Infants in the second year of life have demonstrated pragmatic competence by considering a communicating partner’s epistemic state to home in on their intended meaning. Here we provide a new investigation into this ability using the N400 ERP component to index semantic processing and thus removing extraneous task demands that may be difficult for children of this age. Nineteen-month-old infants watched trials in which an agent placed a novel object into a box, and then either saw (seen swap) or did not see (unseen swap) it replaced with a second novel object. The agent then pointed at the box and provided a novel label. We measured the N400 ERP component in response to this novel label, which while unfamiliar, was likely correct in the seen swap-, and incorrect in the unseen swap trials. If infants interpret the agent’s referential information as likely incorrect when she has not seen the swap, they may show a semantic mismatch effect indicated by a larger negativity for unseen-swap trials. However, infants exhibited a significantly larger amplitude N400 in response to the novel label when the agent had seen the object switch, than when she had not. This indicates that infants considered the speaker’s epistemic state and the N400 effect reflected greater engagement in establishing a word-referent link when the communicator’s reference was likely correct, possibly due to an effort towards word learning. This interpretation is supported by a strong correlation between the N400 amplitude and infants’ parent-reported receptive vocabulary, suggesting a possible link between ability to interpret others’ communicative intention based on their epistemic access, and word acquisition.

Human infants are geared towards others in their environment, use others to select what to learn, and are selective in who they learn from. How infants relate to others is affected by a range of factors in social interactions, one of which is interpersonal synchrony: infants prefer synchronous social partners and are more willing to help others they moved in synchrony with. Here, we investigated whether interpersonal synchrony affects infants' imitation and social alignment, around the age when they develop a self-concept. As a marker of self-concept, we first administered the mirror self-recognition test. Then infants were bounced (a-)synchronously with an experimenter. Next, they saw the same experimenter wearing a sticker on her face and could choose between two stickers, one matching the experimenter's. Infants who showed evidence for a cognitive self were more likely to choose the matching sticker following asynchronous movement. Possibly, a conceptual self allows them to appreciate that they can actively intervene to bring about alignment. Infants also pointed more following asynchrony, suggesting that self-other distinction may sensitize infants to consider others' distinct perspective. In the imitation task, infants in the synchrony condition were somewhat more likely to imitate the suboptimal actions of the experimenter, indicating that interpersonal synchrony may enhance social learning. We conclude that interpersonal synchrony can highlight self-other similarity or lack thereof to infants - an important social cue that affects how they align with others, communicate and learn from them, especially once they are able to conceive of their own self.

A decade of ManyBabies research, testing thousands of babies across hundreds of labs, has shown that some, but not all findings in infant research replicate well. Collectively, these projects have shown us that our methods carry limitations that larger samples alone cannot resolve. Here we present three lessons that point toward a more reliable, inclusive developmental science.

The development of self-regulation is a foundational milestone of early childhood, predicting outcomes from future academic success to mental health throughout the lifespan. Accumulating behavioral research suggests that self-regulation is not innate but socially constructed, originating in "co-regulatory" interactions where caregivers modulate a child's arousal and attention. However, the neural mechanisms supporting the transition from external regulation to internal capacity remain poorly understood. This opinion piece proposes that interpersonal neural synchrony (INS), the temporal alignment of brain activity between interacting partners, serves as a critical biomarker of this transition. We synthesize evidence linking INS to both co-regulation and to self-regulation strategies, arguing that INS may serve as the neural bridge that facilitates the transmission of regulatory competence from dyadic to independent regulation. We identify critical research gaps and propose a framework in which INS is no longer understood solely as a marker of interpersonal dependency, but as a dynamic mechanism supporting the development of autonomy.

Do toddlers and adults engage in spontaneous Theory of Mind? This multi-lab collaboration examined whether 18- to 27-month-olds’ and adults’ anticipatory looks distinguish between two basic forms of epistemic states: knowledge and ignorance. In adults (n = 703, 68% female), we found clear evidence that they do: they showed simple goal-based action anticipation and differentiated between knowledge and ignorance conditions. In toddlers (n = 521, 49% female), results were less conclusive. While demonstrating goal-based action anticipation, they did not differentiate between knowledge and ignorance as predicted. Future research can explore adults’ sensitivity to more complex epistemic states like true/false beliefs and clarify whether toddlers’ results reflect competence or performance limitations.

