A Survey and Evaluation of Lantern Tests of Color Vision

Abstract
A survey of the lantern tests, used to evaluate the color vision of people who wish to enter occupations that require the ability to recognize colored signal lights reliably, is reported. The origin of each lantern is traced and the principal features of each are described. The available data concerning failure rate of normals, the failure rate of people with defective color vision, and the extent to which scores on lantern tests correlate with field trials are summarized. Despite the fact that lantern tests were used since the turn of the century and that some lanterns were in use for > 30 yr and some for much longer periods, the available validation data are incomplete and sometimes conflicting. Apparently, some lanterns may fail a significant proportion of normals and there may be considerable variation between lanterns in the proportion of color vision defectives that will fail. Most lanterns will pass some protanomals despite their reduced sensitivity to red light and correspondingly short visual range for red signals. The view of Cameron is supported that a more rational approach would be to make a clinical diagnosis of the type of color vision defect, to reject protanopes, deuteranopes, and protanomals and to use a lantern test only to determine which deuteranomals should be accepted.