Fig 1. The visuomotor learning task used to validate the model.

Three colour stimuli are presented to the participants in a pseudo-random order, in particular in triplets each containing each colour exactly once. The action consists in pressing one out of five possible buttons with the right hand. The figure refers to an ideal participant who never repeats an error for the same colour and always repeats the correct action after discovering it. The four pictures refer to respectively the actions after one, two, four, and five triplets: a red cross and a green tick-mark refer to incorrect and correct colour-action sequences respectively. The colour receiving the first action in the second triplet is marked as the ‘first stimulus’ (S1), and such action is considered the as correct one for it. The colour different from S1 receiving the first action in the fourth triplet is marked as the ‘second stimulus’ (S2), and such action is considered as the correct one for it. The colour different from S1 and S2 receiving the first action in the fifth triplet is marked as the ‘third stimulus’ (S3), and such action is considered the correct one for it.