Validation of an open source, remote web-based eye-tracking method (WebGazer) for research in early childhood

Measuring eye movements remotely via the participant's webcam promises to be an attractive methodological addition to in-person eye-tracking in the lab. However, there is a lack of systematic research comparing remote web-based eye-tracking with in-lab eye-tracking in young children. We report a multi-lab study that compared these two measures in an anticipatory looking task with toddlers using WebGazer.js and jsPsych. Results of our remotely tested sample of 18-27-month-old toddlers (N = 125) revealed that web-based eye-tracking successfully captured goal-based action predictions, although the proportion of the goal-directed anticipatory looking was lower compared to the in-lab sample (N = 70). As expected, attrition rate was substantially higher in the web-based (42%) than the in-lab sample (10%). Excluding trials based on visual inspection of the match of time-locked gaze coordinates and the participant's webcam video overlayed on the stimuli was an important preprocessing step to reduce noise in the data. We discuss the use of this remote web-based method in comparison with other current methodological innovations. Our study demonstrates that remote web-based eye-tracking can be a useful tool for testing toddlers, facilitating recruitment of larger and more diverse samples; a caveat to consider is the larger drop-out rate.

Infants' biased individuation of in-group members

Adults tend to construe members of their group as "unique individuals" more than members of other groups. This study investigated whether infants exhibit this tendency, even in regard to unfamiliar arbitrary groups. Ninety-six White 1-year-olds were assigned to an Ingroup, Outgroup, or No-Group condition, based on whether or not they shared two preferences (food and shirt color) with women appearing on video sequences. In the critical trial, infants saw two women (Ingroup, Outgroup, or No-Group) - one at a time - appearing from behind a curtain. The curtain opened to reveal only one woman. Infants in the Ingroup condition looked longer at this display than infants in the other two conditions. This suggests that infants in the Ingroup condition had a stronger expectation than those in the other two conditions that there would be two women behind the curtain. In other words, infants individuated in-group members more than out-group members.

Do chimpanzees reason logically?

Psychologists disagree about the development of logical concepts such as or and not. While some theorists argue that infants reason logically, others maintain that logical inference is contingent on linguistic abilities and emerges around age 4. In this Registered Report, we conducted five experiments on logical reasoning in chimpanzees. Subjects (N = 16; 10 females; M = 24 years) participated in the same setup that has been administered to children: the two-, three-, and four-cup-task. Chimpanzees performed above chance in the two-cup-, but not in the three-cup-task. Furthermore, chimpanzees selected the logically correct option more often in the test than the control condition of the four-cup-task. We discuss possible interpretations of these findings and conclude that our results are most consistent with non-deductive accounts.

How robust are egocentric and altercentric interference effects in social cognition? a test with explicit and implicit versions of a continuous false belief task

It has been long assumed that meta-representational theory of mind (ToM) -our ability to ascribe mental states to ourselves and other people- emerges around age four as indicated in performance on explicit verbal false belief tasks. In contrast, newer studies assessing false belief understanding with implicit, non-verbal measures suggest that some form of ToM may be present even in infancy. But these studies now face replication issues, and it remains unclear whether they can provide robust evidence for implicit ToM. One line of research on implicit ToM, however, may remain promising: Studies that tap so-called altercentric biases. Such biases occur when agents in their judgments about the world are influenced (perform slower, more error-prone) in light of another agent's deviating perspective even if that perspective is completely irrelevant to the task; they thus can be seen as indicators of spontaneous and implicit ToM. Altercentric biases are the mirror images of egocentric biases (agents are influenced by their own perspective when evaluating another agent's deviating perspective). In three studies with adults, we aimed to tap both egocentric and altercentric interference effects within the same task format. We used the so-called Sandbox task, a false belief task with continuous locations. In Study 1, we tested an online adaptation of the Sandbox task, which we also used to explore potential cross-cultural differences in these biases. Studies 2 and 3 combined the Sandbox task with mouse-tracking measures. These studies revealed neither egocentric nor altercentric biases. These null results are discussed with regard to the question whether absence of evidence here may present evidence of absence of such spontaneous perspective-taking biases or merely false negatives.

Chimpanzees prepare for alternative possible outcomes

When facing uncertainty, humans often build mental models of alternative outcomes. Considering diverging scenarios allows agents to respond adaptively to different actual worlds by developing contingency plans (covering one's bases). In a pre-registered experiment, we tested whether chimpanzees (Pan troglodytes) prepare for two mutually exclusive possibilities. Chimpanzees could access two pieces of food, but only if they successfully protected them from a human competitor. In one condition, chimpanzees could be certain about which piece of food the human experimenter would attempt to steal. In a second condition, either one of the food rewards was a potential target of the competitor. We found that chimpanzees were significantly more likely to protect both pieces of food in the second relative to the first condition, raising the possibility that chimpanzees represent and prepare effectively for different possible worlds.

