Do infants understand false beliefs? We don’t know yet – A commentary on Baillargeon, Buttelmann and Southgate’s commentary

Altercentric bias in preverbal infants' encoding of object kind

Human infants may exhibit an altercentric bias, where the perspective of others biases their own cognition. This bias may serve a crucial learning function in early ontogeny. This work tested the two main predictions of an altercentric bias in 14-month-old infants: (i) conceptual information should also be encoded altercentrically, and (ii) the other's perspective may completely override infants' own processing. We probed if infants detect a semantic mismatch if hidden objects are labelled incorrectly from their own, or another person's perspective. Experiment 1 found a reduced electrophysiological mismatch response (the 'N400' event-related potential) when labeling was congruent from the other's perspective compared to incongruent, though it was always incongruent for the infant. Experiment 2 found no effect of (in)congruency from the infants' perspective when labeling was always congruent from the other's. These findings demonstrate a strong altercentric bias that prioritizes encoding conceptual information from others' perspective during early development.

Evidence that altercentric biases in a continuous false belief task depend on highlighting the agent's belief

As social beings, we excel at understanding what other people think or believe. We even seem to be influenced by the belief of others in situations where it is irrelevant to our current tasks. Such altercentric interference has been proposed to reflect implicit belief processing. However, in which situations altercentric interference occurs and to what extent it is automatic or dependent on the relevance of the belief in context are open questions. To investigate this, we developed a novel task testing whether participants show an altercentric bias when searching for an object in a continuous search space (a 'sandbox'). Critically, another agent is present that holds either a true or a false belief about the object location, depending on condition. We predicted that participants' search for the object would deviate from its actual location in direction of where the agent believed the object to be. Further, we tested how this altercentric bias would interact with an explicit belief reasoning version of the task, where participants are asked where the agent would look for the object. In two large, preregistered studies (N = 113 and N = 157), we found evidence for an altercentric bias in participants' object search. Importantly, this bias was only present in participants who conducted the explicit before the implicit task and started the experiment with the false belief condition. These findings indicate that altercentric biases depend on the relevance of the other's belief in the context of the task, suggesting that spontaneous belief processing is not automatic but context dependent.

Coregistration of EEG and eye-tracking in infants and developing populations

Infants cannot be instructed where to look; therefore, infant researchers rely on observation of their participant's gaze to make inferences about their cognitive processes. They therefore started studying infant attention in the real world from early on. Developmental researchers were early adopters of methods combining observations of gaze and behaviour with electroencephalography (EEG) to study attention and other cognitive functions. However, the direct combination of eye-tracking methods and EEG to test infants is still rare, as it includes specific challenges. The current article reviews the development of co-registration research in infancy. It points out specific challenges of co-registration in infant research and suggests ways to overcome them. It ends with recommendations for implementing the co-registration of EEG and eye-tracking in infant research to maximise the benefits of the two measures and their combination and to orient on Open Science principles while doing so. In summary, this work shows that the co-registration of EEG and eye-tracking in infant research can be beneficial to studying natural and real-world behaviour despite its challenges.

Three- but not 2-year-olds misinform others spontaneously in an interaction-based task

One-year-olds spontaneously inform others, but less is known about the emergence of spontaneous misinforming. The current study investigated whether young children who spontaneously inform ignorant others also deliberately misinform others in matched uninstructed interactions. Conceptually, misinforming provides a convincing case for interaction-based, implicit false belief understanding. In a simplified, anticipatory and interactive paradigm, a protagonist puppet played with the child and an object and then hid the object in one of two boxes. When the protagonist was temporarily absent, either her friend or a competitor puppet searched for the hidden object. Children spontaneously joined the play and helped or hindered by informing or misinforming the puppets. Experiment 1 revealed that 2-year-olds spontaneously informed the friend. However, they did not selectively misinform the competitor. In order to exclude methodological biases and replicate previous findings, Experiment 2 tested 3-year-olds, confirming skills for spontaneous misinforming with the same paradigm. Findings reveal that informing, but not misinforming, is part of younger children's early spontaneous communication, which suggests a conceptual distinction in the use of communication and casts doubts on an interactive use of false belief understanding in early interactions.

The COVID-19 pandemic and social cognitive outcomes in early childhood

The COVID-19 pandemic and ensuing lockdowns led to sweeping changes in the everyday lives of children and families, including school closures, remote work and learning, and social distancing. To date no study has examined whether these profound changes in young children's day to day social interactions impacted the development of social cognition skills in early childhood. To address this question, we compared the performance of two cohorts of 3.5- to 5.5-year-old children tested before and after the COVID-19 lockdowns on several measures of false-belief understanding, a critical social cognition skill that undergoes important developments in this age range. Controlling for age and language skills, children tested after the pandemic demonstrated significantly worse false-belief understanding than those tested before the pandemic, and this difference was larger for children from lower socioeconomic status (SES) backgrounds. These results suggest that the pandemic negatively impacted the development of social cognition skills in early childhood, especially for lower SES children.

