Relation of infants' and mothers' pointing to infants' vocabulary measured directly and with parental reports.

Infants' and parents' pointing gestures predict infants' concurrent and prospective language development. Most studies have measured vocabulary size using parental reports. However, parents tend to underestimate or overestimate infants' vocabulary necessitating the use of direct measures alongside parent reports. The present study examined whether mothers' index-finger pointing, and infants' whole-hand and index-finger pointing at 14 months associate with infants' receptive and expressive vocabulary based on parental reports and directly measured lexical processing efficiency (LPE) concurrently at 14 months and prospectively at 18 months. We used the decorated room paradigm to measure pointing frequency, the Turkish communicative development inventory I to measure infants' receptive vocabulary, Turkish communicative development inventory II to measure their expressive vocabulary, and the Looking-While-Listening (LWL) task to measure LPE. At 14 months, 34 mother-infant dyads, and at 18 months, 30 dyads were included in the analyses. We found that only infants' index-finger pointing frequency at 14 months predicted their LPE (both reaction time and accuracy) prospectively at 18 months but not concurrently at 14 months. Neither maternal pointing nor infants' pointing predicted their receptive and expressive vocabulary based on indirect measurement. The results extend the evidence on the relation between index-finger pointing and language development to a more direct measure of vocabulary.

Correlates of infant pointing frequency in the first year.

This study examines the emergence of concurrent correlates of infant pointing frequency with the aim of contributing to its ontogenetic theories. We measured monthly from 8 to 12 months infants' (N = 56) index-finger pointing frequency along with several candidate correlates: (1) family socioeconomic status (SES), (2) mothers' pointing production, and (3) infants' point following to targets in front of and behind them. Results revealed that (1) infants increased their pointing frequency across age, but high-SES infants had a steeper increase, and a higher pointing frequency than low-SES infants from 10 months onward, (2) maternal pointing frequency was not associated with infant pointing frequency at any age, (3) infants' point following abilities to targets behind their visual fields was positively associated with their pointing frequency at 12 months, after pointing had already emerged around 10 months. Findings suggest that family SES impacts infants' pointing development more generally, not just through maternal pointing. The association between pointing and following points to targets behind, but not in front, suggests that a higher level of referential understanding emerges after, and perhaps through the production of pointing.

Don't miss the chance to reap the fruits of recent advances in behavioral genetics.

In her target article, Burt revives a by now ancient debate on nature and nurture, and the ways to measure, disentangle, and ultimately trust one or the other of these forces. Unfortunately, she largely dismisses recent advances in behavior genetics and its huge potential in contributing to a better prediction and understanding of complex traits in social sciences.

Ontogeny of index-finger pointing.

Index-finger pointing is foundational to language acquisition. Less is known about its emergence. In lab-based monthly longitudinal assessments from 8-13 months (N = 31) the study measured longitudinal predictors of index-finger pointing: parent pointing and infants' earlier emerging showing, hand-pointing, and point-following. All behaviors increased significantly with age and showed inter-individual stability. At 11 months all behaviors except hand pointing were synchronously interrelated, with no evidence for an earlier synchronous interrelation between behaviors. Caregiver pointing and infants' earlier behaviors longitudinally predicted the age of emergence of index-finger pointing. An additional cross-sectional comparison of parent pointing at 5 and 7 months (N = 44) showed that significantly fewer caregivers of 5- compared to 7-month-olds pointed for their infants. Findings suggest that pointing emerges as an outcome of social co-construction across the first year of life.

Marked pointing facilitates learning part names: A test of lexical constraint versus social pragmatic accounts of word learning.

The empirical study of word learning is driven by a theoretical debate between lexical constraint and social-pragmatic accounts; it has still not been determined which of these two best explains the evidence. We investigated whether the markedness of a pointing accompanying a verbal reference could help to learn a part name. Participants were 35 two-and-a-half-year-olds, 42 four-and-a-half-year-olds, and 38 undergraduate university students in Japan. The experimenter pointed to a novel part (embedded in a novel whole object) with either "marked" pointing, which was touching the part with a small circular motion, or with usual pointing. Touch accompanied by circular motion reliably elicited learning of part names in all age groups. Usual distal pointing without motion reliably elicited learning of whole object names. The pattern of findings rejects a whole-object constraint in early word learning and demonstrates that marked pointing can promote learning novel part names, supporting a social-pragmatic account.

