Figure 7.

Human subjects exhibit undermatching in a dynamic foraging task. A, Log-choice ratio as a function of log-reward ratio for young control subjects. Slope = 0.424. B, Log-choice ratio as a function of log-reward ratio for elderly control subjects. Slope = 0.285. C, Log-choice ratio as a function of log-reward ratio for patients with Parkinson's disease off dopaminergic medications. Slope = 0.215. D, Log-choice ratio as a function of log-reward ratio for patients with Parkinson's disease on dopaminergic medications. Slope = 0.300. In all panels, the black solid line corresponds to the best fit line and the dotted line corresponds to unity.