Do autistic adults spontaneously reason about belief? A detailed exploration of alternative explanations

Southgate et al.'s (Southgate 2007 Psychol. Sci. 18, 587-92 (doi:10.1111/j.1467-9280.2007.01944.x)) anticipatory-looking paradigm has presented exciting yet inconclusive evidence surrounding spontaneous mentalizing in autism. The present study aimed to develop this paradigm to address alternative explanations for the lack of predictive eye movements on false-belief tasks by autistic adults. This was achieved through implementing a multi-trial design with matched true-belief conditions, and both high and low inhibitory demand false-belief conditions. We also sought to inspect if any group differences were related to group-specific patterns of attention on key events. Autistic adults were compared with non-autistic adults on this adapted implicit mentalizing task and an established explicit task. The two groups performed equally well in the explicit task; however, autistic adults did not show anticipatory-looking behaviour in the false-belief trials of the implicit task. Critically, both groups showed the same attentional distribution in the implicit task prior to action prediction, indicating that autistic adults process information from social cues in the same way as non-autistic adults, but this information is not then used to update mental representations. Our findings further document that many autistic people struggle to spontaneously mentalize others' beliefs, and this non-verbal paradigm holds promise for use with a wide range of ages and abilities.

Children's anthropomorphism of inanimate agents

This review article examines the extant literature on animism and anthropomorphism in infants and young children. A substantial body of work indicates that both infants and young children have a broad concept of what constitutes a sentient agent and react to inanimate objects as they do to people in the same context. The literature has also revealed a developmental pattern in which anthropomorphism decreases with age, but social robots appear to be an exception to this pattern. Additionally, the review shows that children attribute psychological properties to social robots less so than people but still anthropomorphize them. Importantly, some research suggests that anthropomorphism of social robots is dependent upon their morphology and human-like behaviors. The extent to which children anthropomorphize robots is dependent on their exposure to them and the presence of human-like features. Based on the existing literature, we conclude that in infancy, a large range of inanimate objects (e.g., boxes, geometric figures) that display animate motion patterns trigger the same behaviors observed in child-adult interactions, suggesting some implicit form of anthropomorphism. The review concludes that additional research is needed to understand what infants and children judge as social agents and how the perception of inanimate agents changes over the lifespan. As exposure to robots and virtual assistants increases, future research must focus on better understanding the full impact that regular interactions with such partners will have on children's anthropomorphizing. This article is categorized under: Psychology > Learning Cognitive Biology > Cognitive Development Computer Science and Robotics > Robotics.

Dogs do not use their own experience with novel barriers to infer others' visual access

Despite extensive research into the Theory of Mind abilities in non-human animals, it remains controversial whether they can attribute mental states to other individuals or whether they merely predict future behaviour based on previous behavioural cues. In the present study, we tested pet dogs (in total, N = 92) on adaptations of the 'goggles test' previously used with human infants and great apes. In both a cooperative and a competitive task, dogs were given direct experience with the properties of novel screens (one opaque, the other transparent) inserted into identical, but differently coloured, tunnels. Dogs learned and remembered the properties of the screens even when, later on, these were no longer directly visible to them. Nevertheless, they were not more likely to follow the experimenter's gaze to a target object when the experimenter could see it through the transparent screen. Further, they did not prefer to steal a forbidden treat first in a location obstructed from the experimenter's view by the opaque screen. Therefore, dogs did not show perspective-taking abilities in this study in which the only available cue to infer others' visual access consisted of the subjects' own previous experience with novel visual barriers. We conclude that the behaviour of our dogs, unlike that of infants and apes in previous studies, does not show evidence of experience-projection abilities.

Meaning as mentalization

The way we establish meaning has been a profound question not only in language research but in developmental science as well. The relation between linguistic form and content has been loosened up in recent pragmatic approaches to communication, showing that code-based models of language comprehension must be augmented by context-sensitive, pragmatic-inferential mechanisms to recover the speaker's intended meaning. Language acquisition has traditionally been thought to involve building a mental lexicon and extracting syntactic rules from noisy linguistic input, while communicative-pragmatic inferences have also been argued to be indispensable. Recent research findings exploring the electrophysiological indicator of semantic processing, the N400, have raised serious questions about the traditional separation between semantic decoding and pragmatic inferential processes. The N400 appears to be sensitive to mentalization-the ability to attribute beliefs to social partners-already from its developmental onset. This finding raises the possibility that mentalization may not simply contribute to pragmatic inferences that enrich linguistic decoding processes but that the semantic system may be functioning in a fundamentally mentalistic manner. The present review first summarizes the key contributions of pragmatic models of communication to language comprehension. Then, it provides an overview of how communicative intentions are interpreted in developmental theories of communication, with a special emphasis on mentalization. Next, it discusses the sensitivity of infants to the information-transmitting potential of language, their ability to pick up its code-like features, and their capacity to track language comprehension of social partners using mentalization. In conclusion, I argue that the recovery of meaning during linguistic communication is not adequately modeled as a process of code-based semantic retrieval complemented by pragmatic inferences. Instead, the semantic system may establish meaning, as intended, during language comprehension and acquisition through mentalistic attribution of content to communicative partners.

