Variability and patterns in children's media use and links with language development

AIM

Media use is widespread and rising, but how often and for what purpose young children use media varies, which has differential impacts on development. Yet little work has measured how and why children under 36 months use digital media or media's consequences for language.

METHODS

The current study measures how and why 17- to 30-month-old children use digital media and associations with their language abilities. The amount of use, type of activity and caregiver reasons for children's media use were then compared to the child's vocabulary and mean length of utterance.

RESULTS

About 17- to 30-month-old children are primarily exposed to TV/videos over other media forms, which are often used to occupy children. Video time (but not other activities) negatively predicts children's language. The negative impact of videos on vocabulary persists regardless of the reason for use, however, the effect of videos on expressive language may be tempered when videos are used for education or connecting.

CONCLUSION

Children under 36 months are using digital media at high rates. What they are doing and why they use media is critical to predict the effect it might have on language development. Further research and anticipatory guidance on the consequences of videos are needed.

Comparing apples to manzanas and oranges to naranjas: A new measure of English-Spanish vocabulary for dual language learners

The valid assessment of vocabulary development in dual-language-learning infants is critical to developmental science. We developed the Dual Language Learners English-Spanish (DLL-ES) Inventories to measure vocabularies of U.S. English-Spanish DLLs. The inventories provide translation equivalents for all Spanish and English items on Communicative Development Inventory (CDI) short forms; extended inventories based on CDI long forms; and Spanish language-variety options. Item-Response Theory analyses applied to Wordbank and Web-CDI data (n = 2603, 12-18 months; n = 6722, 16-36 months; half female; 1% Asian, 3% Black, 2% Hispanic, 30% White, 64% unknown) showed near-perfect associations between DLL-ES and CDI long-form scores. Interviews with 10 Hispanic mothers of 18- to 24-month-olds (2 White, 1 Black, 7 multi-racial; 6 female) provide a proof of concept for the value of the DLL-ES for assessing the vocabularies of DLLs.

Iconicity ratings for 14,000+ English words

Iconic words and signs are characterized by a perceived resemblance between aspects of their form and aspects of their meaning. For example, in English, iconic words include peep and crash, which mimic the sounds they denote, and wiggle and zigzag, which mimic motion. As a semiotic property of words and signs, iconicity has been demonstrated to play a role in word learning, language processing, and language evolution. This paper presents the results of a large-scale norming study for more than 14,000 English words conducted with over 1400 American English speakers. We demonstrate the utility of these ratings by replicating a number of existing findings showing that iconicity ratings are related to age of acquisition, sensory modality, semantic neighborhood density, structural markedness, and playfulness. We discuss possible use cases and limitations of the rating dataset, which is made publicly available.

Pre-pandemic Executive Function Protects Against Pandemic Anxiety in Children with and Without Autism Spectrum Disorder

The COVID-19 pandemic may have exacerbated depression, anxiety, and executive function (EF) difficulties in children with autism spectrum disorder (ASD). EF skills have been positively associated with mental health outcomes. Here, we probed the psychosocial impacts of pandemic responses in children with and without ASD by relating pre-pandemic EF assessments with anxiety and depression symptoms several months into the pandemic. We found that pre-pandemic inhibition and shifting difficulties, measured by the Behavior Rating Inventory of Executive Function, predicted higher risk of anxiety symptoms. These findings are critical for promoting community recovery and maximizing clinical preparedness to support children at increased risk for adverse psychosocial outcomes.

Investigating Children's Interactions in Preschool Classrooms: An Overview of Research Using Automated Sensing Technologies

New technologies that combine digital sensors with automated processing algorithms are now being deployed to study preschool classrooms. This article provides an overview of these new sensing technologies, focusing on automated speaker classification, the analysis of children's and teachers' speech, and the detection and analysis of their movements over the course of the school day. Findings from recent studies utilizing these technologies are presented to illustrate the contribution of these sensing technologies to our understanding of classroom processes that predict children's language and social development. In particular, the potential to collect extended real-time data on the speech and movement of all children and teachers in a classroom provides a broader window on the variability of individual children's interactions with peers and teachers and their integration into classroom social networks. The article describes current challenges related to the use of sensing technologies in preschool settings, as well as advances that may overcome these challenges and allow for more in-depth investigations of children's early classroom experiences.

