In the main text we compared a "full" fixed thresholds diffusion model to a "simple" collapsing thresholds diffusion model -which we believe is both the most theoretically interesting and practical comparison for the reasons outlined in the main text. The "full" fixed thresholds model includes between-trial variability in drift rate, starting point, and non-decision time, while the "simple" collapsing thresholds model did not contain betweentrial variability in any parameters. However, in the cases where the collapsing thresholds model was found to be superior, our comparison leaves two potential explanations for why the collapsing thresholds model provided the better DIC value: either 1) the collapsing thresholds were able to capture certain aspects of the data, or 2) the best model was actually a fixed thresholds "simple" diffusion model, and the fixed thresholds model lost in the complexity-corrected DIC calculation because of the additional flexibility provided by the between-trial variability parameters that was not actually required to adequately account for the data.In order to address this potential limitation, we also tested a "simple" variant of the fixed thresholds diffusion model to the data of each experiment, in the same manner as the models compared in the main text. The comparison of all three models (collapsing thresholds, "full" fixed thresholds, "simple" fixed thresholds) on DIC weights for each experiment can be seen in Figure S1. For Experiment 2 (the deadline experiment), no participant had any appreciable weight in favor of the simple fixed thresholds diffusion model, meaning that its inclusion had no impact on the results. For Experiment 1 (reward rate emphasis), most participants had no weight in favor of the simple fixed thresholds diffusion model, and the minority of participants that had non-zero weight did not change the trends, again meaning that its inclusion again had very little impact on the results. However, for Experiment 3 (speed emphasis), a considerable number of participants showed PASSING TIME IN DECISION-MAKING