Appendix 3—table 2. Learning rate analysis.

Main effects and interactions not involving the factor drug. Note that the learning type x volatility interaction is consistent with previous studies of experienced-value learning which have reported higher learning rates in volatile relative to stable environments (Behrens et al., 2007; Behrens et al., 2008; Browning et al., 2015; Krugel et al., 2009; Nassar et al., 2010).

Main effect/interaction	Statistics	Further information
Learning type	F(1,100) = 65.409, p < 0.001	$\alpha$direct (${\displaystyle \overline{x}\left({\sigma }_{\overline{x}}\right)}$ = 0.328(0.014)) > $\alpha$inferred (${\displaystyle \overline{x}\left({\sigma }_{\overline{x}}\right)}$ = 0.194(0.010))
Learning type x volatility	F(1,100) = 4.882, p = 0.029	$\alpha$vol_experienced (${\displaystyle \overline{x}\left({\sigma }_{\overline{x}}\right)}$= 0.341(0.017)) > $\alpha$stable_experienced (${\displaystyle \overline{x}\left({\sigma }_{\overline{x}}\right)}$ = 0.315(0.015); F(1,100) = 3.916, p = 0.051). No significant difference between $\alpha$stable_inferred (${\displaystyle \overline{x}\left({\sigma }_{\overline{x}}\right)}$ = 0.201(0.012)) and $\alpha$vol_inferred (${\displaystyle \overline{x}\left({\sigma }_{\overline{x}}\right)}$ = 0.187(0.011); F(1,100) = 1.675, p = 0.199)
Learning type x group	F(1,100) = 4.097, p = 0.046	$\alpha$social (${\displaystyle \overline{x}\left({\sigma }_{\overline{x}}\right)}$ = 0.161(0.014)) < $\alpha$non-social (${\displaystyle \overline{x}\left({\sigma }_{\overline{x}}\right)}$ = 0.227(0.014)) for inferred (F(1,100) = 11.349, p = 0.001). No difference between groups for experienced (social ${\displaystyle \overline{x}\left({\sigma }_{\overline{x}}\right)}$0.329(0.021), non-social ${\displaystyle \overline{x}\left({\sigma }_{\overline{x}}\right)}$ 0.328(0.020); F(1,100) = 0.002, p = 0.966)