Automated measures of vocal interactions and engagement in inclusive preschool classrooms

Classroom engagement plays a crucial role in preschoolers' development, yet the correlates of engagement, especially among children with autism spectrum disorder (ASD) and developmental delays (DD), remains unknown. This study examines levels of engagement with classroom social partners and tasks among children in three groups ASD, DD, and typical development (TD). Here, we asked whether children's vocal interactions (vocalizations to and from peers and teachers) were associated with their classroom engagement with social partners (peers and teachers) and with tasks, and whether the association between classroom engagement and vocal interactions differed between children in the ASD group and their peers in the DD and TD groups. Automated measures of vocalizations and location quantified children's vocal interactions with peers and teachers over the course of the school year. Automated location and vocalization data were used to capture both (1) children's vocal output to specific peers and teachers, and (2) the vocal input they received from those peers and teachers. Participants were 72 3-5-year-olds (Mage  = 48.6 months, SD = 7.0, 43% girls) and their teachers. Children in the ASD group displayed lower engagement with peers, teachers, and tasks than children in the TD group; they also showed lower engagement with peers than children in the DD group. Overall, children's own vocalizations were positively associated with engagement with social partners. Thus, although children in the ASD group tend to have lower engagement scores than children in the TD group, active participation in vocal interactions appears to support their classroom engagement with teachers and peers.

Comparing Scores on the Peabody Picture Vocabulary Test and Receptive One-Word Picture Vocabulary Test in Preschoolers With and Without Hearing Loss

PURPOSE

We sought to compare raw scores, standard scores, and age equivalences on two commonly used vocabulary tests, the Peabody Picture Vocabulary Test (PPVT) and the Receptive One-Word Picture Vocabulary Test (ROWPVT).

METHOD

Sixty-two children, 31 with hearing loss (HL) and 31 with normal hearing (NH), were given both the PPVT and ROWPVT as part of an ongoing longitudinal study of emergent literacy development in preschoolers with and without HL. All children were between 3 and 4 years old at administration, and the two tests were administered within 3 weeks of each other. Both tests were given again 6 months later. Standard scores and age equivalencies were calculated for both tests using published guidelines.

RESULTS

There was no significant effect of test for any of our analyses. However, there was a main effect of time, with both standard scores and age equivalencies being significantly higher at the second test. Children with NH had significantly higher standard scores and age equivalencies than children with NH, but there was no interaction between hearing status and time, suggesting that the two groups were growing at the same rate.

CONCLUSIONS

Clinicians can be comfortable administering both the PPVT and ROWPVT to estimate children's vocabulary levels, but there may be practice effects when administering the tests twice within a calendar year. These data also indicate that children with HL continue to lag behind their peers with NH on vocabulary development.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.23232848.

Understanding speech and language in tuberous sclerosis complex

Tuberous Sclerosis Complex (TSC), is a neurocutaneous disorder, associated with a high prevalence of autism spectrum disorder (ASD; ∼50% of individuals). As TSC is a leading cause of syndromic ASD, understanding language development in this population would not only be important for individuals with TSC but may also have implications for those with other causes of syndromic and idiopathic ASD. In this mini review, we consider what is known about language development in this population and how speech and language in TSC are related to ASD. Although up to 70% of individuals with TSC report language difficulties, much of the limited research to date on language in TSC has been based on summary scores from standardized assessments. Missing is a detailed understanding of the mechanisms driving speech and language in TSC and how they relate to ASD. Here, we review recent work suggesting that canonical babbling and volubility-two precursors of language development that predict the emergence of speech and are delayed in infants with idiopathic ASD-are also delayed in infants with TSC. We then look to the broader literature on language development to identify other early precursors of language development that tend to be delayed in children with autism as a guide for future research on speech and language in TSC. We argue that vocal turn-taking, shared attention, and fast mapping are three such skills that can provide important information about how speech and language develop in TSC and where potential delays come from. The overall goal of this line of research is to not only illuminate the trajectory of language in TSC with and without ASD, but to ultimately find strategies for earlier recognition and treatment of the pervasive language difficulties in this population.

Objective Measurement of Social Gaze and Smile Behaviors in Children with Suspected Autism Spectrum Disorder During Administration of the Autism Diagnostic Observation Schedule, 2nd Edition

Best practice for the assessment of autism spectrum disorder (ASD) symptom severity relies on clinician ratings of the Autism Diagnostic Observation Schedule, 2nd Edition (ADOS-2), but the association of these ratings with objective measures of children's social gaze and smiling is unknown. Sixty-six preschool-age children (49 boys, M = 39.97 months, SD = 10.58) with suspected ASD (61 confirmed ASD) were administered the ADOS-2 and provided social affect calibrated severity scores (SA CSS). Children's social gaze and smiling during the ADOS-2, captured with a camera contained in eyeglasses worn by the examiner and parent, were obtained via a computer vision processing pipeline. Children who gazed more at their parents (p = .04) and whose gaze at their parents involved more smiling (p = .02) received lower social affect severity scores, indicating fewer social affect symptoms, adjusted R² = .15, p = .003.

