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Fig. 13.7. Contour integration performance in humans and in PGLISSOM. The model's performance was measured as the average correlation coefficient between the MUA sequences in the salient contour, calculated over two trials, each with a different input example (left y axis). Human performance was measured as the percentage of correctly identified contours (right y axis; data by Geisler et al. 2001, root-mean-square (RMS) amplitude 12.5, fractal exponent 1.5, which is the closest match with the PGLISSOM input configuration). The x-axis is the orientation jitter in degrees, and the error bars indicate ±1 SEM in the model (no error measures were published for the human data). In both humans and the model, contour integration is robust up to 30^o, but quickly breaks down as the orientation jitter increases (the difference between 30^o and 50^o is significant with p < 10^-4; the other differences are not significant with p > 0.1).