Extended Data Fig. 6: Parameter estimates for HDDM, DDM, and UGM.

(Associated with Fig. 5 of the main text). (a-j) Estimates from the full HDDM of hierarchical parameters (μ) for each monkey (solid lines in the muscimol experimental condition; dotted lines for monkey S in the saline experimental condition, we did not collect data from the RT task for monkey B in the saline condition). 95% credible intervals with 2.5th and 97.5th quantile boundaries of hierarchical parameters provided by shading for the muscimol condition and smaller dot-dashed lines for the saline condition. Also shown are individual session parameter estimates for monkey S’s muscimol data (upward-pointing triangles), monkey B’s muscimol data (circles), and monkey S’s saline data (downward-pointing triangles). Estimates were obtained from the median posterior distributions of each parameter. a, Estimates of the HDDM session-level drift rate offset (Δ) and hierarchical drift rate offset (\(\mu _{\Delta}\)) for monkey S (pre BF = 0.08, post BF = 3.19 ×10⁶, 99.7% probability of decrease pre to post). b, Same as in a but for monkey B (pre Bayes factor BF = 0.14, post BF = 17.87, 99.0% probability of decrease pre to post). c, Estimates of the HDDM session-level start point (w) and hierarchical start point (\(\mu _w\)) for monkey S (post BF^-1 = 11.51, 95.1% probability of a proportional start point bias away from the IF from pre to post). d, Same as in c but for monkey B (post BF^-1 = 2.82, 70.6% probability of a proportional start point bias towards the IF from pre to post). e, Estimates of the session-level non-decision time (τ) and hierarchical non-decision time (\(\mu _\tau\)) for monkey S (94.5% probability of an increase from pre to post). f, Same as in e for monkey B (97.0% probability of increase pre to post). g, Estimates of the session-level symmetric boundary (a) and hierarchical symmetric boundary (\(\mu _a\)) for monkey S (78.9% probability of an increase from pre to post). h, Same as in g but for monkey B (95.2% probability of increase pre to post). i, Estimates of the session-level lapse proportion (λ) and hierarchical lapse proportion (\(\mu _\lambda\)) for monkey S (72.5% probability of increase from pre to post). j, Same as in i but for monkey B (54.0% probability of increase pre to post). (k-l) The parameter estimates obtained from fitting the DDM and the UGM to the pre- and postmuscimol data for monkey S (panel k) and monkey B (panel l). The first row describes the model that was fit (DDM or UGM) and which data session (pre or post) was used to fit the model. The next 11 rows represent the drift rate parameter estimates (\(\delta _k\)) in evidence units/sec for the DDM or evidence units/ms for the UGM, for the k = 11 conditions (-24%, -17%, -10%, -3%, -5%, 0%, 5%, 3%, 10%, 17%, 24% coherences). The next row shows the drift rate offset (Δ). This parameter was not explicitly fit in the non-hierarchical DDM and UGM, but rather calculated as the mean of the all the drift rates across all coherences for toIF and awayIF directions that were estimated from fits. The drift rate offset decreased from pre- to postmuscimol for both DDM and UGM and for both monkeys (difference in monkey S, 0.53 evidence units/sec decrease for DDM, 2.19 evidence units/ms decrease for UGM; monkey B, 0.83 evidence units/sec decrease for DDM, 3.30 evidence units/ms decrease for UGM). The next row shows the proportional start point parameter w, defined as the proportion of the distance between the upper and lower bound. For monkey S, the start point parameter had slightly decreased from pre- to postmuscimol in both the DDM (0.06 decrease) and UGM (0.02 decrease), indicating the start point moved closer to the awayIF decision bound, and for monkey B, the start point parameter slightly increased in the DDM (0.04 increase) and UGM (0.02 increase), indicating the start point moved closer to the toIF decision bound. The next row shows the bound height parameter a, defined as the distance between the upper and lower bounds. For both monkeys, but more prominent in monkey B, the bound parameter had slightly increased from pre to post in the DDM (monkey S, pre to post increase of 0.03 decision units; monkey B, pre- to postmuscimol increase of 0.07 decision units), whereas the bound was fixed in the UGM (Supplementary Note). The row after shows the non-decision time 𝜏, in seconds, where we see a slight increase in the DDM (0.03 sec increase) and UGM (0.001 sec increase) for monkey S and a greater increase in the DDM for monkey B (0.11 sec increase), but not for the UGM (0.03 sec decrease). The last row shows the urgency slope estimates for the UGM, m, decreasing slightly with muscimol for monkey S (0.07 urgency units/ms), and decreasing more for monkey B (0.23 urgency units/ms).