Objective quantification of homophily in children with and without disabilities in naturalistic contexts

Homophily, the tendency for individuals to preferentially interact with others similar to themselves is typically documented via self-report and, for children, adult report. Few studies have investigated homophily directly using objective measures of social movement. We quantified homophily in children with developmental disabilities (DD) and typical development (TD) using objective measures of position/orientation in preschool inclusion classrooms, designed to promote interaction between these groups of children. Objective measurements were collected using ultra-wideband radio-frequency tracking to determine social approach and social contact, measures of social movement and interaction. Observations of 77 preschoolers (47 with DD, and 30 TD) were conducted in eight inclusion classrooms on a total of 26 days. We compared DD and TD groups with respect to how children approached and shared time in social contact with peers using mixed-effects models. Children in concordant dyads (DD-DD and TD-TD) both moved toward each other at higher velocities and spent greater time in social contact than discordant dyads (DD-TD), evidencing homophily. DD-DD dyads spent less time in social contact than TD-TD dyads but were comparable to TD-TD dyads in their social approach velocities. Children's preference for similar peers appears to be a pervasive feature of their naturalistic interactions.

Classroom language during COVID-19: Associations between mask-wearing and objectively measured teacher and preschooler vocalizations

During the COVID-19 pandemic, mask-wearing in classrooms has become commonplace. However, there are little data on the effect of face-masks on children’s language input and production in educational contexts, like preschool classrooms which over half of United States children attend. Leveraging repeated objective measurements, we longitudinally examined child and teacher speech-related vocalizations in two cohorts of 3.5–4.5-year-old children enrolled in the same oral language classroom that included children with and without hearing loss. Cohort 1 was observed before COVID-19 (no face-masks, N = 20) and Cohort 2 was observed during COVID-19 (with face-masks; N = 15). Vocalization data were collected using child-worn audio recorders over 12 observations spanning two successive school years, yielding 9.09 mean hours of audio recording per child. During COVID-19 teachers produced a higher number of words per minute than teachers observed prior to COVID-19. However, teacher vocalizations during COVID-19 contained fewer unique phonemes than teacher vocalizations prior to COVID-19. Children observed during COVID-19 did not exhibit deficits in the duration, rate, or phonemic diversity of their vocalizations compared to children observed prior to COVID-19. Children observed during COVID-19 produced vocalizations that were longer in duration than vocalizations of children observed prior to COVID-19. During COVID-19 (but not before), children who were exposed to a higher number of words per minute from teachers produced more speech-related vocalizations per minute themselves. Overall, children with hearing loss were exposed to teacher vocalizations that were longer in duration, more teacher words per minute, and more phonemically diverse teacher speech than children with typical hearing. In terms of production, children with hearing loss produced vocalizations that were longer in duration than the vocalizations of children with typical hearing. Among children observed during COVID-19, children with hearing loss exhibited a higher vocalization rate than children with typical hearing. These results suggest that children’s language production is largely unaffected by mask use in the classroom and that children can benefit from the language they are exposed to despite teacher mask-wearing.

Coordination of Caregiver Naming and Children’s Exploration of Solid Objects and Nonsolid Substances

When a caregiver names objects dominating a child’s view, the association between object and name is unambiguous and children are more likely to learn the object’s name. Children also learn to name things other than solid objects, including nonsolid substances like applesauce. However, it is unknown how caregivers structure linguistic and exploratory experiences with nonsolids to support learning. In this exploratory study of caregivers and children (n = 14, 8 girls; M = 20.50 months) we compare caregiver-child free-play with novel solid objects and novel nonsolid substances to identify the linguistic and exploratory experiences associated with children’s word learning. We found systematic differences in interactions with novel objects, such that children performed more manual actions on solids than nonsolids and caregivers named solids more than nonsolids. Additionally, there was less synchrony between caregivers’ naming and children’s manual and visual exploration of nonsolids than solids. Consistent with prior work, we found that synchronous naming was associated with accurate recognition of solid object names. However, naming synchrony was not associated with recognition of nonsolid substance names or with generalization. Together these findings, though exploratory, suggest the coordination of caregiver-child play can shape what children remember about novel word-object associations for solid objects, but not nonsolid substances.

Objective measurement of vocalizations in the assessment of autism spectrum disorder symptoms in preschool age children

Assessment of autism spectrum disorder (ASD) relies on expert clinician observation and judgment, but objective measurement tools have the potential to provide additional information on ASD symptom severity. Diagnostic evaluations for ASD typically include the autism diagnostic observation schedule (ADOS-2), a semi-structured assessment composed of a series of social presses. The current study examined associations between concurrent objective features of child vocalizations during the ADOS-2 and examiner-rated autism symptom severity. The sample included 66 children (49 male; M = 40 months, SD = 10.58) evaluated in a university-based clinic, 61 of whom received an ASD diagnosis. Research reliable administration of the ADOS-2 provided social affect (SA) and restricted and repetitive behavior (RRB) calibrated severity scores (CSS). Audio was recorded from examiner-worn eyeglasses during the ADOS-2 and child and adult speech were differentiated with LENA SP Hub. PRAAT was used to ascertain acoustic features of the audio signal, specifically the mean fundamental vocal frequency (F0) of LENA-identified child speech-like vocalizations (those with phonemic content), child cry vocalizations, and adult speech. Sphinx-4 was employed to estimate child and adult phonological features indexed by the average consonant and vowel count per vocalization. More than a quarter of the variance in ADOS-2 RRB CSS was predicted by the combination of child phoneme count per vocalization and child vocalization F0. Findings indicate that both acoustic and phonological features of child vocalizations are associated with expert clinician ratings of autism symptom severity. LAY SUMMARY: Determination of the severity of autism spectrum disorder is based in part on expert (but subjective) clinician observations during the ADOS-2. Two characteristics of child vocalizations-a smaller number of speech-like sounds per vocalization and higher pitched vocalizations (including cries)-were associated with greater autism symptom severity. The results suggest that objectively ascertained characteristics of children's vocalizations capture variance in children's restricted and repetitive behaviors that are reflected in clinician severity indices.

