Mental graphs structure the storage and retrieval of visuomotor associations

Much of human memory takes the form of cognitive graphs that allow us to relate and generalize knowledge. The influence of structured memory in the motor system is less clear. Here, we examine how structured memory representations influence action selection when responses were retrieved from newly learned, hierarchical visuomotor maps. Human subjects (N = 182) learned visuomotor mappings with (or without) an imposed latent structure that linked visual stimulus features (e.g., color, shape) to intuitive motor distinctions, like hands and pairs of fingers. In subjects who learned structured visuomotor mappings, transitional response times indicated that retrieving the correct response from memory invoked “traversal” of a tree-like mental graph. Forced-response experiments revealed similar computations within individual trials. Moreover, graph-like representations persisted even after multiple days of practice on the visuomotor mappings. Our results point to direct links between internal computations over structured memory representations and the preparation of movements.