The origins and evolution of links between word learning and conceptual organization: new evidence from 11‐month‐olds

How do infants map words to their meaning? How do they discover that different types of words (e.g. noun, adjective) refer to different aspects of the same objects (e.g. category, property)? We have proposed that (1) infants begin with a broad expectation that novel open‐class words (both nouns and adjectives) highlight commonalities (both category‐ and property‐based) among objects, and that (2) this initial expectation is subsequently fine‐tuned through linguistic experience. We examine the first part of this proposal, asking whether 11‐month‐old infants can construe the very same set of objects (e.g. four purple animals) either as members of an object category (e.g. animals) or as embodying a salient object property (e.g. four purple things), and whether naming (with count nouns vs. adjectives) differentially influences their construals. Results support the proposal. Infants treated novel nouns and adjectives identically, mapping both types of words to both category‐ and property‐based commonalities among objects.     

Evidence of rapid correlation‐based perceptual category learning by 4‐month‐olds

Young infants are very sensitive to feature distribution information in the environment. However, existing work suggests that they do not make use of correlation information to form certain perceptual categories until at least 7 months of age. We suggest that the failure to use correlation information is a by‐product of familiarization procedures that encourage infants to over encode individual exemplars rather than relations across exemplars. By changing the exemplar presentation regime to one in which exemplars are rapidly (2 s durations) and repeatedly presented we find that 4‐month‐olds can form perceptual categories on the basis of feature correlation information. In addition, this ability emerges rapidly between 114 and 134 days. We argue that the ability to process correlation information is present very early on but that the demonstration of that ability in categorization tasks is mediated by the demands of the task the infant is tested with. Copyright © 2005 John Wiley & Sons, Ltd.     

Causal learning from probabilistic events in 24‐month‐olds: an action measure

How do young children learn about causal structure in an uncertain and variable world? We tested whether they can use observed probabilistic information to solve causal learning problems. In two experiments, 24‐month‐olds observed an adult produce a probabilistic pattern of causal evidence. The toddlers then were given an opportunity to design their own intervention. In Experiment 1, toddlers saw one object bring about an effect with a higher probability than a second object. In Experiment 2, the frequency of the effect was held constant, though its probability differed. After observing the probabilistic evidence, toddlers in both experiments chose to act on the object that was more likely to produce the effect. The results demonstrate that toddlers can learn about cause and effect without trial‐and‐error or linguistic instruction on the task, simply by observing the probabilistic patterns of evidence resulting from the imperfect actions of other social agents. Such observational causal learning from probabilistic displays supports human children's rapid cultural learning.     

Actions speak louder than words: Differences in memory flexibility between monolingual and bilingual 18‐month‐olds

Bilingual infants from 6‐ to 24‐months of age are more likely to generalize, flexibly reproducing actions on novel objects significantly more often than age‐matched monolingual infants are. In the current study, we examine whether the addition of novel verbal labels enhances memory generalization in a perceptually complex imitation task. We hypothesized that labels would provide an additional retrieval cue and aid memory generalization for bilingual infants. Specifically, we hypothesized that bilinguals might be more likely than monolinguals to map multiple perceptual features onto a novel label and therefore show enhanced generalization. Eighty‐seven 18‐month‐old monolingual and bilingual infants were randomly assigned to one of two experimental conditions or a baseline control condition. In the experimental conditions, either no label or a novel label was added during demonstration and again at the beginning of the test session. After a 24‐hr delay, infants were tested with the same stimulus set to test cued recall and with a perceptually different but functionally equivalent stimulus set to test memory generalization. Bilinguals performed significantly above baseline on both cued recall and memory generalization in both experimental conditions, whereas monolinguals performed significantly above baseline only on cued recall in both experimental conditions. These findings show a difference between monolinguals and bilinguals in memory generalization and suggest that generalization differences between groups may arise from visual perceptual processing rather than linguistic processing. A video abstract of this article can be viewed at https://youtu.be/yXB4pM3fF2k     

Imitation from television by 24‐ and 30‐month‐olds

Infants’ imitation of complex actions was examined in three experiments with 24‐ and 30‐month‐olds. In all experiments, an adult modeled a series of actions with novel stimuli and the infant's reproduction of those actions was assessed either immediately or after a 24‐hour delay. Some infants watched the demonstration live, while other infants watched the same demonstration on television from a pre‐recorded videotape. Both 24‐ and 30‐month‐olds imitated actions that had been modeled on television; however, their performance was consistently inferior to that of infants of the same age who watched the demonstration live.     