Do toddlers reason about other people's experiences of objects? A limit to early mental state reasoning

Human social life requires an understanding of the mental states of one's social partners. Two people who look at the same objects often experience them differently, as a twinkling light or a planet, a 6 or a 9, and a random cat or Cleo, their pet. Indeed, a primary purpose of communication is to share distinctive experiences of objects or events. Here, we test whether toddlers (14-15 months) are sensitive to another agent's distinctive experiences of pictures when determining the goal underlying the agent's actions in a minimally social context. We conducted nine experiments. Across seven of these experiments (n = 206), toddlers viewed either videotaped or live events in which an actor, whose perspective differed from their own, reached (i) for pictures of human faces that were upright or inverted or (ii) for pictures that depicted a rabbit or a duck at different orientations. Then either the actor or the toddler moved to a new location that aligned their perspectives, and the actor alternately reached to each of the two pictures. By comparing toddlers' looking to the latter reaches, we tested whether their goal attributions accorded with the actor's experience of the pictured objects, with their own experience of the pictured objects, or with no consistency. In no experiment did toddlers encode the actor's goal in accord with his experiences of the pictures. In contrast, in a similar experiment that manipulated the visibility of a picture rather than the experience that it elicited, toddlers (n = 32) correctly expected the actor's action to depend on what was visible and occluded to him, rather than to themselves. In a verbal version of the tasks, older children (n = 35) correctly inferred the actor's goal in both cases. These findings provide further evidence for a dissociation between two kinds of mental state reasoning: When toddlers view an actor's object-directed action under minimally social conditions, they take account of the actor's visual access to the object but not the actor's distinctive experience of the object.

What is in an action? Preschool children predict that agents take previous paths and not previous goals

Developmental science has experienced a vivid debate on whether young children prioritize goals over means in their prediction of others' actions. Influential developmental theories highlight the role of goal objects for action understanding. Yet, recent infant studies report evidence for the opposite. The empirical evidence is therefore inconclusive. The current study advanced this debate by assessing preschool children's verbal predictions of others' actions. In five experiments (N = 302), we investigated whether preschool children and adults predict agents to move towards their previous goal (that is, show goal-related predictions) or predict agents to move along the same movement path that they pursued before. While Experiments 1a, 1b and 1c presented young children and adults with animated agents, Experiments 2a and 2b presented participants with human grasping action. An integrative analysis across experiments revealed that children were more likely to predict the agent to move along the same movement path, Z = -4.574, p ≤ 0.0001 (r = 0.304). That is, preschool children were more likely to predict that agents would move along the same trajectory even though this action would lead to a new goal object. Thus, our findings suggest that young children's action prediction relies on the detection of spatial and movement information. Overall, we discuss our findings in terms of theoretical frameworks that conceive of action understanding as an umbrella term that comprises different forms and facets in which humans understand others' actions. RESEARCH HIGHLIGHTS: We investigated whether preschool children predict agents to move towards their previous goal or to move along the same movement path that they pursued before. Unlike adults, preschool children predicted that agents would move along the same trajectory even though this action would lead to a new goal. Adults' goal-based predictions were affected from contextual details, whereas children systematically made path-based predictions. Young children's action prediction relies on the detection of spatial and movement information.

The pupil collaboration: A multi-lab, multi-method analysis of goal attribution in infants

The rise of pupillometry in infant research over the last decade is associated with a variety of methods for data preprocessing and analysis. Although pupil diameter is increasingly recognized as an alternative measure of the popular cumulative looking time approach used in many studies (Jackson & Sirois, 2022), an open question is whether the many approaches used to analyse this variable converge. To this end, we proposed a crowdsourced approach to pupillometry analysis. A dataset from 30 9-month-old infants (15 girls; Mage = 282.9 days, SD = 8.10) was provided to 7 distinct teams for analysis. The data were obtained from infants watching video sequences showing a hand, initially resting between two toys, grabbing one of them (after Woodward, 1998). After habituation, infants were shown (in random order) a sequence of four test events that varied target position and target toy. Results show that looking times reflect primarily the familiar path of the hand, regardless of target toy. Gaze data similarly show this familiarity effect of path. The pupil dilation analyses show that features of pupil baseline measures (duration and temporal location) as well as data retention variation (trial and/or participant) due to different inclusion criteria from the various analysis methods are linked to divergences in findings. Two of the seven teams found no significant findings, whereas the remaining five teams differ in the pattern of findings for main and interaction effects. The discussion proposes guidelines for best practice in the analysis of pupillometry data.

Neural correlates of theory of mind reasoning in congenitally blind children

Vision is an important source of information about other minds for sighted children, especially prior to the onset of language. Visually observed actions, eye gaze, and facial expressions of others provide information about mental states, such as beliefs, desires, and emotions. Does such experience contribute causally to the development of cortical networks supporting social cognition? To address this question we compared functional development of brain regions supporting theory of mind (ToM), as well as behavioral ToM reasoning, across congenitally blind (n=17) and sighted (n=114) children and adolescents (4-17 years old). We find that blind children in this age range show slightly lower ToM behavioral performance relative to sighted children. Likewise, the functional profile of ToM brain regions is qualitatively similar, but quantitatively weaker in blind relative to sighted children. Alongside prior research, these data suggest that vision facilitates, but is not necessary for, ToM development.