Reciprocal Patterns of Peer Speech in Preschoolers with and without Hearing Loss

Children with hearing loss often attend inclusive preschool classrooms aimed at improving their spoken language skills. Although preschool classrooms are fertile environments for vocal interaction with peers, little is known about the dyadic processes that influence children's speech to one another and foster their language abilities and how these processes may vary in children with hearing loss. We used new objective measurement approaches to identify and quantify children's vocalizations during social contact, as determined by children's proximity and mutual orientation. The contributions of peer vocalizations to children's future vocalizations and language abilities were examined in oral language inclusion classrooms containing children with hearing loss who use hearing aids or cochlear implants and their typically hearing peers. Across over 600 hours of recorded vocal interactions of twenty-nine 2.5-3.5 year olds (16 girls) in three cohorts of children in a classroom, we found that vocalizations from each peer on a given observation predicted a child's vocalizations to that same peer on the subsequent observation. Children who produced more vocalizations to their peers had higher receptive and expressive language abilities, as measured by a standardized end-of-year language assessment. In fact, vocalizations from peers had an indirect association with end-of-year language abilities as mediated by children's vocalizations to peers. These findings did not vary as a function of hearing status. Overall, then, the results demonstrate the importance of dyadic peer vocal interactions for children's language use and abilities.

Objectively measured teacher and preschooler vocalizations: Phonemic diversity is associated with language abilities

Over half of US children are enrolled in preschools, where the quantity and quality of language input from teachers are likely to affect children's language development. Leveraging repeated objective measurements, we examined the rate per minute and phonemic diversity of child and teacher speech-related vocalizations in preschool classrooms and their association with children's end-of-year receptive and expressive language abilities measured with the Preschool Language Scales (PLS-5). Phonemic diversity was computed as the number of unique consonants and vowels in a speech-related vocalization. We observed three successive cohorts of 2.5-3.5-year-old children enrolled in an oral language classroom that included children with and without hearing loss (N = 29, 16 girls, 14 Hispanic). Vocalization data were collected using child-worn audio recorders over 34 observations spanning three successive school years, yielding 21.53 mean hours of audio recording per child. The rate of teacher vocalizations positively predicted the rate of children's speech-related vocalizations while the phonemic diversity of teacher vocalizations positively predicted the phonemic diversity of children's speech-related vocalizations. The phonemic diversity of children's speech-related vocalizations was a stronger predictor of end-of-year language abilities than the rate of children's speech-related vocalizations. Mediation analyses indicated that the phonemic diversity of teacher vocalizations was associated with children's receptive and expressive language abilities to the extent that it influenced the phonemic diversity of children's own speech-related vocalizations. The results suggest that qualitatively richer language input expands the phonemic diversity of children's speech, which in turn is associated with language abilities.

Computational approaches to understanding interaction and development

Audio-visual recording and location tracking produce enormous quantities of digital data with which researchers can document children's everyday interactions in naturalistic settings and assessment contexts. Machine learning and other computational approaches can produce replicable, automated measurements of these big behavioral data. The economies of scale afforded by repeated automated measurements offer a potent approach to investigating linkages between real-time behavior and developmental change. In our work, automated measurement of audio from child-worn recorders-which quantify the frequency of child and adult speech and index its phonemic complexity-are paired with ultrawide radio tracking of children's location and interpersonal orientation. Applications of objective measurement indicate the influence of adult behavior in both expert ratings of attachment behavior and ratings of autism severity, suggesting the role of dyadic factors in these "child" assessments. In the preschool classroom, location/orientation measures provide data-driven measures of children's social contact, fertile ground for vocal interactions. Both the velocity of children's movement toward one another and their social contact with one another evidence homophily: children with autism spectrum disorder, other developmental disabilities, and typically developing children were more likely to interact with children in the same group even in inclusive preschool classrooms designed to promote interchange between all children. In the vocal domain, the frequency of peer speech and the phonemic complexity of teacher speech predict the frequency and phonemic complexity of children's own speech over multiple timescales. Moreover, children's own speech predicts their assessed language abilities across disability groups, suggesting how everyday interactions facilitate development.

