When maths trumps logic: probabilistic judgements in chimpanzees

Hanuš, Daniel; Call, Josep

doi:10.1098/rsbl.2014.0892

Cited by 28 publications

(36 citation statements)

References 17 publications

(16 reference statements)

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“…The monkeys learned to choose those arrays with the greater ratio of positive to negative stimuli and were able to generalize to novel ratios. Similarly, as in the previously mentioned study with chimpanzees (Hanus & Call, ), the performance was directly influenced by the magnitude of difference between the two ratios to be discriminated. Interestingly, just as human infants (McCrink & Wynn, ), the two macaques tested were able to discriminate a ROR of 2, which is much lower than those used in our experiments.…”

Section: Discussionsupporting

confidence: 58%

“…Recent research suggests that indeed the magnitude of difference between two proportions is crucial for non‐human primates to discriminate probabilities. Hanus & Call () presented chimpanzees with two trays, each of them with a different ratio of hidden food items to potential hiding locations and therefore a different likelihood of finding food. This study revealed that subjects’ performance was influenced by the relative difference between the two probabilities as soon as a certain threshold thereof was reached.…”

Section: Discussionmentioning

confidence: 99%

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Are great apes able to reason from multi‐item samples to populations of food items?

Eckert

Rakoczy

Call

2017

American J Primatol

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Inductive learning from limited observations is a cognitive capacity of fundamental importance. In humans, it is underwritten by our intuitive statistics, the ability to draw systematic inferences from populations to randomly drawn samples and vice versa. According to recent research in cognitive development, human intuitive statistics develops early in infancy. Recent work in comparative psychology has produced first evidence for analogous cognitive capacities in great apes who flexibly drew inferences from populations to samples. In the present study, we investigated whether great apes (Pongo abelii, Pan troglodytes, Pan paniscus, Gorilla gorilla) also draw inductive inferences in the opposite direction, from samples to populations. In two experiments, apes saw an experimenter randomly drawing one multi-item sample from each of two populations of food items. The populations differed in their proportion of preferred to neutral items (24:6 vs. 6:24) but apes saw only the distribution of food items in the samples that reflected the distribution of the respective populations (e.g., 4:1 vs. 1:4). Based on this observation they were then allowed to choose between the two populations. Results show that apes seemed to make inferences from samples to populations and thus chose the population from which the more favorable (4:1) sample was drawn in Experiment 1. In this experiment, the more attractive sample not only contained proportionally but also absolutely more preferred food items than the less attractive sample. Experiment 2, however, revealed that when absolute and relative frequencies were disentangled, apes performed at chance level. Whether these limitations in apes' performance reflect true limits of cognitive competence or merely performance limitations due to accessory task demands is still an open question.

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Section: Discussionsupporting

confidence: 58%

Section: Discussionmentioning

confidence: 99%

Are great apes able to reason from multi‐item samples to populations of food items?

Eckert

Rakoczy

Call

2017

American J Primatol

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“…Alternatively, the present findings may reflect true competence limitations and show that macaques are incapable of using intuitive statistics (although they might still be able to engage in statistical reasoning using other formats of information, such as frequencies of sequential events for example, an ability highlighted in chimpanzees 24 ). While the present findings cannot rule out their lack of competence, one piece of evidence seems to speak against it: Maja (and Sally to a lesser extent) performed well in most conditions.…”

Section: Discussionmentioning

confidence: 78%

“…Recently, similar reasoning abilities were highlighted in nonhuman primates: four species of apes 22 , and one species of capuchins 23 were able to use populations of food items to form expectations about sampling events, based on a paradigm originally developed for children 15 . Another study showed that chimpanzees used proportional information to infer which of two trays containing different food/cup ratios was more likely to yield a cup containing food 24 . These studies are interesting in two aspects.…”

Section: Introductionmentioning

confidence: 99%

Do long-tailed macaques engage in intuitive statistics?

Placì

Eckert

Rakoczy

et al. 2018

Preprint

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Phone +49 551 3851-0 2 Human infants, apes and capuchins have been found to engage in intuitive statistics, generating predictions from populations to samples based on proportional information. This suggests that statistical reasoning might depend on some core knowledge that is shared with other species. Here, we investigated whether such intuitive statistical reasoning is also present in a species of Old World monkeys, to aid in the reconstruction of the evolution of this capacity. In a series of 7 test conditions, 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 monkey to choose. Results revealed that at least one individual seemed to make systematic population-to-sample inferences and consistently chose the sample from the population with the more favorable distribution of preferred vs. neutral food items. While it is not clear whether she used relative or absolute quantities of food, she seemed to understand the difference between a correct choice and a favorable draw and thus some basic principles of intuitive statistics.3

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“…One recent study did find some such evidence for an involvement of the analogue magnitude system in decision making under uncertainty in nonhuman great apes: Hanus and Call (2014) gave chimpanzees the choice between two trays on which food items were hidden under cups. The trays differed with respect to the ratio of food items to cups and thus in chances of finding food.…”

Section: Mccrink and Wynnmentioning

confidence: 99%

Intuitive statistical inferences in chimpanzees and humans follow Weber’s law

et al. 2018

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Humans and nonhuman great apes share a sense for intuitive statistical reasoning, making intuitive probability judgments based on proportional information. This ability is of fundamental importance, in particular for inferring general regularities from finite numbers of observations and, vice versa, for predicting the outcome of single events using prior information. To date it remains unclear which cognitive mechanism underlies and enables this capacity. The aim of the present study was to gain deeper insights into the cognitive structure of intuitive statistics by probing its signatures in chimpanzees and humans. We tested 24 sanctuary-living chimpanzees in a previously established paradigm which required them to reason from populations of food items with different ratios of preferred (peanuts) and non-preferred items (carrot pieces) to randomly drawn samples. In a series of eight test conditions, the ratio between the two ratios to be discriminated (ROR) was systematically varied ranging from 1 (same proportions in both populations) to 16 (high magnitude of difference between populations). One hundred and forty-four human adults were tested in a computerized version of the same task. The main result was that both chimpanzee and human performance varied as a function of the log(ROR) and thus followed Weber's law. This suggests that intuitive statistical reasoning relies on the same cognitive mechanism that is used for comparing absolute quantities, namely the analogue magnitude system.

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When maths trumps logic: probabilistic judgements in chimpanzees

Cited by 28 publications

References 17 publications

Are great apes able to reason from multi‐item samples to populations of food items?

Are great apes able to reason from multi‐item samples to populations of food items?

Do long-tailed macaques engage in intuitive statistics?

Intuitive statistical inferences in chimpanzees and humans follow Weber’s law

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