Evaluation of the Stereo Optical Co. Farnsworth Lantern (FALANT) Color Perception Test: A Specification and Performance Comparison with the Original FALANT

The Farnsworth Lantern color perception test (FALANT) has been the U.S. Navy's test for color vision since 1954. It is a reliable and an easy to administer test that separates those with good color vision from those who cannot make accurate color judgments. With the need to purchase additional lanterns while minimizing the cost, the Defense Personnel Support Center sought a less expensive alternative to the original lantern manufactured by the Macbeth Munsell Corp. The Stereo Optical Co. submitted to the Navy a prototype version for examination using less expensive plastic, rather than glass, filters. NSMRL was selected as the Navy's test facility and purchased three prototype lanterns from the Stereo Optical Co. for thorough examination. The colorimetric qualities of the lanterns' stimulus lights were measured and the color filter combination adjusted by the Stereo Optical Co. until the major color and luminance requirements were met. A second Navy laboratory was contracted to perform physical tests on the plastic color filters to assess the effects of environmental aging due to heat, humidity, and tungsten light exposure. Negligible aging effects were found. Finally, 20 color vision normals and 78 color vision defectives were tested on both the original version and the Stereo Optical Co. prototype lantern, and additional tests were administered that assessed type and degree of color vision defect. Pass/fail scores and error scores for the various categories of color vision defectives were highly similar for both lanterns. Within the context of the testing administered (for example, assuming no change in the manufacture of the lanterns, using the same lamps and filter combinations), it is highly probable that the Stereo Optical prototype version of the FALANT will perform as well as the original FALANT.