The above analysis considers only the influence of the most recent trial’s events on choice. However, the slow time course of adaptation to reversals (Figure 1E) indicates that choices must be influenced by a longer trial history. To better understand these long-lasting effects, we used a lagged regression analysis assessing how the current choice was influenced by past transitions, outcomes, and their interaction (Figure 2C). Predictors were coded such that a positive loading on, for example, the outcome predictor at lag x indicates that reward on trial t increased the probability of repeating the trial t choice at trial t + x. Past outcomes significantly influenced current choice up to lags of seven trials, with a smoothly decreasing influence at larger lags. Past state transitions influenced the current choice up to lags of four trials with, unexpectedly, a somewhat larger influence at lag 2 compared with lag 1. Also unexpectedly, although the transition-outcome interaction on the previous trial did not significantly influence the current choice, the interaction at lag 2 and earlier did, with the strongest effect at lag 2.
