Participants are required to sort stimulus cards based on either shape or colour. They are first instructed to sort based on one dimension (colour) in a trial, and then it switches to the other (shape) in the following trial. "Switch" trials are also used where the participant must change back and forth between rules within a single trial. Unlike the WCST, the rule is explicitly stated and does not have to be inferred. The task measures how flexible participants are to changing rules. This requires participants to shift between dimensions of sorting.