Mindreading by body: incorporating mediolateral balance and mouse-tracking measures to examine the motor basis of adults' false-belief tracking

The role played by motor representations in tracking others' belief-based actions remains unclear. In experiment 1, the dynamics of adults' anticipatory mediolateral motor activity (leftwards-rightwards leaning on a balance board) as well as hand trajectories were measured as they attempted to help an agent who had a true or false belief about an object's location. Participants' leaning was influenced by the agent's belief about the target's location when the agent was free to act but not when she was motorically constrained. However, the hand trajectories participants produced to provide a response were not modulated by the other person's beliefs. Therefore, we designed a simplified second experiment in which participants were instructed to click as fast as possible on the location of a target object. In experiment 2, mouse-movements deviated from an ideal direct path to the object location, with trajectories that were influenced by the location in which the agent falsely believed the object to be located. These experiments highlight that information about an agent's false-belief can be mapped onto the motor system of a passive observer, and that there are situations in which the motor system plays an important role in accurate belief-tracking.

Toddlers' social evaluations of agents who act on false beliefs

Mature social evaluations privilege agents' intentions over the outcomes of their actions, but young children often privilege outcomes over intentions in verbal tasks probing their social evaluations. In three experiments (N = 118), we probed the development of intention-based social evaluation and mental state reasoning using nonverbal methods with 15-month-old toddlers. Toddlers viewed scenarios depicting a protagonist who sought to obtain one of two toys, each inside a different box, as two other agents observed. Then, the boxes' contents were switched in the absence of the protagonist and either in the presence or the absence of the other agents. When the protagonist returned, one agent opened the box containing the protagonist's desired toy (a positive outcome), and the other opened the other box (a neutral outcome). When both agents had observed the toys move to their current locations, the toddlers preferred the agent who opened the box containing the desired toy. In contrast, when the agents had not seen the toys move and therefore should have expected the desired toy's location to be unchanged, the toddlers preferred the agent who opened the box that no longer contained the desired toy. Thus, the toddlers preferred the agent who intended to make the protagonist's desired toy accessible, even when its action, guided by a false belief concerning that toy's location, did not produce a positive outcome. Well before children connect beliefs to social behavior in verbal tasks, toddlers engage in intention-based evaluations of social agents with false beliefs.

Socially evaluative contexts facilitate mentalizing

Our ability to understand others' minds stands at the foundation of human learning, communication, cooperation, and social life more broadly. Although humans' ability to mentalize has been well-studied throughout the cognitive sciences, little attention has been paid to whether and how mentalizing differs across contexts. Classic developmental studies have examined mentalizing within minimally social contexts, in which a single agent seeks a neutral inanimate object. Such object-directed acts may be common, but they are typically consequential only to the object-seeking agent themselves. Here, we review a host of indirect evidence suggesting that contexts providing the opportunity to evaluate prospective social partners may facilitate mentalizing across development. Our article calls on cognitive scientists to study mentalizing in contexts where it counts.

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.

Infants differentiate between successful and failed communication in a false-belief context

Communication is based on social interaction, that is, interlocutors sharing attention to the intentions that they communicate about. In this study, we asked whether infants are aware of the fact that for information to be transferred, both interlocutors need to be present and share attention. Using a violation-of-expectation paradigm created to test infants' understanding of others' false beliefs, we asked whether 18-month-olds (n = 84) understood that correcting an agent's false belief via communication requires that the agent discerns the verbal statement. Participants saw how an agent put a toy into a box and left. An assistant then moved the toy into a cup. The intervention phase varied between three conditions: The agent and the assistant communicated about the actual location of the toy (full-communication), the agent was absent during the assistant's statement (incomplete-communication) or no communication took place (no-communication). At test, the agent reached into either the box or the cup. When no communication took place, infants expected the agent to search the toy at the original location. Full communication resulted in infants' expectations that the recipient's actions were altered, that is, the infants expected her to search the toy at the actual location. In contrast, incomplete communication did not yield clear expectations. Eighteen-month-olds thus seem to understand that for information to be transferred, it is a precondition that the recipient of the communicative act must be present and share attention during the communicator's statement. Only then communication can change a recipient's mental state.

Seeing the World From Others' Perspective: 14-Month-Olds Show Altercentric Modulation Effects by Others' Beliefs

Humans have a propensity to readily adopt others' perspective, which often influences their behavior even when it seemingly should not. This altercentric influence has been widely studied in adults, yet we lack an understanding of its ontogenetic origins. The current studies investigated whether 14-month-olds' search in a box for potential objects is modulated by another person's belief about the box's content. We varied the person's potential belief such that in her presence/absence an object was removed, added, or exchanged for another, leading to her true/false belief about the object's presence (Experiment 1, n = 96); or transformed into another object, leading to her true/false belief about the object's identity (i.e., the objects represented under a specific aspect, Experiment 2, n = 32). Infants searched longer if the other person believed that an object remained in the box, showing an altercentric influence early in development. These results suggest that infants spontaneously represent others' beliefs involving multiple objects and raise the possibility that infants can appreciate that others encode the world under a unique aspect.

