Figure 5. Zygomaticus during Delivery (marginal means and 95% CIs).

A Liking x Drug interaction (not significant after FDR correction, p=0.09, but credible according to a Bayesian LMM) reflected zygomaticus activation for greater liking in the placebo group, and to a lesser extent also in the amisulpride group, but zygomaticus relaxation in the naltrexone group. This suggests that blocking of the opioidergic system resulted in an inverted effect of liking on zygomaticus activation, with less smiling for the most liked rewards.