Fifteen-month-old infants attend to shape over other perceptual properties in an induction task

This study examined whether infants privilege shape over other perceptual properties when making inferences about the shared properties of novel objects. Forty-six 15-month-olds were presented with novel target objects that possessed a nonobvious property, followed by test objects that varied in shape, color, or texture relative to the target. Infants generalized the nonobvious property to test objects that were highly similar in shape, but not to objects that shared the same color or texture. These results demonstrate that infants’ attention to shape is not specific to lexical contexts and is present at the early stages of productive language development. The implications of these findings for debates about children's shape bias, in particular, and the nature of infants’ categories more generally, are discussed.     

Perception of tones by infants learning a non-tone language

This article examines the perception of tones by non-tone-language-learning (non-tone-learning) infants between 5 and 18 months in a study that reveals infants’ initial sensitivity to tonal contrasts, deterioration yet plasticity of tonal sensitivity at the end of the first year, and a perceptual rebound in the second year. Dutch infants in five age groups were tested on their ability to discriminate a tonal contrast of Mandarin Chinese as well as a contracted tonal contrast. Infants are able to discriminate tonal contrasts at 5–6 months, and their tonal sensitivity deteriorates at around 9 months. However, the sensitivity rebound sat 17–18 months. Non-tone-learning infants’ tonal perception is elastic, as is shown by the influence of acoustic salience and distributional learning: (1) a salient contrast may remain discriminable throughout infancy whereas a less salient one does not; (2) a bimodal distribution in tonal exposure increases non-tone-learning infants’ discrimination ability during the trough in sensitivity to tonal contrasts at 11–12 months. These novel findings reveal non-tone-learning infants’ U-shaped pattern in tone perception, and display their perceptual flexibility.     

Infants' attribution of a goal to a morphologically unfamiliar agent

How do infants identify the psychological actors in their environments? Three groups of 12‐month‐old infants were tested for their willingness to encode a simple approach behavior as goal‐directed as a function of whether it was performed by (1) a human hand, (2) a morphologically unfamiliar green object that interacted with a confederate and behaved intentionally, or (3) the same unfamiliar green object that behaved in a matched, but apparently random manner. Using a visual habituation technique, only infants in the first two conditions were found to encode the approach behavior as goal‐directed. Thus infants appear able to attribute goals to non‐human, even unfamiliar agents. These results imply that by the end of the first year of life infants have a broad notion of what counts as an agent that cannot easily be reduced to humans, objects that are perceptually similar to humans, or objects that display self‐propulsion.     

Infants prefer to imitate a reliable person

Research has shown that preschoolers prefer to learn from individuals who are a reliable source of information. The current study examined whether the past reliability of a person's emotional signals influences infants’ willingness to imitate that person. An emotional referencing task was first administered to infants in order to demonstrate the experimenter's credibility or lack thereof. Next, infants in both conditions watched as the same experimenter turned on a touch light using her forehead. Infants were then given the opportunity to reproduce this novel action. As expected, infants in the unreliable condition developed the expectation that the person's emotional cues were misleading. Thus, these infants were subsequently more likely to use their hands than their foreheads when attempting to turn on the light. In contrast, infants in the reliable group were more likely to imitate the experimenter's action using their foreheads. These results suggest that the reliability of the model influences infants’ imitation.     

Fourteen-month-old infants copy an action style accompanied by social-emotional cues

Human adults exaggerate their actions and facial expressions when interacting with infants. These infant-directed modifications highlight certain aspects of action sequences and attract infants’ attention. This study investigated whether social-emotional aspects of infant-directed modifications, such as smiling, eye contact, and onomatopoeic vocalization, influence infants’ copying of another's action, especially action style, during the process of achieving an outcome. In Study 1, 14-month-old infants (n = 22) saw an experimenter demonstrate goal-directed actions in an exaggerated manner. Either the style or the end state of the actions was accompanied by social-emotional cues from the experimenter. Infants copied the style of the action more often when social-emotional cues accompanied the style than when they accompanied the end state. In Study 2, a different group of 14-month-old infants (n = 22) watched the same exaggerated actions as in Study 1, except that either the style or the end state was accompanied by a physical sound instead of social-emotional cues. The infants copied the end state consistently more often than the style. Taken together, these two studies showed that accompanying social-emotional cues provided by a demonstrator, but not accompanying physical sound, increased infants’ copying of action style. These findings suggest that social-emotional cues facilitate efficient social learning through the adult–infant interaction.     

