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.     

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.     

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.     

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.     

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.     

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.     

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.     

Fear,attachment and affiliation: The interaction of functional systems in 8- and 12-month-old infants

In this research fear of strangers has been analysed as it interacts with attachment and affiliation, and in relation to developmental level, in conditions most similar to the natural situations where encounters with unfamiliar persons take place. A total of 30 infants and their mothers participated. The children were divided into two groups (8-9 and 11-12 months). Each infant was approached by two females, who, in turn, produced either of two natural sequences. Our results allowed us to confirm the universality of fear and its coexistence and interaction with attachment and affiliation. As far as the role that developmental level plays, it was noted that in the 12-month-old infants fear reactions were more intense than in the younger ones. Furthermore, the attachment system was more activated in the older group in the intrusive episodes, but when the threatening nature of the situation decreased, attachment was activated less in the 12-month-old group. Another difference was related to control resources. While in the younger infants we observed a tendency to control their own emotional state, the 12-month-old infants tried to gain control over the stranger. These results were interpreted by considering the adaptative value of an increase with age of the capacity to evaluate a situation's threat value, of attachment security, and of behavioural resources permitting some control over the stranger's behaviour.     

Perceptual transparency in 3- to 4-month-old infants

We examined perceptual transparency in infants. In a previous study, Johnson and Aslin (2000 Developmental Psychology 36 808 - 816) found that 4-month-olds could perceive transparency in a moving chromatic display, but not in an achromatic display. In this study, we further examined perceptual transparency in infants using a static achromatic display. Considering the development of figural organisation and contrast sensitivity, we assumed that 3- to 4-month-olds would perceive transparency even in a static achromatic display. We created a transparency and a non-transparent display composed of a partially overlapping circle and square, by switching the colours. Infants aged 3 to 4 months (n = 24) were familiarised with the transparency display (experiment 1) or with the non-transparent display (experiment 2). Then, they were confronted with a uniform colour and a two-colour figure. Infants showed novelty preference for the two-colour figure after they had been familiarised with the transparency display (experiment 1), but not after they had been familiarised with the non-transparent display (experiment 2). These results suggest that 3- to 4-month-old infants can perceive transparency in a static achromatic display.     

Labeling guides object individuation in 12-month-old infants

A new manual search method was used to investigate the impact of naming on object individuation in 12-month-old infants. In Experiment 1, on a two-word trial, an experimenter looked into a box while the infant was watching and provided two labels (e.g., "Look, a fep!" and "Look, a wug!"). On a one-word trial, the experimenter instead repeated the same label (e.g., "Look, a zav!"). After the infant retrieved one object from the box, subsequent search behavior was recorded. Infants searched more persistently (i.e., for a longer duration) after hearing two labels than one, suggesting that hearing two labels led the infants to expect two objects inside the box. In Experiment 2, infants' search behavior did not differ depending on whether they heard one or two emotional expressions, suggesting that the facilitation effect observed in Experiment 1 may be specific to linguistic expressions. Thus, we provide the first evidence that infants as young as 12 months are able to use intentional and referential cues to guide their object representations. These findings also suggest that a rudimentary version of the mutual-exclusivity constraint may be functional by the end of the first year.     

Social looking,social referencing and humor perception in 6- and-12-month-old infants

Social referencing refers to infants’ use of caregivers as emotional referents in ambiguous situations (Walden, 1993). Studies of social referencing typically require ambulation, thereby over-looking younger, non-ambulatory infants (i.e., ≤8-months) and resulting in a widespread assumption that young infants do not employ this strategy. Using a novel approach that does not require mobility, we found that when parents provided unsolicited affective cues during an ambiguous-absurd (i.e., humorous) event, 6-month-olds employ one component of social referencing, social looking Additionally, 6-month-olds who did not laugh at the event were significantly more likely to look toward parents than their counterparts who found the event funny. Sequential analyses revealed that, following a reference to a smiling parent, 6-month olds were more likely to smile at the parent, but by 12 months were more likely to smile at the event suggesting that older infants are influenced by parental affect in humorous situations. The developmental implications of these findings are discussed, as well as the usefulness of studying humor for understanding important developmental phenomena.     

Syllabic pitch perception in 2- to 3-month-old infants

The pitch patterns present in speech addressed to infants may play an important role in perceptual processing by infants. In this study, the high-amplitude sucking procedure was used to assess discrimination by 2- to 3-month-old infants of rising versus falling pitch patterns in 400-msec synthetic [ra] and [la] tokens. The syllables’ intonation contour was modeled on infant-directed speech, and covered a range characteristic of an adult female speaker (180–300 Hz). Group data indicated that the 2- to 3-month-old infants discriminated the pitch contour for both stimuli. Results are discussed with reference to previous studies of syllabic pitch perception.     

Secret agents: inferences about hidden causes by 10- and 12-month-old infants

Considerable evidence indicates that preverbal infants expect that only physical contact can cause an inanimate object to move. However, very few studies have investigated infants' expectations about the source of causal power. In three experiments, we found that (a) 10- and 12-month-old infants expect a human hand, and not an inanimate object, to be the primary cause of an inanimate object's motion; (b) infants' expectations can lead them to infer a hidden causal agent without any direct perceptual evidence; and (c) infants do not infer a hidden causal agent if the moving object was previously shown to be capable of self-generated motion.     

The influence of novelty and complexity on exploratory behavior in 12-month-old infants

This study investigated the influence of the novelty of the environment and the novelty and complexity of the objects (toys) it contained on the exploratory behavior of 12-month-old infants. Each infant was given a choice between novel and familiar toys located in two adjacent rooms (toy rooms). The novelty of the objects was manipulated by allowing the infants to play with one set of toys during a 5-min familiarization trial prior to the choice trial. The novetly of the environment was manipulated by allowing some infants to see, enter, and remain in the toy rooms during the familiarization trial. Finally, the complexity of the objects was manipulated by varying the number of familiar and novel toys; some Ss had four toys in each set (complex array) and some had only one (simple array). The results indicate that all three factors influenced the infants' exploratory behavior. Ss first approached, and spent more time manipulating, the novel than the familiar toys; they spent more time in the toy rooms if they were novel; and they spent more time manipulating the complex array of toys than the simple array.