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.

Inferring hidden objects from still and communicative onlookers at 8, 14, and 36 months of age.

The current study investigated across five eye-tracking experiments children's developing skill of adopting others' referential perspective (Level 1 perspective taking) and to what extent it involves automatic processes or requires ostensive communicative cues. Three age groups (8-, 14-, and 36-month-olds) were tested on their expectation of an object appearing behind one of two peripheral occluders. A centrally presented person in profile either provided an ostensive communicative pointing cue or sat still, oriented to one of the two occluders. The 14-month-olds anticipated the hidden object when the onlooker had communicatively pointed to the location, as revealed by faster target detection in congruent trials (latency effect) and longer dwell times to the empty side in incongruent trials (violation-of-expectation effect). This was not the case when a still person was only oriented to one side. Adding emotional expressions to the still person (Experiment 2) did not help to produce the effects. However, at 36 months of age (Experiment 3), children showed both effects for the still person. The 8-month-olds did not show the violation-of-expectation effect for communicative pointing (Experiment 4) or for a matched abbreviated reach (Experiment 5b), showing it only for a complete reach behind the occluder (Experiment 5a), although they were faster to detect the congruent object in Experiment 4 and 5a. Findings reveal that automatic perspective taking develops after communicative perspective taking and that communicative perspective taking is a developmental outcome of the first year of life. The developmental pattern suggests a continuous social construction process of perspective-taking skills.

The development of gaze following in monolingual and bilingual infants: A multi-laboratory study.

Determining the meanings of words requires language learners to attend to what other people say. However, it behooves a young language learner to simultaneously encode relevant non-verbal cues, for example, by following the direction of their eye gaze. Sensitivity to cues such as eye gaze might be particularly important for bilingual infants, as they encounter less consistency between words and objects than monolingual infants, and do not always have access to the same word-learning heuristics (e.g., mutual exclusivity). In a preregistered study, we tested the hypothesis that bilingual experience would lead to a more pronounced ability to follow another's gaze. We used a gaze-following paradigm developed by Senju and Csibra (Current Biology, 18, 2008, 668) to test a total of 93 6- to 9-month-old and 229 12- to 15-month-old monolingual and bilingual infants, in 11 laboratories located in 8 countries. Monolingual and bilingual infants showed similar gaze-following abilities, and both groups showed age-related improvements in speed, accuracy, frequency, and duration of fixations to congruent objects. Unexpectedly, bilinguals tended to make more frequent fixations to on-screen objects, whether or not they were cued by the actor. These results suggest that gaze sensitivity is a fundamental aspect of development that is robust to variation in language exposure.

Decontextualized talk in caregivers' input to 12-month-old children during structured interaction.

Decontextualized talk is assumed to be used only rarely when children are younger than 30 months. Motivated by Bühler's (1934/1999) linguistic theory that describes different dimensions of (de-)contextualization, we provide evidence that this kind of input can already be found in caregivers' talking to their 12-month-old children. Such early input is characterized by being decontextualized on some dimensions while being grounded in the immediate context on others. In this way, parents may scaffold understanding of talk about the there-and-then. We also examined whether caregivers adapt decontextualized verbal input to individual trajectories in language development. We observed 59 parent-child interactions within a decorated room when children were 12 months old, and assessed the children's linguistic development at 12 and 24 months of age. However, we did not find differences in the input directed toward children with different trajectories in language development.

A gestural repertoire of 1- to 2-year-old human children: in search of the ape gestures.