Evidence for goal- and mixed evidence for false belief-based action prediction in two- to four-year-old children: A large-scale longitudinal anticipatory looking replication study

Unsuccessful replication attempts of paradigms assessing children's implicit tracking of false beliefs have instigated the debate on whether or not children have an implicit understanding of false beliefs before the age of four. A novel multi-trial anticipatory looking false belief paradigm yielded evidence of implicit false belief reasoning in three- to four-year-old children using a combined score of two false belief conditions (Grosse Wiesmann, C., Friederici, A. D., Singer, T., & Steinbeis, N. [2017]. Developmental Science, 20(5), e12445). The present study is a large-scale replication attempt of this paradigm. The task was administered three times to the same sample of N = 185 children at two, three, and four years of age. Using the original stimuli, we did not replicate the original finding of above-chance belief-congruent looking in a combined score of two false belief conditions in either of the three age groups. Interestingly, the overall pattern of results was comparable to the original study. Post-hoc analyses revealed, however, that children performed above chance in one false belief condition (FB1) and below chance in the other false belief condition (FB2), thus yielding mixed evidence of children's false belief-based action predictions. Similar to the original study, participants' performance did not change with age and was not related to children's general language skills. This study demonstrates the importance of large-scaled replications and adds to the growing number of research questioning the validity and reliability of anticipatory looking false belief paradigms as a robust measure of children's implicit tracking of beliefs. This article is protected by copyright. All rights reserved.

Beliefs for human-unique social learning

Phillips et al. argue that understanding what others know is central to social cognition across species and that this understanding underlies human-unique accumulation and transmission of cultural knowledge. Knowledge representations can't be both what we have in common with our evolutionary ancestors and what sets us apart from them. Belief representations are necessary for human-unique social learning.

Theory of mind in context: Mental-state representations for social evaluation

Whereas Phillips and colleagues argue that knowledge representations are more basic than belief representations, we argue that an accurate analysis of what is fundamental to theory of mind may depend crucially on the context in which mental-state reasoning occurs. Specifically, we call for increased study of the developmental trajectory of mental-state reasoning within socially evaluative contexts.

The Development of Giving in Forms of Object Exchange: Exploring the Roots of Communication and Morality in Early Interaction around Objects

Giving is an act of great social importance across cultures, with communicative as well as moral dimensions because it is linked to sharing and fairness. We critically evaluate various explanations for how this social process develops in infancy and take a process-relational approach, using naturalistic observations to illustrate forms of interaction involving the exchange of objects and possible developmental trajectories for the emergence of different forms of giving. Based on our data, we propose that the object becomes a pivot point for interaction, and through the process of such interaction the social actions of showing and giving emerge and take on diverse social meanings within the relations between infants and caregivers.

The posterior cerebellum supports implicit learning of social belief sequences

Recent studies have documented the involvement of the posterior cerebellar Crus (I & II) in social mentalizing, when sequences play a critical role. We investigated for the first time implicit learning of belief sequences. We created a novel task in which true and false beliefs of other persons were alternated in an adapted serial reaction time (SRT) paradigm (Belief SRT task). Participants observed two protagonists whose beliefs concerning reality were manipulated, depending on their orientation toward the scene (true belief: directly observing the situation) or away from it (false belief: knowing only the prior situation). Unbeknownst to the participants, a fixed sequence related to the two protagonists' belief orientations was repeated throughout the task (Training phase); and to test the acquisition of this fixed sequence, it was occasionally interrupted by random sequences (Test phase). As a nonsocial control, the two protagonists and their orientations were replaced by two different shapes of different colors respectively (Control SRT task). As predicted, the posterior cerebellar Crus I & II were activated during the Belief SRT task and not in the Control SRT task. The Belief SRT task revealed that Crus I was activated during the initial learning of the fixed sequence (Training phase) and when this learned sequence was interrupted by random sequences (Test phase). Moreover, Crus II was activated during occasional reappearance of the learned sequence in the context of sequence violations (Test phase). Our results demonstrate the contribution of the posterior cerebellar Crus during implicit learning and predicting new belief sequences.

Does syntax play a role in Theory of Mind development before the age of 3 years?

Language plays an important role in Theory of Mind development. Specifically, longitudinal and training studies indicate that the acquisition of complement syntax has an effect on three- to five-year-old children's mastery of the concept of false belief. There is evidence for both a beginning explicit understanding of the mind and mastery of complement syntax in children before their third birthday. In the present study, we investigated longitudinally whether an early sensitivity to complement syntax is related to early development of Theory of Mind abilities in a sample of N = 159 German-speaking 27- to 36-month-old children. Children's sensitivity to formal properties of complement syntax at 33 months was associated with their perspective-taking skills and their metacognition of own ignorance three months later. This relation remained significant when controlling for the effects of general language abilities. Furthermore, children's sensitivity to complement syntax was concurrently related to their early false belief understanding. These findings support the view that complement syntax shares representational demands with an understanding of epistemic states and that language begins to support the acquisition of epistemic concepts earlier than was previously thought.