A perceptual–attentional explanation of gaze following in 3‐ and 6‐month‐olds

Two experiments were conducted with 3‐ and 6‐month‐olds using a standard gaze following procedure with targets to examine the possibility that perceptual–attentional constraints may affect young infants’ gaze following. In Experiment 1, either moving or stationary targets were positioned at 15° from the infants’ midline. In Experiment 2, stationary targets were positioned at either 25° or 40° from the infants’ midline. Gaze following was evaluated with three criteria. Infants made significantly more correct responses to the 15° stationary targets than all other response types combined. When targets were moving or further away, infants made significantly more correct than incorrect responses when they made a turn; however, they did not make significantly more correct responses across all trials. It is argued that the infants’ responses are indicative of perceptual–attention constraints operating where the adult head and eye turn shifts infants’ attention to the side but whether the infants then ‘gaze follow’ depends on the structure of the environment as well as the infants’ ability to disengage attention and initiate saccadic eye movements.     

36‐month‐olds conceal visual and auditory information from others

By three years of age, children are skilled at assessing under which circumstances others can see things. However, nothing is known about whether they can use this knowledge to guide their own deceptive behaviour. Here we investigated 3‐year‐olds’ ability to strategically inhibit or conceal forbidden actions that a nearby adult experimenter could see or hear. In the first experiment, children were more likely to disobey the adult when she did not have visual access to their activities than they were when she was looking at them. In the second experiment, in which the adult could never see the child, children refrained from making noise when engaging in a prohibited action that the adult might hear. These results suggest that by three years of age children use their knowledge of others’ perceptual states to decide whether it is safe to commit a transgression and, moreover, actively conceal perceptual cues that could reveal to others their ongoing transgression.     

The sustained effect of emotional signals on neural processing in 12‐month‐olds

Around the end of the first year of life, infants develop a social referencing ability – using emotional information from others to guide their own behavior. Much research on social referencing has focused on changes in behavior in response to emotional information. The present study was an investigation of the changes in neural responses that underlie social referencing behavior, reflected in event‐related potentials (ERPs). Twenty‐six 12‐month‐olds participated in a single‐session visit in which ERPs were recorded both immediately before and after a behavioral intervention in which infants' caregivers provided positive, negative or neutral information about each of three stimuli (ERP data available for n = 17). After the intervention, infants devoted more neural resources to processing negative versus neutral and positive information, as observed in early and late positive‐going components. Changes in neural responses from the pre‐ to post‐intervention recordings clarify this observation, indicating a sustained response in the negative and positive conditions, and a decrease in the neutral condition, suggesting an attenuation effect in the neutral condition. Further, infants who attended most to the objects in the behavioral intervention showed increased neural responses in the negative condition and decreased responses in the positive condition. Taken together, these findings suggest that infants' neural responses are differentially affected by positive, negative and neutral information. Furthermore, the findings highlight the importance of measuring the change in neural responses to better interpret post‐experience responses.     

Development of the perception of object containment in 9‐ to 16‐month‐olds

In the present study, 9‐, 12‐ and 16‐month‐old infants were familiarized to a block that was repeatedly lowered into a container and lifted from that container again. In the subsequent test phase, the block passed through the container opening either without making contact with the container rim or colliding with the rim in three places but ‘magically’ passing through. In Experiment 1 an opaque black screen was positioned just below the blocks' starting position. In Experiment 2 the screen was put at the height of the container rim and thus occluded the critical arrival phase of the trajectory. Results showed that looking times depended on what infants perceived as happening at the height of the rim and not on what they could have perceived before the block reached the opening, such as the absolute size of the objects. In contrast, older infants looked longer at an obstructed passage of the block into the container, irrespective of the position of the screen.     

Asymmetric interference in 3‐ to 4‐month‐olds' sequential category learning

Three‐ to 4‐month‐old infants show asymmetric exclusivity in the acquisition of cat and dog perceptual categories. The cat perceptual category excludes dog exemplars, but the dog perceptual category does not exclude cat exemplars. We describe a connectionist autoencoder model of perceptual categorization that shows the same asymmetries as infants. The model predicts the presence of asymmetric retroactive interference when infants acquire cat and dog categories sequentially. A subsequent experiment conducted with 3‐ to 4‐month‐olds verifies the predicted pattern of looking time behaviors. We argue that bottom‐up, associative learning systems with distributed representations are appropriate for modeling the operation of short‐term visual memory in early perceptual category learning.     

