Figure 3. Preferential selection between superimposed surfaces due to color differences.

A. Open circles represent mean normalized pursuit (bars: SEM) for each distance between the two colors of each of the six color pairs tested. For each color pair, there was a dominant, selected color. The pattern of results suggests a color hierarchy for selection going from blue (weakest) to yellow to green to red (strongest). B. Pursuit increases as the color space distance for the color pair increases (order of pairs same as in A). A regression analysis revealed a significant and strong relationship between the distance in color space of the two surfaces and pursuit (R² = 0.9428, F = 65.96, p = 0.0013). The equation for the regression line is: y = 1.78(x) – 0.079.