Lexical stress and phonetic processing in word learning in 20- to 24-month-old English-learning children

To investigate the interaction between segmental and supra-segmental stress-related information in early word learning, two experiments were conducted with 20- to 24-month-old English-learning children. In an adaptation of the object categorization study designed by Nazzi and Gopnik (2001), children were presented with pairs of novel objects whose labels differed by their initial consonant (Experiment 1) or their medial consonant (Experiment 2). Words were produced with a stress initial (trochaic) or a stress final (iambic) pattern. In both experiments successful word learning was established when the to-be-remembered contrast was embedded in a stressed syllable, but not when embedded in unstressed syllables. This was independent of the overall word pattern, trochaic or iambic, or the location of the phonemic contrast, word-initial or -medial. Results are discussed in light of the use of phonetic information in early lexical acquisition, highlighting the role of lexical stress and ambisyllabicity in early word processing.     

Action production influences 12-month-old infants' attention to others' actions

Recent work implicates a link between action control systems and action understanding. In this study, we investigated the role of the motor system in the development of visual anticipation of others' actions. Twelve-month-olds engaged in behavioral and observation tasks. Containment activity, infants' spontaneous engagement in producing containment actions; and gaze latency, how quickly they shifted gaze to the goal object of another's containment actions, were measured. Findings revealed a positive relationship: infants who received the behavior task first evidenced a strong correlation between their own actions and their subsequent gaze latency of another's actions. Learning over the course of trials was not evident. These findings demonstrate a direct influence of the motor system on online visual attention to others' actions early in development.     

Generalization of learning from picture books to novel test conditions by 18- and 24-month-old children

Researchers know little about whether very young children can recognize objects originally introduced to them in a picture book when they encounter similar looking objects in various real-world contexts. The present studies used an imitation procedure to explore young children's ability to generalize a novel action sequence from a picture book to novel test conditions. The authors found that 18-month-olds imitated the action sequence from a book only when the conditions at testing matched those at encoding; altering the test stimuli or context disrupted imitation (Experiment 1A). In contrast, the 24-month-olds imitated the action sequence with changes to both the test context and stimuli (Experiment 1B). Moreover, although the 24-month-olds exhibited deferred imitation with no changes to the test conditions, they did not defer imitation with changes to the context and stimuli (Experiment 2). Two factors may account for the pattern of results: age-related changes in children's ability to utilize novel retrieval cues as well as their emerging ability to understand the representational nature of pictures.     

Re-enactment of intended acts from a video presentation by 18- and 24-month-old children

We used the Re-enactment of intention paradigm to investigate whether children would re-enact what an adult intended to do in a video presentation as they do when presented with a live demonstration (Meltzoff in Dev Psychol 31(5):838-850, 1995). Unlike the 18-month-old infants studied by Meltzoff (Dev Psychol 31(5):838-850, 1995), the 18- and 24-month-olds in the current study did not frequently imitate unsuccessful goal-directed actions presented in a video model. Children who performed better in the task also tended to share more of their attention with the experimenter during co-viewing of the video. Performance on the Re-enactment of intention task was positively related to categorization score, an independent measure of cognitive functioning.     

Child and maternal correlates of impulse control in 24-month-old children

In two studies, we assessed the ability of 24-month-old children (N = 82) to delay a response to an attractive stimulus on a series of tasks administered by either the child's mother or a female adult stranger. In both studies, delay performance was consistent across tasks, but findings were inconsistent as to the effect on delay performance of a child's gender or the examiner's relationship to the child. Mothers' ratings of their children's personality predicted delay performance; superior performance was associated with low impulsivity, high attention span/persistence, and low sociability. Superior delay performance was also associated with low maternal directiveness as assessed on compliance tasks, and with mothers' encouragement of independence as assessed on a child-rearing attitude questionnaire.     

Development of social perception: a conversation study of 6-, 12- and 36-month-old children

A conversation is made up of visual and auditory signals in a complex flow of events. What is the relative importance of these components for young children's ability to maintain attention on a conversation? In the present set of experiments the visual and auditory signals were disentangled in four filmed events. The visual events were either accompanied by the speech sounds of the conversation or by matched motor sounds and the auditory events by either the natural visual turn taking of the conversation or a matched turn taking of toy trucks. A cornea-reflection technique was used to record the gaze-pattern of subjects while they were looking at the films. Three age groups of typically developing children were studied; 6-month-olds, 1-year-olds and 3-year-olds. The results show that the children are more attracted by the social component of the conversation independent of the kind of sound used. Older children find spoken language more interesting than motor sound. Children look longer at the speaking agent when humans maintain the conversation. The study revealed that children are more attracted to the mouth than to the eyes area. The ability to make more predictive gaze shifts develops gradually over age.     

