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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 four experiments, 11 longtailed macaques were offered different pairs of populations containing varying proportions of preferred versus 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).
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Three studies tested scope and limits of children’s implicit and explicit theory of mind. In Studies 1 and 2, threeto six-year-olds (N = 84) were presented with closely matched explicit false belief tasks that differed in whether or not they required an understanding of aspectuality. Results revealed that children performed equally well in the different tasks, and performance was strongly correlated. Study 3 tested two-year-olds (N = 81) in implicit interactive versions of these tasks and found evidence for dis-unity: children performed competently only in those tasks that did not require an understanding of aspectuality. Taken together, the present findings suggest that early implicit and later explicit theory of mind tasks may tap different forms of cognitive capacities.
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Recently, theory-of-mind research has been revolutionized by findings from novel implicit tasks suggesting that at least some aspects of false-belief reasoning develop earlier in ontogeny than previously assumed and operate automatically throughout adulthood. Although these findings are the empirical basis for far-reaching theories, systematic replications are still missing. This article reports a preregistered large-scale attempt to replicate four influential anticipatory-looking implicit theory-of-mind tasks using original stimuli and procedures. Results showed that only one of the four paradigms was reliably replicated. A second set of studies revealed, further, that this one paradigm was no longer replicated once confounds were removed, which calls its validity into question. There were also no correlations between paradigms, and thus, no evidence for their convergent validity. In conclusion, findings from anticipatory-looking false-belief paradigms seem less reliable and valid than previously assumed, thus limiting the conclusions that can be drawn from them.
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Recent findings from new implicit looking time tasks indicate that children show anticipatory looking patterns suggesting false belief processing from very early on; however, systematic and independent tests of their replicability and their convergent validity are still outstanding. The current paper reports three studies from two independent research labs that attempted to test the replicability and convergent validity (using correlation analyses) of the Southgate et al. (2007) and the Surian and Geraci (2012) paradigms. Results showed that the original findings can neither be replicated in children nor in elderly adults, and can only partially be replicated in adults. Furthermore, the two different paradigms did not correlate, which puts into question the convergent validity of these tasks as tapping the same capacity of an implicit Theory of Mind. In conclusion, the present studies suggest that the results from implicit Theory of Mind tasks should be treated with caution.
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Imitation is a powerful and ubiquitous social learning strategy, fundamental for the development of individual skills and cultural traditions. Recent research on the cognitive foundations and development of imitation, though, presents a surprising picture: Although even infants imitate in selective, efficient, and rational ways, children and adults engage in overimitation. Rather than imitating selectively and efficiently, they sometimes faithfully reproduce causally irrelevant actions as much as relevant ones. In this article, we suggest a new perspective on this phenomenon by integrating established findings on children’s more general capacities for rational action parsing with newer findings on overimitation. We suggest that overimitation is a consequence of children’s growing capacities to understand causal and social constraints in relation to goals and that it rests on the human capacity to represent observed actions simultaneously on different levels of goal hierarchies.
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—Young children learn selectively from reliable rather than unreliable models. Yet the question of what cognitive processes this early selectivity builds on remains unanswered. One line of research suggests that rational trait reasoning might be the basis of young children’s selective trust, while others suggest less sophisticated processes. In this article, we provide an overview of the development of selective trust and introduce a new theoretical framework to explain the seemingly divergent findings. Young children’s selective trust can best be explained by assuming two kinds of underlying cognitive processes: one fast, implicit, and heuristic process that provides default judgments, and one systematic, slow, and effortful process that intervenes under specific circumstances. We discuss findings in light of this framework and propose testable predictions for research.
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Recent research has amply documented that even preschoolers learn selectively from others, preferring, for example, reliable over unreliable and competent over incompetent models. It remains unclear, however, what the cognitive foundations of such selective learning are, in particular, whether it builds on rational inferences or on less sophisticated processes. The current study, therefore, was designed to test directly the possibility that children are in principle capable of selective learning based on rational inference, yet revert to simpler strategies such as global impression formation under certain circumstances. Preschoolers (N = 75) were shown pairs of models that either differed in their degree of competence within one domain (strong vs. weak or knowledgeable vs. ignorant) or were both highly competent, but in different domains (e.g., strong vs. knowledgeable model). In the test trials, children chose between the models for strength- or knowledge-related tasks. The results suggest that, in fact, children are capable of rational inference-based selective trust: when both models were highly competent, children preferred the model with the competence most predictive and relevant for a given task. However, when choosing between two models that differed in competence on one dimension, children reverted to halo-style wide generalizations and preferred the competent models for both relevant and irrelevant tasks. These findings suggest that the rational strategies for selective learning, that children master in principle, can get masked by various performance factors.
