The placebo effect is a powerful example of how expectations can shape experiences. Patients with Parkinson's disease, who have substantial loss of midbrain dopamine neurons projecting to the striatum and prefrontal cortex, show motor improvements after placebo treatment, suggesting that expectation may induce dopamine release. Schmidt et al. show that in patients with Parkinson's disease who received a placebo, the expectation of receiving the dopamine precursor L-dopa also increased reward learning, with an efficacy equivalent to that of L-dopa treatment. These findings show that the expectation of receiving dopaminergic treatment can enhance reward learning.