Figure 3.

Neuronal probability distortion corresponding to an S-shaped function. a, Activation in ventrolateral prefrontal cortex covarying with an S-shaped probability weighting function (peak at 54/32/14; whole-brain correction; z = 3.6) (supplemental Table S1, for further regions, available at www.jneurosci.org as supplemental material). An S-shaped activation profile was tested by comparing activation increases from p = 0.25 to p = 0.75 against increases from p = 0.0 to p = 0.25 and p = 0.75 to p = 1.0. Activation corresponded significantly better with distorted than linear probability coding (P < 0.05). b, Averaged signal changes as a function of probability at peak voxel shown in a. Error bars correspond to SEM. c, Relation of ventrolateral frontal probability distortion to individual behavioral probability distortion at peak voxel shown in a. See Figure 2 c for further explanations.