Recognition performance of subjects with color-vision deficiencies on a polychromatic sonar screen for ship navigation.

To facilitate differentiation between objects that are approaching, stationary, and moving away, these objects are represented in different colors on the screens of sonar locating devices used in ship navigation. Yellow represents stationary objects, and represents approaching objects, and green represents those objects moving away. A total of 46 subjects with normal color vision and 184 individuals with color-vision deficiencies, among them 29 deuteranopic, 100 deuteranomalous, 21 protanopic and 34 protanomalous individuals, were investigated for their ability to identify different signals. Ten different objects were presented for a period of 64 s each. As a minimal requirement it was established that 50% of the respective experimental group be capable of recognizing the objects within half of this time. Whereas 73.3% of the subjects with normal color vision could meet this requirement, none of the subjects in the different groups with color-vision deficiencies could do so. Only 16.1% of the deuteranopic subjects, 33.1% of the deuteranomalous individuals, 16.2% of the protanopic subjects, and 37.6% of the protanomalous individuals detected all objects within 32 s. No appreciable difference in the ability to recognize signals occurred among the different groups of subjects with color-vision deficiencies.