Summary and conclusions, extract from: Examination of the Williams Lantern as a test for color vision

Abstract

The Williams Lantern was tested on 75 normals and 25 color deficients, using a variety of combinations of size of apertures, numbers of light filters and brightness. The total number of judgments was 12,600. Tests were conducted in dark and in light surroundings. Defective color vision of the observers was scored by using four or more standard tests for color vision: Pseudo-isochromatic tests, Dimmick Anomaloscope, Royal Canadian Navy Lantern, and Farnsworth Dichotomous Test B-20. Scores were difficult to interpret. Normal observers and moderately color deficient observers made similar responses. Such interpretations as were possible correlated poorly with present standard tests. The machine was found awkward and confusing to operate.