The performance of color deficient individuals on airfield color tasks

The pseudo-isochromatic plate (PIP) test (e.g., Ishihara test) is the clinical test commonly used to assess color vision. Upon failure of this test, candidates are typically reassessed using the Farnsworth Lantern (FALANT) test to determine their fitness for occupations which require normal color vision. We were interested in determining to what extent clinical tests can predict real life color naming performance, particularly in the context of "airside drivers" (any airport vehicle operators who drive on the airfield).

There were 24 male subjects with a color vision deficiency, as defined by the Ishihara test, who participated in this study. They were further assessed using the D-15 and lantern color vision tests. All subjects then participated in two separate color naming tasks. These tasks consisted of naming surface colors and colored-lights of the type used on the airfield of the Hong Kong International Airport (HKIA).

Of the 24 subjects, 15 failed both D-15 and the FALANT tests. Out of these 15 subjects, 8 also failed the naming tasks. The FALANT test showed very good agreement (87.5%) with the Ishihara test. Similar to the Ishihara, FALANT tests had 100% sensitivity in identifying the subjects who failed the naming tasks. The agreement between the Ishihara and D-15 tests was 62.5%.

In common with previous studies, our results show that clinical tests cannot predict accurately who will fail color naming tasks of the type normally encountered in the real-life work environment. The high false positive values of the clinical tests in relation to color naming tasks suggest that people with color deficiency may not be given a fair opportunity to demonstrate their true ability in performing the task.