The bimodality of unique green revisited.

Unique green measurements were obtained from 50 females and 50 males under eight different experimental conditions. Combinations of two different test sizes (0.25 and 1.0 deg) and four different background fields (none, 62.5, 250, and 1000 td) comprised the experimental conditions under which unique green measurements were made. Group and gender frequency distributions of the unique green loci were examined for the eight experimental conditions. Differences in the shape of the frequency distributions were noted for the different test sizes and backgrounds as well as for gender, but none of the experimental parameters appeared to elicit a statistically significant bimodal distribution.