12- and 18-month-old infants follow gaze to spaces behind barriers

Infants follow the gaze direction of others from the middle of the first year of life. In attempting to determine how infants understand the looking behavior of adults, a number of recent studies have blocked the adult's line of sight in some way (e.g. with a blindfold or with a barrier). In contrast, in the current studies an adult looked behind a barrier which blocked the child's line of sight. Using two different control conditions and several different barrier types, 12- and 18-month-old infants locomoted a short distance in order to gain the proper viewing angle to follow an experimenter's gaze to locations behind barriers. These results demonstrate that, contra Butterworth, even 12-month-old infants can follow gaze to locations outside of their current field of view. They also add to growing evidence that 12-month-olds have some understanding of the looking behaviors of others as an act of seeing.     

The adaptation to sensory information in the production of bimanual movement patterns

Bimanual in-phase and anti-phase patterns were performed in the transverse plane under optimal and degraded proprioceptive conditions, i.e., without and with tendon vibration. Moreover, proprioceptive information was changed midway into each trial to examine on-line reorganization. In addition to the proprioceptive perturbation, the availability of visual information was manipulated to study to which degree sensory information from different modalities interact. Movement patterns performed under identical sensory conditions were compared, i.e., the first 15 s (control) and the 15 s following a change in afferent input (transfer). In the control and transfer conditions, movements with vibrations were less accurate than those without vibrations indicating the influence of optimal proprioceptive information in the calibration and recalibration of intrinsic bimanual movement patterns. Furthermore, pattern stability was affected by the nature of the transfer condition. This indicated that the degree of fluctuations in a sensory transfer situation depended upon the quality of the proprioceptive information experienced in the initial conditions. The influence of visual information was not without importance, although the nature of the coordination mode must be taken into account. In the control conditions, in-phase movements were less stable when vision was absent, whereas anti-phase movements were more stable when vision was not present. This observation was made independent of the available proprioceptive information revealing differences in visual guidance between both coordination modes. In the transfer conditions, pattern stability was similar during the vision and no-vision conditions suggesting a limited influence of visual information in the recalibration process.     

Disorientation inhibits landmark use in 12-18-month-old infants

Recent research has indicated that, particularly under conditions of inertial disorientation, mammals may be sensitive to landmark configuration geometry at the expense of individual featural information when locating hidden goals. The current study sought to establish whether landmark use could be demonstrated in 12-18-month-old infants with and without a disorientation procedure, and with geometrically ambiguous landmark configurations. A peekaboo paradigm was employed in which infants learned to anticipate a peekaboo event after a cue from two locations within a circular arena, followed by a test trial from a novel position in which no peekaboo occurred after the cue. In all conditions, an isosceles triangle arrangement of landmarks was used, with peekaboo occurring between the landmarks of one of the two equal "sides", thus being geometrically ambiguous. In two conditions, the landmarks were distinctive, and in two further conditions, they were identical. In one of the distinctive conditions and one of the identical landmark conditions, infants underwent a disorientation procedure in between training and test trials. Only oriented infants with distinctive landmarks were successful in test trials, thus suggesting that infants are able to use the individual features of landmarks to locate a goal, but can only do so if oriented.     

Asymmetrical responding to male versus female other-race categories in 9- to 12-month-old infants

Faces can be categorized along various dimensions including gender or race, an ability developing in infancy. Infant categorization studies have focused on facial attributes in isolation, but the interaction between these attributes remains poorly understood. Experiment 1 examined gender categorization of other-race faces in 9- and 12-month-old White infants. Nine- and 12-month-olds were familiarized with Asian male or female faces, and tested with a novel exemplar from the familiarized category paired with a novel exemplar from a novel category. Both age groups showed novel category preferences for novel Asian female faces after familiarization with Asian male faces, but showed no novel category preference for novel Asian male faces after familiarization with Asian female faces. This categorization asymmetry was not due to a spontaneous preference hindering novel category reaction (Experiment 2), and both age groups displayed difficulty discriminating among male, but not female, other-race faces (Experiment 3). These results indicate that category formation for male other-race faces is mediated by categorical perception. Overall, the findings suggest that even by 12 months of age, infants are not fully able to form gender category representations of other-race faces, responding categorically to male, but not female, other-race faces.     