Implicit Learning of True and False Belief Sequences

To investigate whether people can implicitly learn regularities in a social context, we developed a new implicit sequence learning task combining elements from classic false belief and serial reaction time tasks. Participants learned that protagonists were offered flowers at four locations. The protagonists' beliefs concerning the flowers were true or false, depending on their orientation, respectively, toward the scene (so that the flowers could be seen) or away from it. Unbeknown to the participants, there was a fixed belief-related sequence involving three dimensions (identity of the two protagonists, true-false belief orientation held by the protagonists, and flower location as believed by the protagonists). Participants had to indicate as fast as possible where the flowers were located (Experiment 1), or how many flowers were given (Experiment 2) according to the protagonists. Experiment 1 combined perceptual and motor processes (as both the belief-related sequence and motor responses referred to location), whereas Experiment 2 unconfounded the sequence and motor responses, allowing to investigate pure perceptual implicit learning. For reasons of comparison, two non-social conditions were created in Experiment 2 by replacing the protagonists with two non-social objects-colored cameras or shapes. Results revealed significant implicit sequence learning of all belief-related dimensions in Experiment 1, and of true-false belief orientation in Experiment 2, even without a motor confound. Importantly, there were faster reaction times and stronger sequence learning effects in the social than in the non-social conditions. The present findings demonstrate for the first time that people are able to implicitly learn belief-related sequences.

Can infants adopt underspecified contents into attributed beliefs? Representational prerequisites of theory of mind

Recent evidence suggests that young infants, as well as nonhuman apes, can anticipate others' behavior based on their false beliefs. While such behaviors have been proposed to be accounted by simple associations between agents, objects, and locations, human adults are undoubtedly endowed with sophisticated theory of mind abilities. For example, they can attribute mental contents about abstract or non-existing entities, or beliefs whose content is poorly specified. While such endeavors may be human specific, it is unclear whether the representational apparatus that allows for encoding such beliefs is present early in development. In four experiments we asked whether 15-month-old infants are able to attribute beliefs with underspecified content, update their content later, and maintain attributed beliefs that are unknown to be true or false. In Experiment 1, infants observed as an agent hid an object to an unspecified location. This location was later revealed in the absence or presence of the agent, and the object was then hidden again to an unspecified location. Then the infants could search for the object while the agent was away. Their search was biased to the revealed location (that could be represented as the potential content of the agent's belief when she had not witnessed the re-hiding), suggesting that they (1) first attributed an underspecified belief to the agent, (2) later updated the content of this belief, and (3) were primed by this content in their own action even though its validity was unknown. This priming effect was absent when the agent witnessed the re-hiding of the object, and thus her belief about the earlier location of the object did not have to be sustained. The same effect was observed when infants searched for a different toy (Experiment 2) or when an additional spatial transformation was introduced (Experiment 4), but not when the spatial transformation disrupted belief updating (Experiment 3). These data suggest that infants' representational apparatus is prepared to efficiently track other agents' beliefs online, encode underspecified beliefs and define their content later, possibly reflecting a crucial characteristic of mature theory of mind: using a metarepresentational format for ascribed beliefs.

Three-year-olds' spontaneous lying in a novel interaction-based paradigm and its relations to explicit skills and motivational factors

Previous research has investigated children's lying and its motivational and social-cognitive correlates mostly through explicit tasks. The current study used an anticipatory interaction-based paradigm adopted from research with preverbal infants. We investigated 3-year-olds' spontaneous lying within interaction and its motivational basis and relations to explicit skills of lying, false belief understanding, inhibitory control, and socialization. Children interacted with puppets to secure stickers that were hidden in one of two boxes. Either a friend or a competitor puppet tried to obtain the stickers. Nearly all children helpfully provided information about the sticker's location to the friend, and about half of the sample anticipatorily provided false information to the competitor. Children misinformed the competitor significantly more often than the friend, both when the reward was for themselves and when it was for someone else. Explicitly planning to lie in response to a question occurred significantly less often but predicted spontaneous lying, as did passing the explicit standard false belief task. Thus, by 3 years of age, children spontaneously invoke false beliefs in others. This communicative skill reveals an interactional use of false belief understanding in that it requires holding one's perspective to pursue one's goal while providing a different perspective to distract a competitor. Findings support the view that practical theory of mind skills emerge for social coordination and serve as a basis for developing explicit false belief reasoning.

Machiavellian strategist or cultural learner? Mentalizing and learning over development in a resource-sharing game

Theorists have sought to identify the key selection pressures that drove the evolution of our species' cognitive abilities, life histories and cooperative inclinations. Focusing on two leading theories, each capable of accounting for many of the rapid changes in our lineage, we present a simple experiment designed to assess the explanatory power of both the Machiavellian Intelligence and the Cultural Brain/Intelligence Hypotheses. Children (aged 3-7 years) observed a novel social interaction that provided them with behavioural information that could either be used to outmanoeuvre a partner in subsequent interactions or for cultural learning. The results show that, even after four rounds of repeated interaction and sometimes lower pay-offs, children continued to rely on copying the observed behaviour instead of harnessing the available social information to strategically extract pay-offs (stickers) from their partners. Analyses further reveal that superior mentalizing abilities are associated with more targeted cultural learning - the selective copying of fewer irrelevant actions - while superior generalized cognitive abilities are associated with greater imitation of irrelevant actions. Neither mentalizing capacities nor more general measures of cognition explain children's ability to strategically use social information to maximize pay-offs. These results provide developmental evidence favouring the Cultural Brain/Intelligence Hypothesis over the Machiavellian Intelligence Hypothesis.

