Fig. 2.
Between group differences in learning and face preferences. A. Fraction correct, referenced to the ideal observer when choosing between happy and angry faces in drug and placebo conditions. Error bars are +/− 1 s.e.m. B. Difference in learning from positive and negative feedback. Error bars are +/− 1 s.e.m. Positive (Pos) is parameter α from equation 4 in supplemental methods. Negative (Neg) is parameter β from equation 5 in supplemental methods. C. Evidence vs. choice probability curves. Fraction of times participants picked the happy face, give the evidence for the happy face, under drug and placebo conditions. The evidence comes from the ideal observer model, and is given by p(θhappy >θangry) from eqn. 2.