Figure 7.

Trade-off between discrimination and constancy for change in surface ensemble. (Left) The plot shows the trade-off between C versus in the same format as the left panel of Figure 5. When the adaptation parameters are chosen to optimize discrimination () for the test environment (surface ensemble 2), constancy performance () is poor (lower right end of each set of connected dots). When the adaptation parameters are chosen to optimize constancy, discrimination performance is poor (upper left end of each set.) The connected sets of dots show how performance on the two tasks trades off for five noise levels σ_n = 0.01, 0.025, 0.05, 0.075, 0.10. Surface ensemble parameters and illuminant intensty are given in the caption for Figure 6. In evaluating , the adaptation parameters used for computing responses in the reference environment (surface ensemble 1) were held fixed at g = 0.02045 and n = 4.5. These parameters optimize discrimination performance for the reference environment when σ_n = 0.05. (Right) Equivalent trade-off noise plotted against noise level σ_n.