Implicit Theory of Mind under realistic social circumstances measured with mobile eye-tracking

Recently, there has been a debate whether implicit Theory of Mind can be reliably measured using anticipatory looking tasks. Previous anticipatory looking paradigms used video stimuli to measure implicit Theory of Mind; however, numerous replications of these paradigms were unsuccessful. This lack of replications may be due to video stimuli not being sufficiently engaging. As Theory of Mind is an inherently social phenomenon, robust evidence might only be observed in a real social situation. Therefore, the current preregistered study aimed to test anticipatory looking with real-life social stimuli. A mobile eye-tracker was used to measure gaze patterns indicative of Theory of Mind while participants observed a real-life interaction of an experimenter and a confederate. The realistic scenario did not provide clear evidence for implicit Theory of Mind. Furthermore, anticipatory looking behavior did not reliably occur during familiarization trials, in line with previous research. However, looking patterns were slightly more in line with belief tracking than in some more controlled studies using video stimuli. In general, implicit Theory of Mind was not reliably reflected in anticipatory looking patterns even if they were measured in realistic social situations. This questions the suitability of anticipatory looking measures for implicit Theory of Mind.

Infants Generalize Beliefs Across Individuals

It has been argued that infants possess a rich, sophisticated theory of mind (ToM) that is only revealed with tasks based on spontaneous responses. A mature (ToM) implies the understanding that mental states are person specific. Previous studies on infants' understanding of motivational mental states, such as goals and preferences have revealed that, by 9 months of age, infants do not generalize these motivational mental states across agents. However, it remains to be determined if infants also perceive epistemic states as person specific. Therefore, the goal of the present study was to use a switch agent paradigm with the classic false belief violation-of-expectation task. Results revealed that 16-month-old infants attributed true and false beliefs to a naïve agent - they did not perceive beliefs as person specific. These findings indicate that the mechanisms that underlie infants' implicit attribution of beliefs differ from those assumed for explicit reasoning about beliefs.

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.

Metacognition and mindreading in young children: A cross-cultural study

Prior studies document cross cultural variation in the developmental onset of mindreading. In particular, Japanese children are reported to pass a standard false belief task later than children from Western countries. By contrast, we know little about cross-cultural variation in young children's metacognitive abilities. Moreover, one prominent theoretical discussion in developmental psychology focuses on the relation between metacognition and mindreading. Here we investigated the relation between mindreading and metacognition (both implicit and explicit) by testing 4-year-old Japanese and German children. We found no difference in metacognition between the two cultural groups. By contrast, Japanese children showed lower performance than German children replicating cultural differences in mindreading. Finally, metacognition and mindreading were not related in either group. We discuss the findings in light of the existing theoretical accounts of the relation between metacognition and mindreading.

Theory of mind development: State of the science and future directions

This chapter offers a brief overview of how research on theory of mind development has developed over the recent years, with a focus on current research and theoretical accounts of theory of mind during the infancy period. The topics covered include the factors contributing to individual differences in theory of mind skills in preschoolers, the current replication crisis in theory of mind in infancy, the stability of theory of mind from infancy to childhood, and recent research suggesting that infants' concept of false belief is, at best, immature (e.g., overattribution to inanimate agents). Future directions in theory of mind research are suggested.

Do Non-Human Primates Really Represent Others' Beliefs?

Over two decades of research have produced compelling evidence that non-human primates understand some psychological states in other individuals but are unable to represent others' beliefs. Recently, three studies employing anticipatory looking (AL) paradigms reported that non-human primates do show hints of implicitly understanding the beliefs of others. However, measures of AL have been increasingly scrutinized in the human literature owing to extensive replication problems. We argue that new reports of belief representation in non-human primates using AL should be interpreted cautiously because of methodological and theoretical challenges paralleling trends in the human literature. We explore how future work can address these challenges, and conclude by identifying new evolutionary questions raised by the prospect that non-human primates implicitly represent others' beliefs without an explicit belief representation system that guides fitness-relevant behavior.

Psychological Mechanisms Forged by Cultural Evolution

The adaptive features of cognitive mechanisms, the features that make them fit for purpose, have traditionally been explained by nature and nurture. In the last decade, evidence has emerged that distinctively human cognitive mechanisms are also, and predominantly, shaped by culture. Like physical technology, human cognitive mechanisms are inherited via social interaction and made fit for purpose by culture evolution. This article surveys evidence from developmental psychology, comparative psychology, and cognitive neuroscience indicating that imitation, mentalizing, and language are “cognitive gadgets” shaped predominantly by cultural evolution. This evidence does not imply that the minds of newborn babies are blank slates. Rather, it implies that genetic evolution has made subtle changes to the human mind, allowing us to construct cognitive gadgets in the course of childhood through cultural learning.