Vocabulary Development and the Shape Bias in Children With Hearing Loss

Purpose Although children with hearing loss (HL) can benefit from cochlear implants (CIs) and hearing aids (HAs), they often show language delays. Moreover, little is known about the mechanisms by which children with HL learn words. One mechanism by which typically hearing (TH) children learn words is by acquiring word learning biases such as the "shape bias," that is, generalizing the names of novel solid objects by similarity in shape. In TH children, the shape bias emerges out of regularities in the early vocabulary and, once acquired, has consequences for subsequent vocabulary development. Method Here, we ask whether children with HL exhibit similar word learning biases as TH children. In the current study, nineteen 2- to 3.5-year-old children with HL generalized the names of novel objects by similarity in shape or material. We compared their performance to that of 20 TH children matched on age and 20 TH children matched on vocabulary size. Results Children with HL were significantly less likely than age-matched TH children and vocabulary-matched TH children to generalize novel names to objects of the same shape. However, there was also an interaction such that vocabulary has a stronger effect on novel noun generalization for those with HL than for those who are TH. Exploratory analyses of children with HL reveal similar novel noun generalization and vocabulary sizes in children who use CIs and those who use HAs, regardless of hearing age or degree of HL. Conclusion Together, the results suggest that, although vocabulary knowledge drives development of the shape bias in general for all children, it may be especially important for children with HL, who are at risk for language delays.

A granular perspective on inclusion: Objectively measured interactions of preschoolers with and without autism

Children's preschool experiences have consequences for development. However, it is not clear how children's real-time interactions with peers affect their language development; nor is it clear whether these processes differ between children with autism spectrum disorder (ASD) and two other groups of children, those with general developmental delays (DD) and typically developing (TD) children. We used objective measures of movement and vocalizations to quantify children's real-time dyadic vocal interactions and quantify classroom social networks. Participants included 56 preschoolers (22 female; M = 50.14 months) in five inclusive classrooms for children with ASD or DD and their TD peers. Each class was observed monthly on two to five occasions. Overall, children vocalized more to peers who had vocalized more to them in the previous observation. These dyadic vocalization patterns were associated with group differences in social network analyses. Modularity, the cohesiveness of group ties, was lower among children with ASD than it was among TD children or children with DD. Individually, children with ASD exhibited lower total levels of vocalizations with peers (lower degree centrality) than TD children and children with DD. In an exploratory analysis with a subset of the participants, children's degree centrality was strongly associated with their end-of-year assessed language abilities, even when accounting for mean differences between groups. Findings highlight the impact peers and social networks play in real-time language use and in the developing language abilities of children with ASD in inclusion classrooms. LAY SUMMARY: This study objectively measured associations between children's peer vocal interactions and assessed language abilities in inclusion classrooms for children with autism spectrum disorder (ASD) and their peers. All children benefited from peers talking to them, but children with ASD were less central to classroom speech networks than were typically developing children. Children's centrality to social speech networks, regardless of ASD status, was associated with assessed language abilities.

What Is the Buzz About Iconicity? How Iconicity in Caregiver Speech Supports Children's Word Learning

One cue that may facilitate children's word learning is iconicity, or the correspondence between a word's form and meaning. Some have even proposed that iconicity in the early lexicon may serve to help children learn how to learn words, supporting the acquisition of even noniconic, or arbitrary, word-referent associations. However, this proposal remains untested. Here, we investigate the iconicity of caregivers' speech to young children during a naturalistic free-play session with novel stimuli and ask whether the iconicity of caregivers' speech facilitates children's learning of the noniconic novel names of those stimuli. Thirty-four 1.5-2-year-olds (19 girls; half monolingual English learners and half bilingual English-Spanish learners) participated in a naturalistic free-play task with their caregivers followed by a test of word-referent retention. We found that caregivers' use of iconicity, particularly in utterances in which they named the novel stimuli, was associated with the likelihood that children learned that novel name. This result held even when controlling for other factors associated with word learning, such as the concreteness and frequency of words in caregiver speech. Together, the results demonstrate that iconicity not only can serve to help children identify the referent of novel words (as in previous research) but can also support their ability to retain even noniconic word-referent mappings.

Shaping semantic networks with transcranial direct current stimulation

Images depict specific objects (e.g., a specific dog), yet are named with categorical labels (e.g., “dog”). We examined how semantic representations activated by images may be influenced by implicit labelling. Participants saw images of familiar objects and generated words associated with each image while undergoing transcranial direct current stimulation over the posterior superior temporal gyrus. Additional participants judged how representative generated associates were of the picture category and guessed the category based on the associates. Anodal stimulation was predicted to up-regulate labelling and thereby increase the extent to which participants produced associate that were more representative of the pictured category. Associates generated by anodally stimulated subjects were found to be more representative and enabled more accurate guessing of the category from which they were generated. The general pattern of results was replicated in a follow-up study using words rather than picture cues. Together these results suggest labelling may help stabilise semantic representations, leading to more robust representation of category-relevant information.

