Figure 11.

Predictions for the data from the present Experiment. Data points are the average contrast thresholds of three observers for 60 different conditions (three targets × four eccentricities × three background contrast levels for two kinds of background; the 0% background contrast is a uniform field, and hence, the black points are the same in the upper and lower plots). Error bars represent ±2 standard errors (across observers). Parameter values: k_c = 1, k_s = 10.1, w_c = 0.53, ρ = 2.4, β = 1.685, P₀ = 4.45E−4, σ_l = 1°, k_b = 25, w_b = 0.962. The first six parameters are the same as in Figure 10 except for P₀, which accounts for (modest) differences in overall sensitivity between groups of observers (RMS error = 2.27 dB).