A decade of ManyBabies research, testing thousands of babies across hundreds of labs, has shown that some, but not all findings in infant research replicate well. Collectively, these projects have shown us that our methods carry limitations that larger samples alone cannot resolve. Here we present three lessons that point toward a more reliable, inclusive developmental science.

Children's capacity to regulate their impulses increases during early years, supported by their caregivers' co-regulation. The questionnaire IMMA (Impulse-Management in the Caregiver-Child Dyad; Pauen et al., 2019) assesses (1) parental ideas and goals regarding child self-regulation development, (2) child self-regulation strategies, and (3) parental co-regulation strategies. A total of N = 2,478 parents from Denmark, Germany, Italy, and Poland with children aged 1-6 years (M = 36.34, range 12-83 months) filled out the IMMA short-form online. The factor structure reached an adequate model fit in all countries and closely resembled that of the original version, with few interesting exceptions. Cross-sectional analyses revealed that parents' expectations regarding child self-regulation development, children's self-regulation-, and parents' co-regulation strategies changed dynamically throughout early childhood. Based on the findings, we conclude that the IMMA-SF provides a valid instrument to further explore this interplay across development.

Do toddlers and adults engage in spontaneous Theory of Mind? This multi-lab collaboration examined whether 18- to 27-month-olds’ and adults’ anticipatory looks distinguish between two basic forms of epistemic states: knowledge and ignorance. In adults (n = 703, 68% female), we found clear evidence that they do: they showed simple goal-based action anticipation in pilot studies and differentiated between knowledge and ignorance conditions in the main study. In toddlers (n = 521, 49% female), results were less conclusive. While demonstrating goal-based action anticipation in pilot studies, they did not differentiate between knowledge and ignorance as predicted. Future research can explore adults’ sensitivity to more complex epistemic states like true/false beliefs and clarify whether toddlers’ results reflect competence or performance limitations.

Abstract: Children’s capacity to regulate their impulses increases during early years, supported by their caregivers’ co-regulation. The questionnaire IMMA (Impulse-Management in the Caregiver-Child Dyad; Pauen et al., 2019 ) assesses (1) parental ideas and goals regarding child self-regulation development, (2) child self-regulation strategies, and (3) parental co-regulation strategies. A total of N = 2,478 parents from Denmark, Germany, Italy, and Poland with children aged 1–6 years ( M = 36.34, range 12–83 months) filled out the IMMA short-form online. The factor structure reached an adequate model fit in all countries and closely resembled that of the original version, with few interesting exceptions. Cross-sectional analyses revealed that parents’ expectations regarding child self-regulation development, children’s self-regulation-, and parents’ co-regulation strategies changed dynamically throughout early childhood. Based on the findings, we conclude that the IMMA-SF provides a valid instrument to further explore this interplay across development.

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.

When infants start mastering their first language, they may start to notice when words are used incorrectly. Around 14-months of age, infants detect incorrect labeling when they are presented with an object which is labeled while still visible. However, things that are referred to are often out of sight when we communicate about them. The present study examined infants’ detection of semantic mismatch when the object was occluded at the time of labeling. Specifically, we investigated whether mislabeling that referred to an occluded object could elicit a semantic mismatch. We showed 14-month-old Danish-speaking infants events where an onscreen agent showed an object and then hid it in a box. This was followed by another agent’s hand pointing at the box, and a concurrent auditory category label played, which either matched or did not match the hidden object. Our results indicate that there is an effect of semantic mismatch with a larger negativity in incongruent trials. Thus, infants detected a mismatch, as indicated by a larger n400, when occluded objects were mislabeled. This finding suggests that infants can sustain an object representation in memory and compare it to a semantic representation of an auditory category label.

Human infants may exhibit an altercentric bias, where the perspective of others biases theirown cognition. This bias may serve a crucial learning function in early ontogeny. This worktested the two main predictions of an altercentric bias in 14-month-old infants: (i) conceptualinformation should also be encoded altercentrically, and (ii) the other’s perspective maycompletely override infants’ own processing. We probed if infants detect a semantic mismatchif 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 toincongruent, 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 theother’s. These findings demonstrate a strong altercentric bias that prioritizes encodingconceptual information from others’ perspective during early development.

