Brain regions from which it was possible to "read out" peoples' intentions. In specific regions fine-grained patterns of brain activity showed slight differences depending on whether a person was preparing to perform an addition or a subtraction. From activity patterns in the green regions it was possible to read out covert intentions before subjects began to perform the calculation. From the regions marked in red it was possible to read out intentions that were already being acted upon. Credit: Bernstein Center for Computational Neuroscience Berlin