Spontaneous theory of mind in adults with attention-deficit/hyperactivity disorder

Spontaneous theory of mind (ToM) is an unconscious and automatic understanding of others' mental states. Recently, individuals with attention-deficit hyperactivity disorder (ADHD) have been shown to have social and communication difficulties, and ToM in ADHD has come under scrutiny. Although some studies have employed explicit ToM tasks to this end with contradictory results, none, to our knowledge, has investigated spontaneous ToM in individuals with ADHD. Therefore, we performed this study to examine implicit mentalizing in adults with ADHD using the anticipatory-looking paradigm designed by Senju et al. (2009) with a sample of 24 adults with ADHD and 18 neurotypical adults. The total fixation times to three areas of interest, i.e., the actor and the false-belief congruent and incongruent sides of the scene were measured. We found that neither group showed looking bias toward either the false-belief congruent or incongruent side. We interpret that this similar gaze pattern and the absence of looking bias to the false-belief incongruent side in both groups is indicative of intact implicit ToM in adults with ADHD. Adults with ADHD looked significantly less at the actor than did neurotypical individuals, possibly due to inattention and further experimental modifications should be considered.

On the domain specificity of the mechanisms underpinning spontaneous anticipatory looks in false-belief tasks

Many studies proposed that infants' and adults' looking behavior suggest a spontaneous and implicit ability to reason about others' beliefs. It has been argued, however, that these successes are false positives due to domain-general processes, such as retroactive interference. In this study, we investigated the domain specificity of mechanisms underpinning participants' looking behavior by manipulating the dynamic cues in the event stimuli. Infants aged 15 and 20 months and adults saw animation events in which either a self-moving triangle, or a hand holding an identical inert triangle, chased an animated disk. Most 20-month-olds and adults showed belief congruent anticipatory looks in the agent-triangle condition, whereas they showed no bias in the inert triangle control condition. These results are not consistent with submentalizing accounts based on domain-general low-level processes and provide further support for domain-specific explanations positing an early-emerging mentalistic reasoning.

Two systems for thinking about others' thoughts in the developing brain

The ability to reason about other people’s thoughts and beliefs characterizes the complex social interaction among humans. This ability, called Theory of Mind (ToM), has long been argued to develop around 4 y when children start explicitly reasoning about others' beliefs. However, when tested nonverbally, infants already show action expectations congruent with others’ beliefs before the age of 2 y. Do these behaviors reflect different systems for understanding others’ minds—an early and a later developing one—or when does ToM develop? We show that these abilities are supported by the maturation of independent brain networks, suggesting different systems for explicit verbal ToM and early nonverbal action expectations.

Human social interaction crucially relies on the ability to infer what other people think. Referred to as Theory of Mind (ToM), this ability has long been argued to emerge around 4 y of age when children start passing traditional verbal ToM tasks. This developmental dogma has recently been questioned by nonverbal ToM tasks passed by infants younger than 2 y of age. How do young children solve these tests, and what is their relation to the later-developing verbal ToM reasoning? Are there two different systems for nonverbal and verbal ToM, and when is the developmental onset of mature adult ToM? To address these questions, we related markers of cortical brain structure (i.e., cortical thickness and surface area) of 3- and 4-y-old children to their performance in novel nonverbal and traditional verbal TM tasks. We showed that verbal ToM reasoning was supported by cortical surface area and thickness of the precuneus and temporoparietal junction, classically involved in ToM in adults. Nonverbal ToM reasoning, in contrast, was supported by the cortical structure of a distinct and independent neural network including the supramarginal gyrus also involved in emotional and visual perspective taking, action observation, and social attention or encoding biases. This neural dissociation suggests two systems for reasoning about others’ minds—mature verbal ToM that emerges around 4 y of age, whereas nonverbal ToM tasks rely on different earlier-developing possibly social-cognitive processes.

Illuminating the Dark Ages: Pupil Dilation as a Measure of Expectancy Violation Across the Life Span

Mainly for methodological reasons, little is known about the course of development of early cognitive competencies diagnosed with the violation of expectation (VoE) method in infants. The goal of this research was to evaluate the use of pupillometry as a unified approach to assess expectancy violations during and beyond the "dark ages" between 1 and 3 years. We tested children aged 1-6 years and adults (N = 279) with pictures of animals combined with matching or mismatching animal sounds. All age groups exhibited significantly greater pupil dilation in mismatched than matched trials. We conclude that pupillometry is a viable alternative to the VoE method that, by contrast to the latter, can be used throughout the life span.

What is mindreading?

Theory of mind, also known as mindreading, refers to our ability to attribute mental states to agents in order to make sense of and interact with other agents. Recently, theorists in this literature have advanced a broad conception of mindreading. In particular, psychologists and philosophers have examined how we attribute knowledge, intention, mentalistically loaded stereotypes, and personality traits to others. Moreover, the diversity of our goals in a social interaction-precision, efficiency, self/in-group protection-generates diversity in the mindreading processes we employ. Finally, the products of mindreading are varied, as well. We produce different sorts of mindreading explanations depending on our epistemic goals and the situational context. In this article, I piece together these different strands of research to present a broad conception of mindreading that is complex, messy, and interesting. This article is categorized under: Philosophy > Knowledge and Belief Philosophy > Psychological Capacities.