An examination of spontaneous pointing in 20- to 50-month-old children.

Occurrences of spontaneous pointing in 20-, 30-, 40-, and 50-mo.-old children were observed during the children's indoor or outdoor free-play periods. Observers recorded the sex of the pointer, the behavioral pattern observed, the reason for the point, the response of the adult, and the distance of the child from the adult at the time of a point. Analysis indicated a significant dip in the rate of pointing among the 30-mo.-olds while the 20- and 50-mo.-olds were observed to point most often. With the exception of the 30-mo.-olds, pointing was significantly more likely to be observed in boys. For all age groups, the point was used primarily to name. After 20 months adults were significantly less likely to respond to the point, and when they did respond they were more likely to name or demonstrate irrespective of the apparent reason for the child's point. Finally, the probability of adults' response appeared to be unrelated to the distance from the child to the adult, and further, the likelihood of an adult's response appeared to exert little influence on the rate of pointing. The results suggest that pointing may be an expressive act that can be used as a communicative gesture, but there was little evidence that any of these age groups were using the point as a ritualized gesture, that is, as an action conventionalized within the context of social interaction.     

Foetal testosterone and vocabulary size in 18- and 24-month-old infants

Amniotic fluid, obtained from 87 pregnant women for routine amniocentesis, was analysed for foetal testosterone (FT) level. Their infants (40 girls and 47 boys) were followed up 18 and 24 months after birth and their vocabulary size was assessed. Girls were found to have a significantly larger vocabulary than boys at both ages. This replicates previous findings of a female advantage in language ability, but reveals this sex difference at the earliest point of development. Additionally, FT was an inverse predictor of vocabulary size when data from both sexes was examined together, but not within sex. The lack of a significant correlation between FT and vocabulary within each sex may reflect the relatively small sample size. However, the significant correlation between FT and vocabulary when the sexes were combined suggests FT might be involved in shaping the neural mechanisms underlying communicative development.     

A cross-sequential assessment of the occurrences of pointing in 3- to 12-month-old human infants

This study presents evidence that a developmental continuity exists between early forms of “pointing” and the later, mature form of social gesturing seen during the latter half of the first year of life. Sixteen infants and their mothers were observed in two different conditions of face-to-face interaction during the first year of life (“mother-alone” and “mother-toy”). The rate (adjusted frequency), proportion (percent of total time), and mean duration of pointing were derived from each infant's videotaped sessions. In addition, the degree of co-occurrence between pointing and selected infant and maternal behaviors was assessed. Significant differences by interactional condition and by hand (right or left) were noted for the proportion and mean duration of pointing; however, none of the tests of co-occurrence were significant. Although there was little indication of a functional continuity between early and later appearing forms of pointing, the general findings indicated a potential morphological continuity that had previously been overlooked. It is suggested that a different developmental approach may be necessary to explain the changes in the structural and functional components of this gesture during the first year of life.     

Functions of the pointing gesture in mothers and their 12 to 36-month-old children during everyday activities

This study longitudinally examined the production of pointing in four Spanish 1-year-old and four Spanish 2-year-old children in interactive situations with their mothers at home over the course of one year. Three aspects were analyzed: a) the functions of the pointing gesture, their accurate comprehension by the interlocutor (mother or child), and their order of emergence in the child; b) whether or not there were differences in the production of pointing according to who initiated the interaction; and c) whether maternal and child speech were related to maternal and child pointing production. The results showed that the pointing function of showing is the most frequent for both children and mothers from groups 1 and 2, and the first to emerge followed by the informing, requesting object, requesting action, and requesting cooperation functions. The accuracy with which these intentions were comprehended was found to be very high for both mother and child. Pointing production was greater when the speaker initiated the interaction than when the other person did, indicating that gestures follow the turn-taking system. Finally, the production of pointing to showing in children and mothers was found to be related to maternal and child speech, while pointing to request cooperation triggered the process of joint activity between mother and child.     