When we compare human gestures to those of other apes, it looks at first like there is nothing much to compare at all. In adult humans, gestures are thought to be a window into the thought processes accompanying language, and sign languages are equal to spoken language with all of its features. Some research firmly emphasises the differences between human gestures and those of other apes; however, the question about whether there are any commonalities is rarely investigated, and has mostly been confined to pointing gestures. The gestural repertoires of nonhuman ape species have been carefully studied and described with regard to their form and function-but similar approaches are much rarer in the study of human gestures. This paper applies the methodology commonly used in the study of nonhuman ape gestures to the gestural communication of human children in their second year of life. We recorded (n = 13) children's gestures in a natural setting with peers and caregivers in Germany and Uganda. Children employed 52 distinct gestures, 46 (89%) of which are present in the chimpanzee repertoire. Like chimpanzees, they used them both singly, and in sequences, and employed individual gestures flexibly towards different goals.

Pupillometry reveals communication-induced object expectations in 12- but not 8-month-old infants.

Several interaction-based and looking-time studies suggest that 1-year-old infants understand the referential nature of deictic gestures. However, these studies have not unequivocally established that referential gestures induce object expectations in infants prior to encountering a referent object, and have thus remained amenable to simpler attentional highlighting interpretations. The current study tested whether nonlinguistic referential communication induces object expectations in infants by using a novel pupil dilation paradigm. In Experiment 1, 12-month-olds watched videos of a protagonist who either pointed communicatively toward an occluder in front of her or remained still. At test, the occluder opened to reveal one of two outcomes: an empty surface or a toy. Results showed that infants' pupils were larger for the unexpected outcome of an empty surface following a point compared to the control condition (an empty surface following no point). These differences were not caused by differences in looking times or directions. In Experiment 2, an attention-directing nonsocial control cue replaced the referential communication. The cue did direct 12-month-olds' attention to the occluder, but it did not induce an object expectation. In Experiment 3, we tested 8-month-olds in the setting of Experiment 1. In contrast to 12-month-olds, 8-month-olds did not reveal object expectations following communication. Findings demonstrate that communicative pointing acts induce object expectations at 12 months of age, but not at 8 months of age, and that these expectations are specific to a referential-communicative as opposed to an attention-directing nonsocial cue.

In Infants' Hands: Identification of Preverbal Infants at Risk for Primary Language Delay.

Early identification of primary language delay is crucial to implement effective prevention programs. Available screening instruments are based on parents' reports and have only insufficient predictive validity. This study employed observational measures of preverbal infants' gestural communication to test its predictive validity for identifying later language delays. Pointing behavior of fifty-nine 12-month-old infants was analyzed and related to their language skills 1 year later. Results confirm predictive validity of preverbal communication for language skills with the hand shape of pointing being superior compared to the underlying motives for pointing (imperative vs. declarative). Twelve-month-olds who pointed only with their open hand but never with their index finger were at risk for primary language delay at 2 years of age.

The Social Reach: 8-Month-Olds Reach for Unobtainable Objects in the Presence of Another Person.

Linguistic communication builds on prelinguistic communicative gestures, but the ontogenetic origins and complexities of these prelinguistic gestures are not well known. The current study tested whether 8-month-olds, who do not yet point communicatively, use instrumental actions for communicative purposes. In two experiments, infants reached for objects when another person was present and when no one else was present; the distance to the objects was varied. When alone, the infants reached for objects within their action boundaries and refrained from reaching for objects out of their action boundaries; thus, they knew about their individual action efficiency. However, when a parent (Experiment 1) or a less familiar person (Experiment 2) sat next to them, the infants selectively increased their reaching for out-of-reach objects. The findings reveal that before they communicate explicitly through pointing gestures, infants use instrumental actions with the apparent expectation that a partner will adopt and complete their goals.

Prelinguistic vocalizations distinguish pointing acts.

The current study investigated whether point-accompanying characteristics, like vocalizations and hand shape, differentiate infants' underlying motives of prelinguistic pointing. We elicited imperative (requestive) and declarative (expressive and informative) pointing acts in experimentally controlled situations, and analyzed accompanying characteristics. Experiment 1 revealed that prosodic characteristics of point-accompanying vocalizations distinguished requestive from both expressive and informative pointing acts, with little differences between the latter two. In addition, requestive points were more often realized with the whole hand than the index finger, while this was the opposite for expressive and informative acts. Experiment 2 replicated Experiment 1, revealing distinct prosodic characteristics for requestive pointing also when the referent was distal and when it had an index-finger shape. Findings reveal that beyond the social context, point-accompanying vocalizations give clues to infants' underlying intentions when pointing.

