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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
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Recent work on the side-effect effect has shown that subjects' intentionality judgments are influenced by moral evaluations. In six experiments, we tested four different candidates for the cognitive foundation derived from prominent explanatory accounts (prescriptiveness, [un-] expectedness, blame and a shift in default attitudes) against each other in three steps. First, Study 1 showed that the effect even extends to certain descriptive norms. Second, Studies 2–5 investigated the candidates more directly. Results reveal that intentionality judgments could best be explained by underlying shifts in default attitudes. Third, Study 6 experimentally manipulated this default attitude, leading to the predicted change in intentionality judgments.
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When evaluating norm transgressions, children begin to show some sensitivity to the agent’s intentionality around preschool age. However, the specific developmental trajectories of different forms of such intent-based judgments and their cognitive underpinnings are still largely unclear. The current studies, therefore, systematically investigated the development of intent-based normative judgments as a function of two crucial factors: (a) the type of the agent’s mental state underlying a normative transgression, and (b) the type of norm transgressed (moral versus conventional). In Study 1, 5- and 7-year-old children as well as adults were presented with vignettes in which an agent transgressed either a moral or a conventional norm. Crucially, she did so either intentionally, accidentally (not intentionally at all) or unknowingly (intentionally, yet based on a false belief regarding the outcome). The results revealed two asymmetries in children’s intent-based judgments. First, all age groups showed greater sensitivity to mental state information for moral compared to conventional transgressions. Second, children’s (but not adults’) normative judgments were more sensitive to the agent’s intention than to her belief. Two subsequent studies investigated this asymmetry in children more closely and found evidence that it is based on performance factors: children are able in principle to take into account an agent’s false belief in much the same way as her intentions, yet do not make belief-based judgments in many existing tasks (like that of Study 1) due to their inferential complexity. Taken together, these findings contribute to a more systematic understanding of the development of intent-based normative judgment.
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When children come to grasp the concept of intention is a central question in theory of mind research. Existing studies, however, present a puzzling picture. On the one hand, infants distinguish between intentional and accidental actions. On the other hand, previous work suggests that until 8 years of age children do not yet understand an essential property of intentions—their aspectuality. Intentions are aspectual in the sense that they refer to objects and actions only under specific aspects. For example, Oedipus married Jocasta without knowing that she was his mother. Thus, he intentionally married Jocasta but did not intentionally marry his mother. However, the negative findings from these studies may indicate performance limitations rather than competence limitations. The rationale of the current set of studies, therefore, was to test children’s understanding of the aspectuality of intentions in a simplified, cognitively less demanding design. The participants, 5- and 6-year-olds (Study 1) and 4-year-olds (Study 2), were involved in simple games where they (or another agent) intentionally acted on objects that had an obvious first identity and a hidden second identity. Children either did or did not know about the toy’s second identity at the moment of acting. After their actions, children were asked about their intentions regarding the toys’ different identities. Results revealed that the 5- and 6-year-olds, but not the 4-yearolds, systematically considered how they (or another agent) represented the objects when making intentionality judgments. Thus, an understanding of aspectual intentions seems to develop at around the late preschool years—much earlier than previously assumed.
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Human children and apes seem to be intuitive statisticians when making predictions from populations of objects to randomly drawn samples, whereas monkeys seem not to be. Statistical reasoning can also be investigated in tasks in which the probabilities of diferent possibilities must be inferred from relative frequencies of events, but little is known about the performance of nonhuman primates in such tasks. In the current study, we investigated whether long-tailed macaques extract statistical information from repeated types of events to make predictions under uncertainty. In each experiment, monkeys frst experienced the probability of rewards associated with diferent factors separately. In a subsequent test trial, monkeys could then choose between the diferent factors presented simultaneously. In Experiment 1, we tested whether long-tailed macaques relied on probabilities and not on a comparison of absolute quantities to make predictions. In Experiment 2 and 3 we varied the nature of the predictive factors and the complexity of the covariation structure between rewards and factors. Results indicate that long-tailed macaques extract statistical information from repeated types of events to make predictions and rational decisions under uncertainty, in more or less complex scenarios. These fndings suggest that the presentation format afects the monkeys’ statistical reasoning abilities.