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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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Great apes have been shown to be intuitive statisticians: they can use proportional information within a population to make intuitive probability judgments about randomly drawn samples [1, J.E., J.C., J.H., E.H., and H.R., unpublished data]. Humans, from early infancy onward, functionally integrate intuitive statistics with other cognitive domains to judge the randomness of an event [2–6]. To date, nothing is known about such cross-domain integration in any nonhuman animal, leaving uncertainty about the origins of human statistical abilities. We investigated whether chimpanzees take into account information about psychological states of experimenters (their biases and visual access) when drawing statistical inferences. We tested 21 sanctuary-living chimpanzees in a previously established paradigm that required subjects to infer which of two mixed populations of preferred and non-preferred food items was more likely to lead to a desired outcome for the subject. In a series of three experiments, we found that chimpanzees chose based on proportional information alone when they had no information about experimenters’ preferences and (to a lesser extent) when experimenters had biases for certain food types but drew blindly. By contrast, when biased experimenters had visual access, subjects ignored statistical information and instead chose based on experimenters’ biases. Lastly, chimpanzees intuitively used a violation of statistical likelihoods as indication for biased sampling. Our results suggest that chimpanzees have a random sampling assumption that can be overridden under the appropriate circumstances and that they are able to use mental state information to judge whether this is necessary. This provides further evidence for a shared statistical inference mechanism in apes and humans.
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A growing body of infant studies with various implicit, non-verbal measures has suggested that Theory of Mind (ToM) may emerge much earlier than previously assumed. While explicit verbal ToM findings are highly replicable and show convergent validity, systematic replication studies of infant ToM, as well as convergent validations of these measures, are still missing. Here, we report a systematic study of the replicability and convergent validity of implicit ToM tasks using four different measures with 24-month-olds (N = 66): Anticipatory looking, looking times and pupil dilation in violation-of-expectation paradigms, and spontaneous communicative interaction. Results of anticipatory looking and interaction-based tasks did not replicate previous findings, suggesting that these tasks do not reliably measure ToM. Looking time and new pupil dilation measures revealed sensitivity to belief-incongruent outcomes which interacted with the presentation order of outcomes, indicating limited evidence for implicit ToM processes under certain conditions. There were no systematic correlations of false belief processing between the tasks, thus failing to provide convergent validity. The present results suggest that the robustness and validity of existing implicit ToM tasks needs to be treated with more caution than previously practiced, and that not all non-verbal tasks and measures are equally suited to tap into implicit ToM processing.
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The present studies investigated the out-group homogeneity effect in 5- and 8-year-old Israeli and German children (n = 150) and adults (n = 96). Participants were asked to infer whether a given property (either biological or psychological) was true of an entire group—either the participants’ in-group (“Jews” or “Germans”) or their out-group (“Arabs” or “Turks”). To that end, participants had to select either a homogenous or a heterogeneous sample of group members. It was found that across ages and countries, participants selected heterogeneous samples less often when inferring the biological properties of out-compared to in-group members. No effect was found regarding psychological properties. These findings have important implications for our understanding of the origins of intergroup bias.
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At around their third birthday, children begin to enforce social norms on others impersonally, often using generic normative language, but little is known about the developmental building blocks of this abstract norm understanding. Here, we investigate whether even toddlers show signs of enforcing on others interpersonally how “we” do things. In an initial dyad, 18-month-old infants learnt a simple game-like action from an adult. In two experiments, the adult either engaged infants in a normative interactive activity (stressing that this is the way “we” do it) or, as a non-normative control, marked the same action as idiosyncratic, based on individual preference. In a test dyad, infants had the opportunity to spontaneously intervene when a puppet partner performed an alternative action. Infants intervened, corrected, and directed the puppet more in the normative than in the non-normative conditions. These findings suggest that, during the second year of life, infants develop second-personal normative expectations about their partner’s behavior (“You should do X!”) in social interactions, thus making an important step toward understanding the normative structure of human cultural activities. These simple normative expectations will later be scaled up to group-minded and abstract social norms.
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How do animals and young children see the world around them in its most basic structure, and how do such world-views develop over time? These are questions of what could be called comparative and developmental metaphysics. The present paper gives an introduction to this newly emerging field of research. Special emphasis is put on thinking about the world as made up of discrete and enduring objects as the most fundamental form of objective thought. The paper discusses whether language is necessary for such basic forms of objective thought, and whether thinking
