We make decisions almost every moment of our life, some are small and less significant, and some are major and have crucial influence on the course of our lives. Decisions rely on information gathered previously (memory), which is weighted with the current flow of information (sensory perception), consideration of the possible alternatives, and reasoning to reach a final decision – usually resulting in an action or lack thereof. Furthermore, decisions may be driven by external cues but also depend on internal volitional and stochastic processes. The groups studying decision making in the department use several techniques to shed light on the different mental processes involved in this decision making. We rely on psychophysical studies to unveil perceptual mechanisms in humans, behavioral and functional imaging studies of the human brain during memory formation and active decisions, and electrophysiological studies in animals as well as diagnostic intra-cranial recordings in patients -- to unveil the neuronal networks involved in these processes. We combine expertise from different fields, such as behavioral paradigms from cognitive psychology, electrophysiology in behaving animals and functional imaging in humans, computational approaches and modeling, and believe that only a multidisciplinary integrative approach can help decipher the complex process of decision making.