Rethinking Emergent Literacy in Children With Hearing Loss

Long-term literacy outcomes for children with hearing loss, particularly those with severe-to-profound deafness who are fitted with cochlear implants (CIs) lag behind those of children with normal hearing (NH). The causes for these long-term deficits are not fully clear, though differences in auditory access between children who use CIs and those with NH may be a partial cause. This paper briefly reviews the emergent literacy model as proposed by Whitehurst and Lonigan (1998). We then examine the development of each of Whitehurst and Lonigan’s identified factors in children who use CIs and how the extant knowledge of language and literacy development in children who use CIs may bear on the emergent literacy model. We then propose to modify the model for children who use CIs based on their unique developmental trajectories, influenced at least in part by their unique auditory access. We conclude with future directions for further development of an evidence-based emergent literacy model for children who use CIs and how this model could be used to inform intervention.

Validation of continuous measures of peer social interaction with self- and teacher-reports of friendship and social engagement

The present study validates a new procedure that combines continuous measures of proximity (Ubisense) and vocalization (LENA) into measures of peer social interaction. The data were collected from 4 boys and 5 girls (ages 2-3 at the outset) on 8 separate days (3-4 hours per day) over the course of an academic year. Teacher reports of friendship were positively correlated with continuous measures of dyadic social interaction (i.e., the amount of time two children spent in proximity to one another, talking). Self-reports of reciprocated friendship were marginally correlated with continuous measures of dyadic social interaction, but only in the spring semester (when children were older and their reports of friendship more reliable). At the individual level, peer nominations of likeability, and teacher ratings of sociability and withdrawal were correlated with continuous measures of social interaction (i.e., the amount of time a child spent in proximity to other children, talking).

The Heterogeneity of Word Learning Biases in Late-Talking Children

Purpose The particular statistical approach researchers choose is intimately connected to the way they conceptualize their questions, which, in turn, can influence the conclusions they draw. One particularly salient area in which statistics influence our conclusions is in the context of atypical development. Traditional statistical approaches such as t tests or analysis of variance lend themselves to a focus on group differences, downplaying the heterogeneity that exists within so many atypically developing populations. Understanding such variability is important-classification of what a disorder is, an individual's diagnosis, and whether or not a child receives intervention all directly relate to an accurate classification of the disorder and individual's abilities compared to their typically developing peers. Method Here, we use word learning biases (i.e., shape and material biases) in late-talking children as a sample case and employ a variety of statistical approaches to compare the conclusions those approaches might warrant. Results We argue that advanced statistical approaches, such as mixed-effects regression, can help us make sense of heterogeneity and are more consistent with a modern dimensional view of language disorders. Conclusions Accurate characterization of late-talking children (and others at risk for delays) and their prognoses is necessary for accurate diagnosis and implementation of appropriate target interventions. It therefore requires rigorous statistical analyses that can capture and allow for interpretation of the heterogeneity inherent in populations with language delays and disorders.

Reproducibility and a unifying explanation: Lessons from the shape bias

The goal of science is to advance our understanding of particular phenomena. However, in the field of development, the phenomena of interest are complex, multifaceted, and change over time. Here, we use three decades of research on the shape bias to argue that while replication is clearly an important part of the scientific process, integration across the findings of many studies that include variations in procedure is also critical to create a coherent understanding of the thoughts and behaviors of young children. The "shape bias," or the tendency to generalize a novel label to novel objects of the same shape, is a reliable and robust behavioral finding and has been shown to predict future vocabulary growth and possible language disorders. Despite the robustness of the phenomenon, the way in which the shape bias is defined and tested has varied across studies and laboratories. The current review argues that differences in performance that come from even seemingly minor changes to the participants or task can offer critical insight to underlying mechanisms, and that working to incorporate data from multiple labs is an important way to reveal how task variation and a child's individual pathway creates behavior-a key issue for understanding developmental phenomena.

Continuous measurement of dynamic classroom social interactions

Human observations can only capture a portion of ongoing classroom social activity, and are not ideal for understanding how children’s interactions are spatially structured. Here we demonstrate how social interaction can be investigated by modeling automated continuous measurements of children’s location and movement using a commercial system based on radio frequency identification. Continuous location data were obtained from 16 five-year-olds observed during three 1-h classroom free play observations. Illustrative coordinate mapping indicated that boys and girls tended to cluster in different physical locations in the classroom, but there was no suggestion of gender differences in children’s velocity (i.e., speed of movement). To detect social interaction, we present the radial distribution function, an index of when children were in social contact at greater than chance levels. Rank-order plots indicated that children were in social contact tens to hundreds of times more with some peers than others. We illustrate the use of social ties (higher than average levels of social contact) to visualize the classroom network. Analysis of the network suggests that transitivity is a potential lens through which to examine male, female, and mixed-sex cliques. The illustrative findings suggest the validity of the new measurement approach by re-examining well-established gender segregation findings from a new perspective.

