Variations in normal trichromatism

Abstract

Analysis of large field colour matching data has shown that the spectral positioning of cone pigments varies discretely among normal trichromats. The Rayleigh matches made by male observers appear to fall into two groups whereas those of females are trimodally distributed with the majority of colour matches occurring in an intermediate group not found in males. (Neitz and Jacobs, 1989). In order to investigate whether subgroups of normal trichromats can be detected using a 3° matching field we have examined the Rayleigh matches of 100 male and 100 female observers using the Mark I Nagel Anomaloscope. A strict examination procedure was used to determine the mean match and matching range for each observer. Our results show that it is possible to detect 3 groups of observers within the normal distribution of results for both males and females. For females the intermediate group comprises the majority of observers while for males this group is relatively small. On average, females show a larger matching range than males and this factor is influential in placing the majority of mean matches towards the centre of the normal distribution.