Perceptual decision making is the act of choosing one option or course of action from a set of alternatives based on the avail¬able sensory evidence. Thus, when we make decisions, sensory information must be interpreted and translated into behavior. Decision-making research has resulted in mathematical models of the assumed underlying cognitive processes and sequential sampling models are particularly successful in explaining response time data and accuracy in two-choice reaction time tasks. Recent studies in monkeys and humans have begun to model not only psychophysi¬cal but also neurophysiological data as a diffusion-to-barrier process providing a quantitative link between behavior (decision outcome) and neural activity (decision processing). In my talk I will discuss how we can use this framework to better understand the neurocognition of human decision making. Specifically, I will discuss a) results of a recent TMS study on the role of the dorsolateral prefrontal cortex in perceptual decision making, b) how human decision makers adapt thresholds to maximize reward in a perceptual decision-making task, and c) whether the mechanisms identified for perceptual decision making generalize to value-based decisions.