The ABCs of analogical abilities: Evidence for formal analogical reasoning abilities in 24‐month‐olds

Solving formal analogy problems requires the identification of an initial term and the transformation that occurs between the initial two terms as well as the determination of the final term. Experiment 1 tested 24‐month‐olds' ability to determine final terms when they were shown the initial term and told the transformation that was to occur. Children selected their responses from an array of two principled distracters. The children were able to determine the correct final term when they were given information about the initial term and transformation. Experiment 2 tested 24‐month‐olds' ability to solve final‐term problems, partial analogies, and complete analogies. The children solved all the three types of problems.     

Seeing behind the surface: communicative demonstration boosts category disambiguation in 12‐month‐olds

In their first years, infants acquire an incredible amount of information regarding the objects present in their environment. While often it is not clear what specific information should be prioritized in encoding from the many characteristics of an object, different types of object representations facilitate different types of generalizations. We tested the hypotheses that 1‐year‐old infants distinctively represent familiar objects as exemplars of their kind, and that ostensive communication plays a role in determining kind membership for ambiguous objects. In the training phase of our experiment, infants were exposed to movies displaying an agent sorting objects from two categories (cups and plates) into two locations (left or right). Afterwards, different groups of infants saw either an ostensive or a non‐ostensive demonstration performed by the agent, revealing that a new object that looked like a plate can be transformed into a cup. A third group of infants experienced no demonstration regarding the new object. During test, infants were presented with the ambiguous object in the plate format, and we measured generalization by coding anticipatory looks to the plate or the cup side. While infants looked equally often towards the two sides when the demonstration was non‐ostensive, and more often to the plate side when there was no demonstration, they performed more anticipatory eye movements to the cup side when the demonstration was ostensive. Thus, ostensive demonstration likely highlighted the hidden dispositional properties of the target object as kind‐relevant, guiding infants’ categorization of the foldable cup as a cup, despite it looking like a plate. These results suggest that infants likely encode familiar objects as exemplars of their kind and that ostensive communication can play a crucial role in disambiguating what kind an object belongs to, even when this requires disregarding salient surface features.     

Cerebral blood flow in 5‐ to 8‐month‐olds: Regional tissue maturity is associated with infant affect

Infancy is marked by rapid neural and emotional development. The relation between brain function and emotion in infancy, however, is not well understood. Methods for measuring brain function predominantly rely on the BOLD signal; however, interpretation of the BOLD signal in infancy is challenging because the neuronal‐hemodynamic relation is immature. Regional cerebral blood flow (rCBF) provides a context for the infant BOLD signal and can yield insight into the developmental maturity of brain regions that may support affective behaviors. This study aims to elucidate the relations among rCBF, age, and emotion in infancy. One hundred and seven mothers reported their infants' (infant age M ± SD = 6.14 ± 0.51 months) temperament. A subsample of infants completed MRI scans, 38 of whom produced usable perfusion MRI during natural sleep to quantify rCBF. Mother‐infant dyads completed the repeated Still‐Face Paradigm, from which infant affect reactivity and recovery to stress were quantified. We tested associations of infant age at scan, temperament factor scores, and observed affect reactivity and recovery with voxel‐wise rCBF. Infant age was positively associated with CBF in nearly all voxels, with peaks located in sensory cortices and the ventral prefrontal cortex, supporting the formulation that rCBF is an indicator of tissue maturity. Temperamental Negative Affect and recovery of positive affect following a stressor were positively associated with rCBF in several cortical and subcortical limbic regions, including the orbitofrontal cortex and inferior frontal gyrus. This finding yields insight into the nature of affective neurodevelopment during infancy. Specifically, infants with relatively increased prefrontal cortex maturity may evidence a disposition toward greater negative affect and negative reactivity in their daily lives yet show better recovery of positive affect following a social stressor.     

The role of gaze direction and mutual exclusivity in guiding 24‐month‐olds' word mappings

In these studies, we examined how a default assumption about word meaning, the mutual exclusivity assumption and an intentional cue, gaze direction, interacted to guide 24‐month‐olds' object‐word mappings. In Expt 1, when the experimenter's gaze was consistent with the mutual exclusivity assumption, novel word mappings were facilitated. When the experimenter's eye‐gaze was in conflict with the mutual exclusivity cue, children demonstrated a tendency to rely on the mutual exclusivity assumption rather than follow the experimenter's gaze to map the label to the object. In Expt 2, children relied on the experimenter's gaze direction to successfully map both a first label to a novel object and a second label to a familiar object. Moreover, infants mapped second labels to familiar objects to the same degree that they mapped first labels to novel objects. These findings are discussed with regard to children's use of convergent and divergent cues in indirect word mapping contexts.     

