A, B, Discounting curves per medication/DBS state subgroup for €20 (A) and €30 (B), based on the indifference point at 3, 6, and 9 months. Error bars show SEs. C, Plots of the hyperbolic model in the on-DBS and off-DBS states, based on the median k-value. Shaded areas show the 25th and 75th percentile range. D, Plots of the quasi-hyperbolic model in the on-DBS and off-DBS state based on the median β and δ values. The initial linear decline represents present bias and is determined by the β parameter, whereas the subsequent exponential curve represents “patience” and is determined by the δ parameter. Shaded areas show the 25th to 75th percentile range.