Assessment of the Penn anomaloscope.

The main forms of normal and anomalous human color vision can be classified by the Rayleigh match - the ratio of red and green light that matches an amber reference light. We have used a new device - the Penn Anomaloscope - to obtain Rayleigh matches for a group of normal and anomalous participants. The Penn anomaloscope exhibited a high test-retest reliability, not only giving the same diagnosis for normal and anomalous observers on different occasions but also preserving individual differences among normal observers. There was good agreement with the diagnoses given by an established commercial anomaloscope, the Oculus HMC. Using the DeMarco-Smith-Pokorny theoretical cone sensitivities for anomalous and normal observers, and our own measurements of the spectral power distributions of the primaries of the Penn anomaloscope, we modeled the settings that would be predicted for protanomalous, deuteranomalous, and normal participants. There was close agreement between the settings expected from the modeling and the settings independently obtained empirically. The Penn device is compact and portable, and it may be recommended for field studies and educational purposes.