Do young children track other's beliefs, or merely their perceptual access? An interactive, anticipatory measure of early theory of mind

This paper aimed to contribute to answering three questions. First, how robust and reliable are early implicit measures of false belief (FB) understanding? Second, do these measures tap FB understanding rather than simpler processes such as tracking the protagonist's perceptual access? Third, do implicit FB tasks tap an earlier, more basic form of theory of mind (ToM) than standard verbal tasks? We conducted a conceptual replication of Garnham & Perner's task (Garnham and Perner 2001 Br. J. Dev. Psychol. 19, 413-432) simultaneously measuring children's anticipatory looking and interactive behaviours toward an agent with a true or FB (N = 81, M = 40 months). Additionally, we implemented an ignorance condition and a standard FB task. We successfully replicated the original findings: children's looking and interactive behaviour differed according to the agent's true or FB. However, children mostly did not differentiate between FB and ignorance conditions in various measures of anticipation and uncertainty, suggesting the use of simpler conceptual strategies than full-blown ToM. Moreover, implicit measures were all related to each other but largely not related to performance in the standard FB task, except for first look in the FB condition. Overall, our findings suggest that these implicit measures are robust but may not tap the same underlying cognitive capacity as explicit FB tasks.

How do children overcome their pragmatic performance problems in the true belief task? The role of advanced pragmatics and higher-order theory of mind

The true belief (TB) control condition of the classical location-change task asks children to ascribe a veridical belief to an agent to predict her action (analog to the false belief (FB) condition to test Theory of Mind (ToM) abilities). Studies that administered TB tasks to a broad age range of children yielded surprising findings of a U-shaped performance curve in this seemingly trivial task. Children before age four perform competently in the TB condition. Children who begin to solve the FB condition at age four, however, fail the TB condition and only from around age 10, children succeed again. New evidence suggests that the decline in performance around age four reflects pragmatic confusions caused by the triviality of the task rather than real competence deficits in ToM. Based on these results, it can be hypothesized that the recovery of performance at the end of the U-shaped curve reflects underlying developments in children's growing pragmatic awareness. The aim of the current set of studies, therefore, was to test whether the developmental change at the end of the U-shaped performance curve can be explained by changes in children's pragmatic understanding and by more general underlying developmental changes in recursive ToM or recursive thinking in general. Results from Study 1 (N = 81, 6-10 years) suggest that children's recursive ToM, but not their advanced pragmatic understanding or general recursive thinking abilities predict their TB performance. However, this relationship could not be replicated in Study 2 (N = 87, 6-10 years) and Study 3 (N = 64, 6-10 years) in which neither recursive ToM nor advanced pragmatic understanding or recursive thinking explained children's performance in the TB task. The studies therefore remain inconclusive regarding explanations for the end of the U-shaped performance curve. Future research needs to investigate potential pragmatic and general cognitive foundations of this developmental change more thoroughly.

Chimpanzees consider freedom of choice in their evaluation of social action

Judgements of wrongdoing in humans often hinge upon an assessment of whether a perpetrator acted out of free choice: whether they had more than one option. The classic inhibitors of free choice are constraint (e.g. having your hands tied together) and ignorance (e.g. being unaware that an alternative exists). Here, across two studies, we investigate whether chimpanzees consider these factors in their evaluation of social action. Chimpanzees interacted with a human experimenter who handed them a non-preferred item of food, either because they were physically constrained from accessing the preferred item (Experiment 1) or because they were ignorant of the availability of the preferred item (Experiment 2). We found that chimpanzees were more likely to accept the non-preferred food and showed fewer negative emotional responses when the experimenter was physically constrained compared with when they had free choice. We did not, however, find an effect of ignorance on chimpanzee's evaluation. Freedom of choice factors into chimpanzees' evaluation of how they are treated, but it is unclear whether mental state reasoning is involved in this assessment.

