Fig. 3.

Comparison of models in experiment 1. Circles and error bars represent mean and SEM of subject data. Shaded areas represent SEM of model fits. (A) Proportion “different” responses as a function of sample SD for optimal and suboptimal models. (B) Bayesian model comparison. Each bar represent the log likelihood of the optimal model minus that of a suboptimal model. (C) The decision criteria (Left) and the internal noise levels (Right) for the best-fitting BC model are nearly identical to those of the best-fitting optimal-observer model. This suggests that the human criteria are close to optimal.