Differences in the nonverbal requests of great apes and human infants.

This study investigated how great apes and human infants use imperative pointing to request objects. In a series of three experiments (infants, N = 44; apes, N = 12), subjects were given the opportunity to either point to a desired object from a distance or else to approach closer and request it proximally. The apes always approached close to the object, signaling their request through instrumental actions. In contrast, the infants quite often stayed at a distance, directing the experimenters' attention to the desired object through index-finger pointing, even when the object was in the open and they could obtain it by themselves. Findings distinguish 12-month-olds' imperative pointing from ontogenetic and phylogenetic earlier forms of ritualized reaching.

A new online paradigm to measure spontaneous pointing in infants and caregivers.

Index-finger pointing is a milestone in the development of referential communication. Previous research has investigated infants' pointing with a variety of paradigms ranging from parent reports to field observations to experimental settings, suggesting that lab-based semi-natural interactional settings seem especially suited to elicit and measure infant pointing. With the Covid-pandemic the need for a comparable online tool became evident enabling also efficient, low-cost, large-scale, diverse data collection. The current study introduces a remote online paradigm, based on the established live 'decorated-room' paradigm. In Experiment 1, 12-months old infants and their caregivers (N = 24) looked at digitally presented stimuli together while being recorded with their webcam. We coded pointing gestures of infants and caregivers as well as caregivers' responses to infants' pointing. In Experiment 2 (N = 47), we optimized stimuli and investigated influences of stimulus characteristics. We systematically varied the style of depiction, stimulus complexity, motion, and facial stimuli. Main findings were that infants and caregivers pointed spontaneously, with mean behaviors ranging within the benchmarks of previously reported findings of the live decorated-room paradigm. Further, the social setting was preserved as revealed by significant relations between parents' responsive points and infants' pointing frequency. Analyses of stimuli characteristics revealed that infants pointed more to stimuli depicting faces than to other stimuli. The new remote online paradigm proves a useful addition to established paradigms. It offers novel opportunities for simplified assessments, large-scale sampling, and worldwide, diversified data collection.

Language is not necessary for color categories.

The origin of color categories is under debate. Some researchers argue that color categories are linguistically constructed, while others claim they have a pre-linguistic, and possibly even innate, basis. Although there is some evidence that 4-6-month-old infants respond categorically to color, these empirical results have been challenged in recent years. First, it has been claimed that previous demonstrations of color categories in infants may reflect color preferences instead. Second, and more seriously, other labs have reported failing to replicate the basic findings at all. In the current study we used eye-tracking to test 8-month-old infants' categorical perception of a previously attested color boundary (green-blue) and an additional color boundary (blue-purple). Our results show that infants are faster and more accurate at fixating targets when they come from a different color category than when from the same category (even though the chromatic separation sizes were equated). This is the case for both blue-green and blue-purple. Our findings provide independent evidence for the existence of color categories in pre-linguistic infants, and suggest that categorical perception of color can occur without color language.

Sociocultural settings influence the emergence of prelinguistic deictic gestures.

Daily activities of forty-eight 8- to 15-month-olds and their interlocutors were observed to test for the presence and frequency of triadic joint actions and deictic gestures across three different cultures: Yucatec-Mayans (Mexico), Dutch (Netherlands), and Shanghai-Chinese (China). The amount of joint action and deictic gestures to which infants were exposed differed systematically across settings, allowing testing for the role of social-interactional input in the ontogeny of prelinguistic gestures. Infants gestured more and at an earlier age depending on the amount of joint action and gestures infants were exposed to, revealing early prelinguistic sociocultural differences. The study shows that the emergence of basic prelinguistic gestures is socially mediated, suggesting that others' actions structure the ontogeny of human communication from early on.

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.

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.