Why Do Children Who Solve False Belief Tasks Begin to Find True Belief Control Tasks Difficult? A Test of Pragmatic Performance Factors in Theory of Mind Tasks

The litmus test for the development of a metarepresentational Theory of Mind is the false belief (FB) task in which children have to represent how another agent misrepresents the world. Children typically start mastering this task around age four. Recently, however, a puzzling finding has emerged: Once children master the FB task, they begin to fail true belief (TB) control tasks. Pragmatic accounts assume that the TB task is pragmatically confusing because it poses a trivial academic test question about a rational agent's perspective; and we do not normally engage in such discourse about subjective mental perspectives unless there is at least the possibility of error or deviance. The lack of such an obvious possibility in the TB task implicates that there might be some hidden perspective difference and thus makes the task confusing. In the present study, we test the pragmatic account by administering to 3- to 6-year-olds (N = 88) TB and FB tasks and structurally analogous true and false sign (TS/FS) tasks. The belief and sign tasks are matched in terms of representational and metarepresentational complexity; the crucial difference is that TS tasks do not implicate an alternative non-mental perspective and should thus be less pragmatically confusing than TB tasks. The results show parallel and correlated development in FB and FS tasks, replicate the puzzling performance pattern in TB tasks, but show no trace of this in TS tasks. Taken together, these results speak in favor of the pragmatic performance account.

Online Testing Yields the Same Results as Lab Testing: A Validation Study With the False Belief Task

Recently, online testing has become an increasingly important instrument in developmental research, in particular since the COVID-19 pandemic made in-lab testing impossible. However, online testing comes with two substantial challenges. First, it is unclear how valid results of online studies really are. Second, implementing online studies can be costly and/or require profound coding skills. This article addresses the validity of an online testing approach that is low-cost and easy to implement: The experimenter shares test materials such as videos or presentations via video chat and interactively moderates the test session. To validate this approach, we compared children’s performance on a well-established task, the change-of-location false belief task, in an in-lab and online test setting. In two studies, 3- and 4-year-old received online implementations of the false belief version (Study 1) and the false and true belief version of the task (Study 2). Children’s performance in these online studies was compared to data of matching tasks collected in the context of in-lab studies. Results revealed that the typical developmental pattern of performance in these tasks found in in-lab studies could be replicated with the novel online test procedure. These results suggest that the proposed method, which is both low-cost and easy to implement, provides a valid alternative to classical in-person test settings.

Chimpanzees consider alternative possibilities

Humans reason not only about actual events (what is), but also about possible events (what could be). Many key operations of human cognition involve the representation of possibilities, including moral judgment, future planning, and causal understanding¹. But little is known about the evolutionary roots of this kind of thought. Humans' closest relatives, chimpanzees, possess several cognitive abilities that are closely related to reasoning about alternatives: they plan for the future², evaluate other's actions³, and reason causally⁴. However, in the first direct test of the ability to consider alternatives, Redshaw and Suddendorf⁵ claim that chimpanzees are not able to represent alternative possibilities. Here, using a novel method, we challenge this conclusion: our results suggest that, like human cognition, chimpanzee thought is not limited to what is, but also involves reasoning about what could be the case.

Dogs distinguish human intentional and unintentional action

When dogs interact with humans, they often show appropriate reactions to human intentional action. But it is unclear from these everyday observations whether the dogs simply respond to the action outcomes or whether they are able to discriminate between different categories of actions. Are dogs able to distinguish intentional human actions from unintentional ones, even when the action outcomes are the same? We tested dogs' ability to discriminate these action categories by adapting the so-called "Unwilling vs. Unable" paradigm. This paradigm compares subjects' reactions to intentional and unintentional human behaviour. All dogs received three conditions: In the unwilling-condition, an experimenter intentionally withheld a reward from them. In the two unable-conditions, she unintentionally withheld the reward, either because she was clumsy or because she was physically prevented from giving the reward to the dog. Dogs clearly distinguished in their spontaneous behaviour between unwilling- and unable-conditions. This indicates that dogs indeed distinguish intentional actions from unintentional behaviour. We critically discuss our findings with regard to dogs' understanding of human intentional action.

Children understand subjective (undesirable) desires before they understand subjective (false) beliefs

Our folk psychology is built around the ascription of beliefs (and related cognitive states) and desires (and related conative states). How and when children develop a concept of these different kinds of propositional attitudes has been the subject of a long-standing debate. Asymmetry accounts assume that children develop a conception of desires earlier than they develop a concept of beliefs. In contrast, the symmetry account assumes that conceptions of both kinds of attitudes are based on the same underlying capacity to ascribe subjective perspectives. Accordingly, a genuine subjective understanding of desires develops in tandem with subjective belief understanding. So far, existing evidence that tested these two accounts remains inconclusive, with inconsistent findings resulting from diverging methods. Therefore, the current study tested between the two accounts in a more systematic way. First, we used a particularly clear test case-value-incompatible (wicked) desires. Such desires are strongly subjective because they are desirable only from the agent's perspective but not from an objective perspective. Second, we probed children's ascription of such desires in the most direct and simplified ways. Third, we directly compared children's desire understanding with their ascription of subjective beliefs. Results revealed that young children were better in reasoning about subjective desires than about subjective beliefs. Desire reasoning was not correlated with subjective belief reasoning, and children did not have more difficulties in reasoning about strongly subjective wicked desires than about neutral desires. All in all, these findings are not in line with the predictions of the symmetry account but speak in favor of the asymmetry account.

