What dictates the extent of evidence accumulation in human decision making?

The mechanisms that the brain uses to translate sensations into actions are fundamental to general cognitive function and understanding them is vital for understanding and treating impaired information processing in clinical conditions. The vast majority of research on decision making relies on models in which evidence is accumulated over time up to a criterion amount, but it is increasingly being asked, to what extent does accumulation really underlie most decisions, and what factors determine its extent? In our proposed research, we will resolve these questions using a powerful new approach in which neurophysiological signals reflecting decision formation are traced at multiple levels of processing in the human brain and used to construct and constrain mathematical models of the decision process. This work will gain fundamental insights into core cognitive operations underlying flexible behaviour and furnish new methods and metrics for use in clinical investigations.