Fig. 25 Scores on the Farnsworth D-15 panel test for deutan and tritan color defectives. For the deutan, caps 1 and 15 look more alike than caps 1 and 2 and are consequently placed side-by-side by deutan observers. Caps 1 and 15 lie along the same confusion axis of the deutan (see color in Fig. 4). By contrast, the tritan sees caps 7 and 15 as more alike than caps 7 and 8. The orientation of the errors is indicative of the type of color defect.