Experience with visual barriers and its effects on subsequent gaze‐following in 12‐ to 13‐month‐olds

Thirty 12‐ to 13‐month‐olds were tested to determine whether they could use the self as an analogy for understanding others' looking. Using a procedure similar to Brooks and Meltzoff (2002) , we examined gaze‐following when the adult's view of a target was occluded by a blindfold (blindfold without training). Some infants received experience with the blindfold's sight‐blocking qualities (blindfold with training). The control was a headband condition. Gaze‐following was highest in the headband condition. Gaze‐following in the headband and blindfold without training conditions, but not the blindfold with training conditions, were significantly greater than zero. These results demonstrate that 12‐ to 13‐month‐olds have some understanding of the looking behaviour of others. Only weak support was found for simulation theories of the development of social cognition.     

Preferential orienting to faces in 4‐month‐olds: analysis of temporal–nasal visual field differences

A two‐process theory of the development of face processing predicted that newborns’ preferential orienting to face‐like patterns would be stronger in the temporal visual field than in the nasal. This prediction was confirmed in a previous study. While it is known that the newborn tendency to orient to face‐like patterns declines around 6 weeks of age, it is not known whether this is due to inhibition by cortical pathways or to the conflicting biases of cortical and subcortical pathways. In the present experiment we repeated the newborn study but with 4‐month‐olds and obtained results which were partially consistent with both the inhibition and the conflicting pathways accounts. We conclude that disappearance of the newborn tendency to orient to face‐like patterns is probably due to multiple factors.     

Joint attention and object learning in 5‐ and 7‐month‐old infants

We examined the effects of joint attention for object learning in 5‐ and 7‐month‐old infants. Infants interacted with an adult social partner who taught them about a novel toy in two conditions. In the Joint Attention condition, the adult spoke about the toy while alternating gaze between the infant and the toy, while in the Object Only condition, the adult looked to the toy and to a spot on the ceiling, but never at the infant. In the test trials following each social interaction, we presented infants with the ‘familiarization’ toy and a novel toy, and monitored looking times to each object. We found that 7‐month‐olds looked significantly longer to the novel toy following the Joint Attention relative to the Object Only condition, while 5‐month‐old infants did not show a significant difference across conditions. We interpret these results to suggest that joint attention facilitated 7‐month‐old infants' encoding of information about the familiarization object. Implications for the ontogeny of infant learning in joint attention contexts are discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Infant gaze following depends on communicative signals: An eye‐tracking study of 5‐ to 7‐month‐olds in Vanuatu

Gaze is considered a crucial component of early communication between an infant and her caregiver. When communicatively addressed, infants respond aptly to others’ gaze by following its direction. However, experience with face‐to‐face contact varies across cultures, begging the question whether infants’ competencies in receiving others’ communicative gaze signals are universal or culturally specific . We used eye‐tracking to assess gaze‐following responses of 5‐ to 7‐month olds in Vanuatu, where face‐to‐face parent–infant interactions are less prevalent than in Western populations. We found that—just like Western 6‐month‐olds studied previously—5‐ to ‐7‐month‐olds living in Vanuatu followed gaze only, when communicatively addressed. That is, if presented gaze shifts were preceded by infant‐directed speech, but not if they were preceded by adult‐directed speech. These results are consistent with the notion that early infant gaze following is tied to infants’ early emerging communicative competencies and rooted in universal mechanisms rather than being dependent on cultural specificities of early socialization.     

Habituation and novelty detection fNIRS brain responses in 5‐ and 8‐month‐old infants: The Gambia and UK

The first 1,000 days of life are a critical window of vulnerability to exposure to socioeconomic and health challenges (i.e. poverty/undernutrition). The Brain Imaging for Global Health (BRIGHT) project has been established to deliver longitudinal measures of brain development from 0 to 24 months in UK and Gambian infants and to assess the impact of early adversity. Here results from the Habituation‐Novelty Detection (HaND) functional near‐infrared spectroscopy (fNIRS) task at 5 and 8 months are presented (N = 62 UK; N = 115 Gambia). In the UK cohort distinct patterns of habituation and recovery of response to novelty are seen, becoming more robust from 5 to 8 months of age. In The Gambia, an attenuated habituation response is evident: a larger number of trials are required before the response sufficiently suppresses relative to the response during the first presented trials. Furthermore, recovery of response to novelty is not evident at 5 or 8 months of age. As this longitudinal study continues in The Gambia, the parallel collection of socioeconomic, caregiving, health and nutrition data will allow us to stratify how individual trajectories of habituation and recovery of response to novelty associate with different risk factors and adaptive mechanisms in greater depth. Given the increasing interest in the use of neuroimaging methods within global neurocognitive developmental studies, this study provides a novel cross‐culturally appropriate paradigm for the study of brain responses associated with attention and learning mechanisms across early development.