Interdisciplinary studies of decision-making and motor planning

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Most psychological theories are aimed at understanding advanced aspects of human cognition. For example, studies of decision-making usually address how we make abstract choices such as selecting a career or buying a house. These often lead to theories suggesting that decisions are made within a cognitive system prior to being transmitted to the motor systems for executing the required movements a serial architecture of sensing, thinking, and then acting. However, the human brain is the product of a long history of evolution, and during most of that history, animals were faced with challenges very different from those of abstract decision tasks. In particular, most decisions in animal life are made in a real-time, dynamically changing environment that does not allow time for careful deliberation followed by action planning. I have proposed that for effective behavior in such dynamic situations, the brain uses a parallel architecture in which multiple potential actions can be specified simultaneously, one selected on the basis of current sensory information, and even during its execution other options remain under consideration in case circumstances suddenly change. This is called the “affordance competition hypothesis”. My research program is aimed at testing and further developing this general framework, and I hope to renew my NSERC Discovery Grant to support three specific aspects of that endeavor. Project 1 will aim to determine the mechanism by which changing sensory information is integrated with the growing urge and need to act. It will further explore our recently-proposed “urgency gating model” using human behavioral studies. Project 2 will develop a computational model of the distributed network implementing action selection in the primate prefrontal, premotor, and motor cortex, as well as the basal ganglia. It will be based on a novel analysis of data we have collected during neural recording experiments in my lab. I believe that this analysis reveals the properties of the dynamical system that governs decision-making, and that we can incorporate these properties into a sophisticated and realistic mathematical model of the cortical and subcortical decision-making system. Project 3 will launch a new experimental paradigm for studying situations in which decisions are made during already ongoing actions. This will involve studies in which humans continuously track a moving target while new targets occasionally present themselves. Although the task will appear continuous to the subjects, the new targets will be presented in such a way as to test specific predictions from classic decide-then-act paradigms. In this way, we will investigate which of our existing theories, developed in static laboratory situations, generalize to behavior in the real world.