Deciding and revising: A unifying framework for decision making and motor control

Decision making spans a vast range of types and complexity, from choosing your partner to deciding whether to dive left or right to save a goal. Progress in a variety of fields has led to an understanding of the mechanisms that evaluate evidence and reach a decision. Studies of simple decisions have provided insight into the neurobiological mechanisms responsible for decision making in both monkeys and humans. These studies often require a choice between two possibilities, such as leftward or rightward motion of dots moving on a screen. Human and nonhuman primate experiments support a mechanism in which a decision is made when the accumulated evidence reaches a criterion level. Such an accumulation process explains both the accuracy of the decisions made over a range of difficulty levels as well as the time required to make each decision. However, a decision in the absence of an action (or the withholding of an action) has little value, and in recent years there has been substantial progress in understanding how a task goal determines the actions that will be made. In this new framework, the movement system sets up a feedback rule that determines how the commands we send to our muscles should depend on sensory inputs we receive, so as to optimizes certain criteria such as a tradeoff between effort and accuracy.

Traditionally, decision making and movement-control were believed to operate separately and sequentially, but recent evidence from cognitive psychology and neuroscience suggests a more intimate connection. A fascinating implication of this connection is that it can explain why, in the absence of additional information, a decision-maker might change his or her mind. We have recently developed a task in which we can monitor confidence in a decision and also changes-of-mind, showing that once the brain reaches a decision and commits to a choice, it can continue to analyze evidence that was in the pipeline but unavailable to impact the initial decision. Our project extends and unifies the fields of decision making and movement control with a combined behavioral, neurophysiological and theoretical approach within a common conceptual framework. Our hypothesis is that a common framework applies to the revision of both actions and ideas, and we will develop a theory of decision making and control that extends to the acts of vacillation and self-correction.