Socially guided attention influences infants’ communicative behavior

For effective prelinguistic communication, infants must be able to direct their attention, vocalizations, and nonverbal gestures in social interactions. The purpose of our study was to examine how different styles of caregiver responses influenced infant attentional and communicative behavior in social interactions, based on prior studies that have shown influences of responsiveness on attention, language and cognitive outcomes. Infants were exposed to redirective and sensitive behavior systematically using an ABA design to examine real-time changes in infants’ behavior as a function of caregiver responses. During the two baseline “A” periods, caregivers were instructed to play as they would at home. During the social response “B” period, caregivers were instructed to respond sensitively to infants’ behavior on one visit and redirectively on the other visit. Results demonstrated that when caregivers behaved redirectively, infants shifted their attention more frequently and decreased the duration of their visual attention. Caregiver responses also resulted in changes in vocal and gesture production. Infants decreased their production of caregiver-directed vocalizations, gestures, and gesture-vocal combinations during in the redirective condition. Results suggest that caregiver sensitive responding to infants’ attentional focus may be one influence on infants’ attentional and prelinguistic communicative behavior.     

Relations between 18-month-olds’ gaze pattern and target action performance: A deferred imitation study with eye tracking

Deferred imitation studies are used to assess infants’ declarative memory performance. These studies have found that deferred imitation performance improves with age, which is usually attributed to advancing memory capabilities. Imitation studies, however, are also used to assess infants’ action understanding. In this second research program it has been observed that infants around the age of one year imitate selectively, i.e., they imitate certain kinds of target actions and omit others. In contrast to this, two-year-olds usually imitate the model's exact actions. 18-month-olds imitate more exactly than one-year-olds, but more selectively than two-year-olds, a fact which makes this age group especially interesting, since the processes underlying selective vs. exact imitation are largely debated. The question, for example, if selective attention to certain kinds of target actions accounts for preferential imitation of these actions in young infants is still open. Additionally, relations between memory capabilities and selective imitation processes, as well as their role in shaping 18-month-olds’ neither completely selective, nor completely exact imitation have not been thoroughly investigated yet. The present study, therefore, assessed 18-month-olds’ gaze toward two types of actions (functional vs. arbitrary target actions) and the model's face during target action demonstration, as well as infants’ deferred imitation performance. Although infants’ fixation times to functional target actions were not longer than to arbitrary target actions, they imitated the functional target actions more frequently than the arbitrary ones. This suggests that selective imitation does not rely on selective gaze toward functional target actions during the demonstration phase. In addition, a post hoc analysis of interindividual differences suggested that infants’ attention to the model's social-communicative cues might play an important role in exact imitation, meaning the imitation of both functional and arbitrary target actions.     

Individual differences in social, cognitive, and morphological aspects of infant pointing

Little is known about the origins of the pointing gesture. We sought to gain insight into its emergence by investigating individual differences in the pointing of 12-month-old infants in two ways. First, we looked at differences in the communicative and interactional uses of pointing and asked how different hand shapes relate to point frequency, accompanying vocalizations, and mothers’ pointing. Second, we looked at differences in social-cognitive skills of point comprehension and imitation and tested whether these were related to infants’ own pointing. Infants’ and mothers’ spontaneous pointing correlated with one another, as did infants’ point production and comprehension. In particular, infants’ index-finger pointing had a profile different from simple whole-hand pointing. It was more frequent, it was more often accompanied by vocalizations, and it correlated more strongly with comprehension of pointing (especially to occluded referents). We conclude that whole-hand and index-finger pointing differ qualitatively and suggest that it is index-finger pointing that first embodies infants’ understanding of communicative intentions.     

Common ground on object use associates with caregivers’ gesturese

Caregivers modify their communication when interacting with infants, and these modifications have been related to children's language development. However, the factors influencing caregivers’ modification of gestures are understudied. This study examined whether infants’ object knowledge, considered as common ground shared with the caregiver, relates to caregivers’ gesturese. Six caregiver-infant dyads were videotaped every two months for 15 min in their homes, from child age 8-to-16 months, while they played with two separate objects (i.e. toys). Results indicated that the changes in infants’ object knowledge were paralleled by associated changes in caregivers’ gestures: parents increased both the amount and the complexity of their gestures.     

Factors influencing infants’ ability to update object representations in memory

Remembering persisting objects over occlusion is critical to representing a stable environment. Infants remember hidden objects at multiple locations and can update their representation of a hidden array when an object is added or subtracted. However, the factors influencing these updating abilities have received little systematic exploration. Here we examined the flexibility of infants’ ability to update object representations. We tested 11-month-olds in a looking-time task in which objects were added to or subtracted from two hidden arrays. Across five experiments, infants successfully updated their representations of hidden arrays when the updating occurred successively at one array before beginning at the other. But when updating required alternating between two arrays, infants failed. However, simply connecting the two arrays with a thin strip of foam-core led infants to succeed. Our results suggest that infants’ construal of an event strongly affects their ability to update memory representations of hidden objects. When construing an event as containing multiple updates to the same array, infants succeed, but when construing the event as requiring the revisiting and updating of previously attended arrays, infants fail.     