A year in words: The dynamics and consequences of language experiences in an intervention classroom

Children from low SES backgrounds hear, on average, fewer words at home than those from high SES backgrounds. This word gap is associated with widening achievement differences in children’s language abilities and school readiness. However relatively little is known about adult and child speech in childcare settings, in which approximately 30% of American children are enrolled. We examined the influence of teacher and peer language input on children’s in-class language use and language development in an intervention classroom for low-SES, high-risk 2- to 3-year-olds. Over the course of a year, day-long recordings of the classroom were collected weekly with LENA recorders. Using LENA software algorithms, we found that language input from peers was positively related to children’s in-class language use, both in-the-moment and over the course of each day, as were the number of conversational turns in which children and teachers engaged Both peer input and conversational turns with teachers were also positively related to children’s language development rates, as indexed by increases in vocabulary size. Together these results indicate the importance of child-specific rates of classroom language input in the language development of high-risk, preschoolers.

Iconicity in the speech of children and adults

Iconicity - the correspondence between form and meaning - may help young children learn to use new words. Early-learned words are higher in iconicity than later learned words. However, it remains unclear what role iconicity may play in actual language use. Here, we ask whether iconicity relates not just to the age at which words are acquired, but also to how frequently children and adults use the words in their speech. If iconicity serves to bootstrap word learning, then we would expect that children should say highly iconic words more frequently than less iconic words, especially early in development. We would also expect adults to use iconic words more often when speaking to children than to other adults. We examined the relationship between frequency and iconicity for approximately 2000 English words. Replicating previous findings, we found that more iconic words are learned earlier. Moreover, we found that more iconic words tend to be used more by younger children, and adults use more iconic words when speaking to children than to other adults. Together, our results show that young children not only learn words rated high in iconicity earlier than words low in iconicity, but they also produce these words more frequently in conversation - a pattern that is reciprocated by adults when speaking with children. Thus, the earliest conversations of children are relatively higher in iconicity, suggesting that this iconicity scaffolds the production and comprehension of spoken language during early development.

Is a Pink Cow Still a Cow? Individual Differences in Toddlers' Vocabulary Knowledge and Lexical Representations

When a toddler knows a word, what does she actually know? Many categories have multiple relevant properties; for example, shape and color are relevant to membership in the category banana. How do toddlers prioritize these properties when recognizing familiar words, and are there systematic differences among children? In this study, toddlers viewed pairs of objects associated with prototypical colors. On some trials, objects were typically colored (e.g., Holstein cow and pink pig); on other trials, colors were switched (e.g., pink cow and Holstein-patterned pig). On each trial, toddlers were directed to find a target object. Overall, recognition was disrupted when colors were switched, as measured by eye movements. Moreover, individual differences in vocabularies predicted recognition differences: Toddlers who say fewer shape-based words were more disrupted by color switches. "Knowing" a word may not mean the same thing for all toddlers; different toddlers prioritize different facets of familiar objects in their lexical representations.

Near or far: The effect of spatial distance and vocabulary knowledge on word learning

The current study investigated the role of spatial distance in word learning. Two-year-old children saw three novel objects named while the objects were either in close proximity to each other or spatially separated. Children were then tested on their retention for the name-object associations. Keeping the objects spatially separated from each other during naming was associated with increased retention for children with larger vocabularies. Children with a lower vocabulary size demonstrated better retention if they saw objects in close proximity to each other during naming. This demonstrates that keeping a clear view of objects during naming improves word learning for children who have already learned many words, but keeping objects within close proximal range is better for children at earlier stages of vocabulary acquisition. The effect of distance is therefore not equal across varying vocabulary sizes. The influences of visual crowding, cognitive load, and vocabulary size on word learning are discussed.

Iconicity in English and Spanish and Its Relation to Lexical Category and Age of Acquisition

Signed languages exhibit iconicity (resemblance between form and meaning) across their vocabulary, and many non-Indo-European spoken languages feature sizable classes of iconic words known as ideophones. In comparison, Indo-European languages like English and Spanish are believed to be arbitrary outside of a small number of onomatopoeic words. In three experiments with English and two with Spanish, we asked native speakers to rate the iconicity of ~600 words from the English and Spanish MacArthur-Bates Communicative Developmental Inventories. We found that iconicity in the words of both languages varied in a theoretically meaningful way with lexical category. In both languages, adjectives were rated as more iconic than nouns and function words, and corresponding to typological differences between English and Spanish in verb semantics, English verbs were rated as relatively iconic compared to Spanish verbs. We also found that both languages exhibited a negative relationship between iconicity ratings and age of acquisition. Words learned earlier tended to be more iconic, suggesting that iconicity in early vocabulary may aid word learning. Altogether these findings show that iconicity is a graded quality that pervades vocabularies of even the most “arbitrary” spoken languages. The findings provide compelling evidence that iconicity is an important property of all languages, signed and spoken, including Indo-European languages.

