Long-tailed macaques extract statistical information from repeated types of events to make rational decisions under uncertainty

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 different 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 first experienced the probability of rewards associated with different factors separately. In a subsequent test trial, monkeys could then choose between the different 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 findings suggest that the presentation format affects the monkeys’ statistical reasoning abilities.

Is implicit Theory of Mind real but hard to detect? Testing adults with different stimulus materials

Recently, Theory of Mind (ToM) research has been revolutionized by new methods. Eye-tracking studies measuring subjects' looking times or anticipatory looking have suggested that implicit and automatic forms of ToM develop much earlier in ontogeny than traditionally assumed and continue to operate outside of subjects' awareness throughout the lifespan. However, the reliability of these implicit methods has recently been put into question by an increasing number of non-replications. What remains unclear from these accumulating non-replication findings, though, is whether they present true negatives (there is no robust phenomenon of automatic ToM) or false ones (automatic ToM is real but difficult to tap). In order to address these questions, the current study implemented conceptual replications of influential anticipatory looking ToM tasks with a new variation in the stimuli. In two separate preregistered studies, we used increasingly realistic stimuli and controlled for potential confounds. Even with these more realistic stimuli, previous results could not be replicated. Rather, the anticipatory looking pattern found here remained largely compatible with more parsimonious explanations. In conclusion, the reality and robustness of automatic ToM remains controversial.

Why can some implicit Theory of Mind tasks be replicated and others cannot? A test of mentalizing versus submentalizing accounts

In the last 15 years, Theory of Mind research has been revolutionized by the development of new implicit tasks. Such tasks aim at tapping children’s and adults’ uninstructed, largely automatic mental state ascription, indicated in spontaneous looking behavior when observing agents who act on the basis of false beliefs. Studies with anticipatory looking, in particular, have suggested that basic ToM capacities operate from very early in life and remain in unconscious operation throughout the lifespan. Recently, however, systematic replication attempts of anticipatory looking measures have yielded a complex and puzzling mixture of successful, partial and non-replications. The present study aimed at shedding light on the question whether there is a system to this pattern. More specifically, in a set of three preregistered experiments, it was tested whether those conditions that could previously be replicated and those that could not differ in crucial conceptual respects such that the former do not strictly require ToM whereas the latter do. This was tested by the implementation of novel control conditions. The results were complex. There was generally no unambiguous evidence for reliable spontaneous ToM and no effect of the number of passed familiarization trials. Neither was there any unambiguous evidence that the previous mixed patterns of (non-)replications could be explained (away) by the sub-mentalizing account tested in the new control conditions. The empirical situation remains puzzling, and the question whether there is some such thing as implicit and spontaneous ToM remains to be clarified.

Comparative metaphysics: Evolutionary and ontogenetic roots of essentialist thought about objects

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 about objects, in turn, may lay a foundation for psychological essentialism. This article is categorized under: Cognitive Biology > Evolutionary Roots of Cognition Psychology > Comparative Psychology.

Children's understanding of the aspectuality of intentions

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-year-olds, 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.

The Rationality of (Over)imitation

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.

The ontogeny of intent-based normative judgments

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.

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 four experiments, 11 long-tailed 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).

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

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.

Chimpanzees Consider Humans' Psychological States when Drawing Statistical Inferences

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.

The Out-Group Homogeneity Effect Across Development: A Cross-Cultural Investigation

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.

Is Implicit Theory of Mind a Real and Robust Phenomenon? Results From a Systematic Replication Study

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.

Implicit Theory of Mind - An overview of current replications and non-replications

The current dataset contains a qualitative summary of (non-)replication studies of implicit Theory of Mind paradigms. It summarizes for each paradigm, how many replications, partial replications and non-replications were identified and how many of them were published or unpublished. Furthermore, descriptive data and sample sizes are reported. The dataset provides a qualitative overview of the published and unpublished findings in implicit Theory of Mind research.

Implicit Theory of Mind across the life span - Anticipatory looking data

In this work, we present a collection of data from three replication studies of anticipatory looking false belief tasks measuring implicit Theory of Mind. Two paradigms, by Southgate & Senju and Surian & Geraci were replicated in two independent labs. Eye-tracking data was collected and processed in line with the original procedures to allow for an investigation of effects of false belief processing on looking times and first saccades.