The (null) effect of real-face adaptation on curvature judgment (experiment 2). a , Psychometric functions from a naive subject under the following conditions. 0-c, No adaptation baseline (blue); c′-c, adaptation to the concave curve, whose curvature, length, and contrast matched those of the saddest face (green); f-c, adaptation to the saddest face (red); m-c, adaptation to the mouth isolated from the saddest face (black). For each condition, the fraction of convex responses was plotted as a function of the curvature of the test curves. b , Summary of all four subjects' data. For each condition, the average PSE relative to the baseline condition and the SEM were plotted. The p value shown for each condition in the figure was calculated against the baseline condition using the two-tailed paired t test. Unlike the corresponding cartoon-face result in Figure 4, the f-c condition did not generate a significant shift of the PSE from the baseline.