Figure 2.

Task outline. a, Example DMC trial. The monkey is required to fixate for 500 ms, followed by the presentation of a sample (cat or dog) stimulus for 600 ms. There is then a 1000 ms delay followed by the presentation of a test stimulus. If the test stimulus is a category match to the sample stimulus (i.e., cat–cat or dog–dog), the monkey must release a lever. If it is a category nonmatch, the monkey must continue to hold the lever until a match is presented. b, Example passive viewing trial. The monkey must fixate for 500 ms before a sample stimulus is presented. The stimulus is displayed for 600 ms while the monkey maintains fixation, followed by a juice reward upon completion of the trial.