of each pair was divided by the overall mean RT or error of that pair, in order to control for different overall performance and speed–accuracy trade-offs. In panel (c), the RT for the colour-deficient member of each pair in each condition is simply divided by the RT of the colour-normal member (which is a simpler analysis and also controls for differences in baseline speed with distance). This analysis could not be done reliably for error scores because there were many instances of dividing by zero or near-zero bins. The dashed and dotted lines show the subsets of results for dichromats and anomalous trichromats (each compared with their matched normal trichromat).