The Ape Lottery: Chimpanzees Fail To Consider Spatial Information When Drawing Statistical Inferences

Humans and nonhuman great apes share a sense for intuitive statistics, making intuitive probability judgments based on proportional information. This ability is of tremendous importance, in particular for predicting the outcome of events using prior information and for inferring general regularities from limited numbers of observations. Already in infancy, humans functionally integrate intuitive statistics with other cognitive domains, rendering this type of reasoning a powerful tool to make rational decisions in a variety of contexts. Recent research suggests that chimpanzees are capable of one type of such cross-domain integration: The integration of statistical and social information. Here, we investigated whether apes can also integrate physical information into their statistical inferences. We tested 14 sanctuary-living chimpanzees in a new task setup consisting of two “gumball machine”-apparatuses that were filled with different combinations of preferred and non-preferred food items. In four test conditions, subjects decided which of two apparatuses they wanted to operate to receive a random sample, while we varied both the proportional composition of the food items as well as their spatial configuration above and below a barrier. To receive the more favorable sample, apes needed to integrate proportional and spatial information. Chimpanzees succeeded in conditions in which we provided them either with proportional information or spatial information, but they failed to correctly integrate both types of information when they were in conflict. Whether these limitations in chimpanzees' performance reflect true limits of cognitive competence or merely performance limitations due to accessory task demands is still an open question.

Actions do not speak louder than words in an interactive false belief task

Traditionally, it had been assumed that meta-representational Theory of Mind (ToM) emerges around the age of 4 when children come to master standard false belief (FB) tasks. More recent research with various implicit measures, though, has documented much earlier competence and thus challenged the traditional picture. In interactive FB tasks, for instance, infants have been shown to track an interlocutor's false or true belief when interpreting her ambiguous communicative acts (Southgate et al. 2010 Dev. Sci. 13, 907-912. (doi:10.1111/j.1467-7687.2009.00946.x)). However, several replication attempts so far have produced mixed findings (e.g. Dörrenberg et al. 2018 Cogn. Dev. 46, 12-30. (doi:10.1016/j.cogdev.2018.01.001); Grosse Wiesmann et al. 2017 Dev. Sci. 20, e12445. (doi:10.1111/desc.12445); Király et al. 2018 Proc. Natl Acad. Sci. USA 115, 11 477-11 482. (doi:10.1073/pnas.1803505115)). Therefore, we conducted a systematic replication study, across two laboratories, of an influential interactive FB task (the so-called 'Sefo' tasks by Southgate et al. 2010 Dev. Sci. 13, 907-912. (doi:10.1111/j.1467-7687.2009.00946.x)). First, we implemented close direct replications with the original age group (17-month-olds) and compared their performance to those of 3-year-olds. Second, we designed conceptual replications with modifications and improvements regarding pragmatic ambiguities for 2-year-olds. Third, we validated the task with explicit verbal test versions in older children and adults. Results revealed the following: the original results could not be replicated, and there was no evidence for FB understanding measured by the Sefo task in any age group except for adults. Comparisons to explicit FB tasks suggest that the Sefo task may not be a sensitive measure of FB understanding in children and even underestimate their ToM abilities. The findings add to the growing replication crisis in implicit ToM research and highlight the challenge of developing sensitive, reliable and valid measures of early implicit social cognition.

Do infants and preschoolers quantify probabilities based on proportions?

Most statistical problems encountered throughout life require the ability to quantify probabilities based on proportions. Recent findings on the early ontogeny of this ability have been mixed: For example, when presented with jars containing preferred and less preferred items, 12-month-olds, but not 3- and 4-years-olds, seem to rely on the proportions of objects in the jars to predict the content of samples randomly drawn out of them. Given these contrasting findings, it remains unclear what the probabilistic reasoning abilities of young children are and how they develop. In our study, we addressed this question and tested, with identical methods across age groups and similar methods to previous studies, whether 12-month-olds and 3- and 4-years-olds rely on proportions of objects to estimate probabilities of random sampling events. Results revealed that neither infants nor preschoolers do. While preschoolers' performance is in line with previous findings, infants' performance is difficult to interpret given their failure in a control condition in which the outcomes happened with certainty rather than a graded probability. More systematic studies are needed to explain why infants succeeded in a previous study but failed in our study.