Dopamine replication in mixture model. We performed an in vivo validation by replicating the previous dopamine findings using our new multivariate mixture model. We split trials into low (0–50%), medium (60–80%), and high (90–100%) bets and examined dopamine transients at these different bet levels in response to positive and negative reward prediction errors. As per the findings reported previously for a univariate model (Kishida et al, 2016) dopamine estimates from the dual transmitter model predict dopamine encoding of prediction errors. Using two-way ANOVAs with factors RPE (negative RPE and positive RPE) and bet levels (high, medium, low) we found a significant interaction at 200 (p=0.005), 300 (p=0.0001), 400 (p=0.0016), 500 (p=0.0079), and 600 ms (p=0.02). Post hoc two-sample t-test results for each bet level and time point are illustrated (*p<0.05, ***p⩽0.001). For validation purposes, we report here, those measurements from the original cohort of 17 patients reported in Kishida et al, 2016. Data were baseline corrected to zero at 0 ms, and bar graphs depict the mean and SEM.