Fig. 2.

Columbia University Primate Cognitive Battery (CUPCB) spatial working memory task. A number of identical geometrical shapes were presented simultaneously on the monitor. Subjects touched each spatial position once to complete the trial. Successive touches to a position that differed from the current position produced positive visual/auditory feedback. Touches that were not directed at a near position resulted in negative visual/auditory feedback. Items could be touched in any order. A new set of objects, in new locations that were randomly selected, were presented on each trial. The subject had to select each stimulus in turn without repeating an earlier selection. Between selections, the subject had to return to the centre and select a ‘reset’ stimulus.