Categorization of two-dimensional and three-dimensional stimuli by 18-month-old infants

In two experiments, 18-month-old infants’ categorization of 3D replicas and 2D photographs of the same animals and vehicles were compared to explore infants’ flexibility in categorization across different object representations. Using a sequential touching procedure, infants completed one superordinate and two basic-level categorization tasks with 3D replicas, 2D cut out photographs, or 2D images on photo cubes (“2D cubes”). For superordinate sets, 3D replicas elicited longer mean run lengths than 2D cut outs, and 3D replicas elicited equivalent mean run lengths as 2D cubes. For basic-level sets, infants categorized high-contrast animal sets when presented with 3D replicas, but they failed to categorize any of the 2D photograph sets. Categorization processes appear to differ for 3D and 2D stimuli, and infants’ discovery of object properties over time while manipulating objects may facilitate categorization, as least at the superordinate level. These findings are discussed in the context of infants’ representation abilities and the integration of perception and action.     

Screen media and language development in infants and toddlers: An ecological perspective

The abilities to understand and use language represent two of the most important developmental competencies that children must master during the first 3 years of life. Over the past decade, screen media content directed at infants and toddlers has dramatically increased. As a result, infants’ and toddlers’ time spent with media has also notably increased (i.e., 1–2 h per day). At present, there is limited empirical knowledge regarding how screen media influence infants’ and toddlers’ language development. In this review, we contend that infants and toddlers are capable of learning from screen media. This learning is dependent upon the confluence of three distinct but interrelated factors: attributes of the child; characteristics of the screen media stimuli; and the varied environmental contexts surrounding the child’s screen media use. To examine these interrelated factors, we have adopted an ecological framework in which a young child’s language skills develop from the reciprocal transactions between the child and the broader environmental contexts in which a child is situated or operates. Screen media effects are dependent on the degree to which media content resembles infants’ and toddlers’ real-life experiences including the use of simple stories and familiar objects or routines. Repeated exposure also helps infants and toddlers learn both the format and the content of screen media and can even ameliorate negative effects associated with viewing particular content. Finally, the presence of a competent co-viewer appears to boost babies’ language learning from screen media, much like the ways these processes facilitate learning in live scenarios.     

Linking sounds to meanings: Infant statistical learning in a natural language

The processes of infant word segmentation and infant word learning have largely been studied separately. However, the ease with which potential word forms are segmented from fluent speech seems likely to influence subsequent mappings between words and their referents. To explore this process, we tested the link between the statistical coherence of sequences presented in fluent speech and infants’ subsequent use of those sequences as labels for novel objects. Notably, the materials were drawn from a natural language unfamiliar to the infants (Italian). The results of three experiments suggest that there is a close relationship between the statistics of the speech stream and subsequent mapping of labels to referents. Mapping was facilitated when the labels contained high transitional probabilities in the forward and/or backward direction (Experiment 1). When no transitional probability information was available (Experiment 2), or when the internal transitional probabilities of the labels were low in both directions (Experiment 3), infants failed to link the labels to their referents. Word learning appears to be strongly influenced by infants’ prior experience with the distribution of sounds that make up words in natural languages.     

Comparison of active and purely visual performance in a multiple-string means-end task in infants

The aim of the present study was to understand what factors influence infants’ problem-solving behaviours on the multiple-string task. The main question focused on why infants usually solve the single string-pulling task at 12 months at the latest, whereas most 16-month-old infants still cannot solve the task when several strings are presented, only one of which is attached to the desired object. We investigated whether this difficulty is related to infants’ ability to inhibit their spontaneous immediate actions by comparing active and purely visual performance in this task. During the first part of the experiment, we assessed the ability of infants aged 16–20 months to solve the multiple-string task. The infants were then divided into three groups based on performance (a “failure” group, an “intermediate” group, and a “success” group). The results of this action task suggest that there were differences in infants’ performance according to their level of inhibitory control of their preferred hand. In the second part of the experiment, the three groups’ predictive looking strategies were compared when seeing an adult performing the task. We found that only infants who successfully performed the action task also visually anticipated which string the adult had to pull in the visual task. Our results suggests that inhibitory control was not the only factor influencing infants’ performance on the task. Furthermore, the data support the direct matching hypothesis (Rizzolatti and Fadiga, 2005), according to which infants need to be able to perform actions themselves before being able to anticipate similar actions performed by others.     