Understanding deceptive intentions behind pointing gestures in 12-15-month-old infants

We examined the comprehension of deceptive intentions revealed in searching task in infancy, on the theoretical basis of natural pedagogy and epistemic trust. The main findings showed that 12-15-month-old infants are able to discriminate the reliable and the deceptive actions of adults, but they do not generalize their previous experience in connection with a novel person, who is treated as a new reliable source of information.     

Attention demands influence 10- and 12-month-old infants' perseverative behavior

The present study examined the role of attentional demand on infants' perseverative behavior in a noncommunicative looking version of an A-not-B task. The research aimed at clarifying age-related improvements in the attention process that presumably underlies the development of cognitive control. In a between-subjects design, forty 10-month-olds and forty 12-month-olds were assigned to either a distractor or a no-distractor condition as a means of testing the role of attentional load. The authors used an eye tracker to record infants' looking behavior while they anticipated the reappearance of the target of interest as well as continuously throughout the task. The data demonstrated that 10-month-olds show more perseverative looking than do 12-month-olds and that increased attentional demand leads to more perseverative looking. Correct anticipation, however, was not affected by age or distraction. The results also failed to show that 12-month-olds are better than 10-month-olds at handling the increased attentional demand introduced in the distractor condition, in that the effect of the distractor was not larger for the younger infants. Our results are in line with the theoretical view of cognitive control as dependent on a limited attentional resource, which can explain perseverative behaviors in different tasks and at different ages.     

Attending to the non-preferred hand improves bimanual coordination in children

The effect of attentional focus in bimanual coordination was investigated from a developmental perspective by examining performance of right- and left-handed children, 5-8-years and 9-12-years old, on bimanual reciprocal tapping tasks. Attentional focus was either specified, by asking the children to attend to the preferred or to the non-preferred hand, or unspecified for the execution of the tasks. When attention was oriented to the non-preferred hand we found a reduced movement time and a lower frequency of errors. Performance differences for handedness and age-groups were observed when the children were oriented to attend to the preferred hand or when there was no instruction regarding attention. These differences in performance were eliminated when attention was oriented to the non-preferred hand.     

Bimodal familiarization re-sensitizes 12-month-old infants to other-race faces

Perceptual narrowing in the domain of face perception typically begins to reduce infants’ sensitivity to differences distinguishing other-race faces from approximately 6 months of age. The present study investigated whether it is possible to re-sensitize Caucasian 12-month-old infants to other-race Asian faces through statistical learning by familiarizing them with different statistical distributions of these faces. The familiarization faces were created by generating a morphed continuum from one Asian face identity to another. In the unimodal condition, infants were familiarized with a frequency distribution wherein they saw the midpoint face of the morphed continuum the most frequently. In the bimodal condition, infants were familiarized with a frequency distribution wherein they saw faces closer to the endpoints of the morphed continuum the most frequently. After familiarization, infants were tested on their discrimination of the two original Asian faces. The infants’ looking times during the test indicated that infants in the bimodal condition could discriminate between the two faces, while infants in the unimodal condition could not. These findings therefore suggest that 12-month-old Caucasian infants could be re-sensitized to Asian faces by familiarizing them with a bimodal frequency distribution of such faces.     

Stability of deferred imitation in 12- to 18-month-old infants: A closer look into developmental dynamics

Deferred imitation is used to assess declarative memory in infants. Although a lot of studies show that infants from 6 months onwards are able to re-enact actions following a delay, only a few studies describe early declarative memory longitudinally. From a variable-centred approach, these studies found a modest relationship between measurement occasions that increases with age. However, no studies have analysed the differential aspect of memory development from a person-centred perspective. The present study analyses memory stabilities both from a variable-centred and person-centred approach within a sample of N = 87 infants of a 2-wave longitudinal design (12- and 18-month-olds). From a variable-centred perspective, the results indicate that, first, there was a significant increase in infants' memory performance and, second, that although reliable, the stability of infants' memory performance was relatively low. From a person-centred perspective two vs. three groups of infants were differentiated showing different developmental growth trajectories and stability correlations but no differences in language, cognitive and motor development. The implications of those results in terms of further test development are discussed. Furthermore, important methodological expansions for the analysis of infants' memory data are presented and discussed.