People sometimes commit ‘egocentric errors’, failing to ignore their own perspective when interpreting others’ communication. Training imitation-inhibition, when participants perform the opposite action from another person, facilitates subsequent perspective-taking in adults. This study tested whether imitation-inhibition training also facilitates perspective-taking in 3-6-year-olds, an age where egocentric perspective may be particularly influential. Children participated in a 10-minute imitation-inhibition, imitation, or non-social-inhibition training (white, n=25 per condition, 33 female, period: 2018-2021), then the communicative-perspective-taking Director task. Training had a significant effect (F(2, 71) = 3.316, p = .042, η2 = .085): on critical trials the imitation-inhibition-group selected the correct object more often than the other groups. Imitation-inhibition training specifically enhanced the perspective-taking process possibly by highlighting the distinction between self and other.

Young learners would seem to face a daunting challenge in selecting to what they should attend, a problem that may have been exacerbated in human infants by changes in carrying practices during human evolution. A novel theory proposes that human infant cognition has an altercentric bias whereby early in life, infants prioritize encoding events that are the targets of others’ attention. We tested for this bias by asking whether, when the infant and an observing agent have a conflicting perspective on an object's location, the co-witnessed location is better remembered. We found that 8- but not 12-month-olds expected the object to be at the location where the agent had seen it. These findings suggest that in the first year of life, infants may prioritize the encoding of events to which others attend, even though it may sometimes result in memory errors. However, the disappearance of this bias by 12 months suggests that altercentricism is a feature of very early cognition. We propose that it facilitates learning at a unique stage in the life history when motoric immaturity limits infants' interaction with the environment; at this stage, observing others could maximally leverage the information selection process.

When infants start mastering their first language, they may start to notice when words are used incorrectly. Around 14-months of age, infants detect incorrect labeling when they are presented with an object which is labeled while still visible. However, things that are referred to are often out of sight when we communicate about them. The present study examined infants’ detection of semantic mismatch when the object was occluded at the time of labeling. Specifically, we investigated whether mislabeling that referred to an occluded object could elicit a semantic mismatch. We showed 14-month-old Danish-speaking infants events where an onscreen agent showed an object and then hid it in a box. This was followed by another agent’s hand pointing at the box, and a concurrent auditory category label played, which either matched or did not match the hidden object. Our results indicate that there is an effect of semantic mismatch with a larger negativity in incongruent trials. Thus, infants detected a mismatch, as indicated by a larger n400, when occluded objects were mislabeled. This finding suggests that infants can sustain an object representation in memory and compare it to a semantic representation of an auditory category label.

As adults, not only do we choose what we prefer, we also tend to adapt our preferences according to our previous choices. We do this even when choosing blindly and we could not have had any previous preference for the option we chose. These blind choice-induced preferences are thought to result from cognitive dissonance as an effort to reconcile our choices and values. In the present preregistered study, we asked when this phenomenon develops. We reasoned that cognitive dissonance may emerge around 2 years of age in connection with the development of children's self-concept. We presented N = 200 children aged 16 to 36 months with a blind choice between two toys, and then tested whether their choice had induced a preference for the chosen, and a devaluation of the discarded, toy. Indeed, children's choice-induced preferences substantially increased with age. 26- to 36-months-old children preferred a neutral over the previously blindly discarded toy, but the previously chosen over the neutral toy, in line with cognitive dissonance predictions. Younger infants showed evidence against such blind choice-induced preferences, indicating its emergence around 2 years of age. Contrary to our hypotheses, the emergence of blind choice-induced preferences was not related to measures of self-concept development in the second year of life. Our results suggest that cognitive dissonance develops around 2 years. We speculate about cognitive mechanisms that underlie this development, including later-developing aspects of the self-concept and increasingly abstract representational abilities.

Young learners would seem to face a daunting challenge in selecting to what they should attend, a problem that may have been exacerbated in human infants by changes in carrying practices during human evolution. A novel theory proposes that human infant cognition has an altercentric bias whereby early in life, infants prioritize encoding events that are the targets of others’ attention. We tested for this bias by asking whether, when the infant and an observing agent have a conflicting perspective on an object’s location, the co-witnessed location is better remembered. We found that 8- but not 12-month-olds expected the object to be at the location where the agent had seen it. These findings suggest that in the first year of life, infants may prioritize the encoding of events to which others attend, even though it may sometimes result in memory errors. However, the disappearance of this bias by 12 months suggests that altercentricism is a feature of very early cognition. We propose that it facilitates learning at a unique stage in the life history when motoric immaturity limits infant’s interaction with the environment; at this stage observing others could maximally leverage the information selection process.

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.