Do chimpanzees take their time to study what they need to remember? (#611)
While many studies have used touch screen tasks to investigate metacognitive monitoring in nonhuman primates, few studies have investigated metacognitive control. Here, in the context of a serial learning task, we studied whether a chimpanzee would take more time to study a set of items when he needed to remember them than when he did not. During training trials, the subject was presented with five items (color photographs) in random locations on a black background on a touch screen. If the items were touched in correct order, the subject was rewarded, if any item was touched too early, the subject was not rewarded and instead, there was a timeout. In the testing phase, the subject was presented with regular trials (identical to training trials), as well as memory trials. Memory trials were presented on a white (rather than black) background and correctly touching the first item of the list resulted in the remaining items being covered by checkerboard patterns for the rest of the trial. During the test phase the subject received both regular and memory trials with three, four and five items. In line with the idea that chimpanzees exert metacognitive control, we expected the subject to show longer latencies (study time) before touching the first item in memory trials than in regular trials. This latency difference was indeed found for trials in which the number of items was 3 or 4, but not when it was 5.