Ten- and twelve-month-olds' visual anticipation of orientation and size during grasping

The anticipation of two object dimensions during grasping was investigated in 10- and 12-month-olds. We presented objects varying in both orientation and size and analyzed infants’ anticipatory hand configurations. We found in Experiment 1 that nearly all of the 12-month-olds (94%), but less than half of the 10-month-olds (40%), anticipated both dimensions before touching the object. Experiment 2 ruled out the possibility that this behavior resulted from the infants’ inability to anticipate the size of the stimuli. Thus, integrating two object dimensions during reaching seems to be difficult for 10-month-olds. In addition, we found a sequential adjustment when two dimensions were considered: Infants first adjusted the orientation and then the size. The implications of our findings concerning the planning and execution of grasping movements are discussed.     

Tolerance of geometric distortions in infant's face recognition

The aim of the current study is to reveal the effect of global linear transformations (shearing, horizontal stretching, and vertical stretching) on the recognition of familiar faces (e.g., a mother's face) in 6- to 7-month-old infants. In this experiment, we applied the global linear transformations to both the infants’ own mother's face and to a stranger's face, and we tested infants’ preference between these faces. We found that only 7-month-old infants maintained preference for their own mother's face during the presentation of vertical stretching, while the preference for the mother's face disappeared during the presentation of shearing or horizontal stretching. These findings suggest that 7-month-old infants might not recognize faces based on calculating the absolute distance between facial features, and that the vertical dimension of facial features might be more related to infants’ face recognition rather than the horizontal dimension.     

Infant's perception of goal-directed actions performed by a mechanical device

The present work investigated whether by the end of the first year, infants interpret actions performed by a mechanical device as goal-directed and why they would do so. Using a modified version of the Woodward (1998) habituation paradigm, 9- and 12-month-old infants were tested in a condition in which they saw a mechanical claw performing an action (Study 1). When infants viewed the claw grasping and transporting objects to the back of a stage, 12-month-old but not 9-month-old infants interpreted the action as goal-directed. In Study 2, 9-month-olds received prior to habituation an information phase showing infants how a human held and operated the claw. This enrichment of infants’ knowledge enabled 9-month-old infants to interpret the action display as goal-directed. The role of the developing means-end understanding and tool-use for infants’ interpretation of actions performed by a mechanical device is discussed.     

Development of infant reaching behaviors: Kinematic changes in touching and hitting

This longitudinal study investigated the development of reaching in typical infants, from age 4 to 8 months, and described the pattern of hand kinematics underlying changes in the characteristics of infants’ actions while reaching for a target. Thirteen infants were followed biweekly. Two reaching behaviors emerged during the infants’ free interactions with the target, touching and hitting. Changes over time were documented for the number of movement units, straightness index, distance, peak velocity and time to peak velocity of the hand for touches and hits. We observed increases in the numbers of touches and hits and changes in hand kinematics over time; the distance traveled by the hand was greater for hitting compared to touching. These kinematic changes were specific to the movement patterns that infants adopted to reach to the target.     

Not just playing around: Infants’ behaviors with objects reflect ability,constraints, and object properties

This study describes infants’ behaviors with objects in relation to age, body position, and object properties. Object behaviors were assessed longitudinally in 22 healthy infants supine, prone, and sitting from birth through 2 years. Results reveal: (1) infants learn to become intense and sophisticated explorers within the first 6 months of life; (2) young infants dynamically and rapidly shift among a variety of behavioral combinations to gather information; (3) behaviors on objects develop along different trajectories so that behavioral profiles vary across time; (4) object behaviors are generally similar in supine and sitting but diminished in prone; and (5) infants begin matching certain behaviors to object properties as newborns. These data demonstrate how infants learn to match their emerging behaviors with changing positional constraints and object affordances.     

Is early word-form processing stress-full? How natural variability supports recognition

In a series of studies, we examined how mothers naturally stress words across multiple mentions in speech to their infants and how this marking influences infants’ recognition of words in fluent speech. We first collected samples of mothers’ infant-directed speech using a technique that induced multiple repetitions of target words. Acoustic analyses revealed that mothers systematically alternated between emphatic and nonemphatic stress when talking to their infants. Using the headturn preference procedure, we then tested 7.5-month-old infants on their ability to detect familiarized bisyllabic words in fluent speech. Stress of target words (emphatic and nonemphatic) was systematically varied across familiarization and recognition phases of four experiments. Results indicated that, although infants generally prefer listening to words produced with emphatic stress, recognition was enhanced when the degree of emphatic stress at familiarization matched the degree of emphatic stress at recognition.