Data from: Long-tailed macaques (Macaca fascicularis) can use simple heuristics but fail at drawing statistical inferences from populations to samples

Human infants, apes, and capuchin monkeys engage in intuitive statistics: they generate predictions from populations of objects to samples based on proportional information. This suggests that statistical reasoning might depend on some core knowledge that humans share with other primate species. To aid the reconstruction of the evolution of this capacity, we investigated whether intuitive statistical reasoning is also present in a species of Old World monkey. In a series of 4 experiments, 11 long-tailed macaques were offered different pairs of populations containing varying proportions of preferred vs. neutral food items. One population always contained a higher proportion of preferred items than the other. An experimenter simultaneously drew one item out of each population, hid them in her fists and presented them to the monkeys to choose. Although some individuals performed well across most experiments, our results imply that long-tailed macaques as a group did not make statistical inferences from populations of food items to samples but rather relied on heuristics. These findings suggest that there may have been convergent evolution of this ability in New World monkeys and apes (including humans).RawDataThis is the excel file used during data collection and for the data analyses. For each step and each experiment of the study, it provides information about the day of testing, the name of the subjects tested, the session and trial number, the side on which each population was presented, and the choice of the monkeys.IndividualScoresCSV file containing the data to calculate means, SD, effect sizes and used for the t.test, the binomial tests, and Fig. 2.EffectHandsCSV file used for the analyses to check the effect of the state of the arms on monkeys' choices.TTest_BinomialTest_BoxPlot_PlacìR code used to calculate means, SD, effect sizes, t-tests, binomial tests and plot Fig. 2.EffectHands_PlacìR code to test the effect of the state of the arms on monkeys' choices.LearningCurves_PlacìR code to test whether monkeys learnt to associate a proportion to a favourable sample across trials and to plot Fig. S1 of the supplementary material