Recent work suggests that fluctuations in dopamine delivery at target struc
tures represent an evaluation of future events that can be used to direct l
earning and decision-making. To examine the behavioral consequences of this
interpretation, we gave simple decision-making tasks to 66 human subjects
and to a network based on a predictive model of mesencephalic dopamine syst
ems. The human subjects displayed behavior similar to the network behavior
in terms of choice allocation and the character of deliberation times. The
agreement between human and model performances suggests a direct relationsh
ip between biases in human decision strategies and fluctuating dopamine del
ivery. We also show that the model offers a new interpretation of deficits
that result when dopamine levels are increased or decreased through disease
or pharmacological interventions. The bottom-up approach presented here al
so suggests that a variety of behavioral strategies may result from the exp
ression of relatively simple neural mechanisms in different behavioral cont
exts.