Fig. 2. Assessing dichromatism in the human visual range. Geometric mean regression of segment classification estimates of sexual dichromatism in the human visual (400–700nm) range against human visual estimates (r²=0.73, N=978, P<0.0001). Segment classification scores were calculated using spectrophotometer data. Scores for each index were standardized to a mean of zero and a standard deviation of one.