Fig. 3.

Bayesian behavioral model and the relationship between the contraction bias and difficulty. (A) Schematic of the Bayesian behavioral model: Prior knowledge and observations are combined to obtain two comparison beliefs, b(H) (f₁ > f₂; Higher) and b(L) (f₁ < f₂; Lower). These beliefs are compared by magnitude in order to reach a decision. The decision can be decomposed into two components: choice and uncertainty. See SI Appendix, Methods for a more accurate description of the model. (B) Model fit of the percentage of times in which the base frequency (f₁) is called smaller. The behavioral data are in gray (circles, lines), and model predictions are in green (triangles, lines). Line pairs for the 12 classes divided by the diagonal in Fig. 1D (f₁ < f₂, Upper pair; f₁ > f₂, Lower pair). Model best-fit parameter values were σ₁ = 5.5 Hz and σ₂ = 3.2 Hz. (C) Choices are made using the MAP criterion (orange line). Uncertainty is defined as 1 minus the maximum of the two beliefs b(H) and b(L) (gray line). (D) Bayesian model uncertainty predictions: Correct trials are in blue (circles, lines), and wrong trials are in red (circles, lines).