What We will investigate how mental selection mechanisms are critical for a broad range of cognitive functions such as attending to information in the environment, planning what to do, remembering plans, or solving problems. Why A good life depends on one’s ability to solve problems when meeting them. When we solve problems, we typically do this by a sequence of actions that leads us from a starting point and to the solution. If we for example are finding our way through a maze or a new city, we will solve the problem by moving in one direction until we meet a junction. We then have to make a decision about which way to proceed. Should we go left, right, forward, or even backwards? We must select one of the four actions to move further towards our goal. If we can make the right selections of actions, we will find our way through the maze quickly. If not, we may be stuck there, maybe forever. How In this project we investigate the internal mental competition between different actions when we plan and solve-problem. We will run psychological experiments where we investigate how actions are selected. Furthermore, we will develop mathematical models that makes it possible for us to investigate the mechanisms that enable us to plan actions and solve problems. A new theoretical framework and mathematical models will enable us to study how the selection mechanisms are realized in the brain.