The role of language in multi-dimensional categorization: evidence from transcranial direct current stimulation and exposure to verbal labels

Human concepts differ in their dimensionality. Some, like green-things, require representing one dimension while abstracting over many others. Others, like bird, have higher dimensionality due to numerous category-relevant properties (feathers, two-legs). Converging evidence points to the importance of verbal labels for forming low-dimensional categories. We examined the role of verbal labels in categorization by (1) using transcranial direct current stimulation over Wernicke's area (2) providing explicit verbal labels during a category learning task. We trained participants on a novel perceptual categorization task in which categories could be distinguished by either a uni- or bi-dimensional criterion. Cathodal stimulation over Wernicke's area reduced reliance on single-dimensional solutions, while presenting informationally redundant novel labels reduced reliance on the dimension that is normally incidental in the real world. These results provide further evidence that implicit and explicit verbal labels support the process of human categorization.

Highchair philosophers: the impact of seating context-dependent exploration on children's naming biases

We examine developmental interactions between context, exploration, and word learning. Infants show an understanding of how nonsolid substances are categorized that does not reliably transfer to learning how these categories are named in laboratory tasks. We argue that what infants learn about naming nonsolid substances is contextually bound - most nonsolids that toddlers are familiar with are foods and thus, typically experienced when sitting in a highchair. We asked whether 16-month-old children's naming of nonsolids would improve if they were tested in that typical context. Children tested in the highchair demonstrated better understanding of how nonsolids are named. Furthermore, context-based differences in exploration drove differences in the properties attended to in real-time. We discuss what implications this context-dependency has for understanding the development of an ontological distinction between solids and nonsolids. Together, these results demonstrate a developmental cascade between context, exploration, and word learning.

Grounding word learning in space

Humans and objects, and thus social interactions about objects, exist within space. Words direct listeners' attention to specific regions of space. Thus, a strong correspondence exists between where one looks, one's bodily orientation, and what one sees. This leads to further correspondence with what one remembers. Here, we present data suggesting that children use associations between space and objects and space and words to link words and objects—space binds labels to their referents. We tested this claim in four experiments, showing that the spatial consistency of where objects are presented affects children's word learning. Next, we demonstrate that a process model that grounds word learning in the known neural dynamics of spatial attention, spatial memory, and associative learning can capture the suite of results reported here. This model also predicts that space is special, a prediction supported in a fifth experiment that shows children do not use color as a cue to bind words and objects. In a final experiment, we ask whether spatial consistency affects word learning in naturalistic word learning contexts. Children of parents who spontaneously keep objects in a consistent spatial location during naming interactions learn words more effectively. Together, the model and data show that space is a powerful tool that can effectively ground word learning in social contexts.

The shape of the vocabulary predicts the shape of the bias

Children acquire attentional biases that help them generalize novel words to novel objects. Researchers have proposed that these biases arise from regularities in the early noun vocabulary children learn and suggest that the specifics of the biases should be tied to the specifics of individual children’s vocabularies. However, evidence supporting this proposal to date comes from studies of group means. The current study examines the relations between the statistics of the nouns young children learn and the similarities and differences in the biases they demonstrate. We show that individual differences in vocabulary structure predict individual differences in novel noun generalization. Thus, these data support the proposal that word learning biases emerge from the regularities present in individual children’s vocabularies and, importantly, that children’s on-line attention during an experiment is mediated by instances of past learning.

Learn locally, think globally. Exemplar variability supports higher-order generalization and word learning

Research suggests that variability of exemplars supports successful object categorization; however, the scope of variability's support at the level of higher-order generalization remains unexplored. Using a longitudinal study, we examined the role of exemplar variability in first- and second-order generalization in the context of nominal-category learning at an early age. Sixteen 18-month-old children were taught 12 categories. Half of the children were taught with sets of highly similar exemplars; the other half were taught with sets of dissimilar, variable exemplars. Participants' learning and generalization of trained labels and their development of more general word-learning biases were tested. All children were found to have learned labels for trained exemplars, but children trained with variable exemplars generalized to novel exemplars of these categories, developed a discriminating word-learning bias generalizing labels of novel solid objects by shape and labels of nonsolid objects by material, and accelerated in vocabulary acquisition. These findings demonstrate that object variability leads to better abstraction of individual and global category organization, which increases learning outside the laboratory.

Aligning body and world: stable reference frames improve young children's search for hidden objects

This study investigated how young children's increasingly flexible use of spatial reference frames enables accurate search for hidden objects by using a task that 3-year-olds have been shown to perform with great accuracy and 2-year-olds have been shown to perform inaccurately. Children watched as an object was rolled down a ramp, behind a panel of doors, and stopped at a barrier visible above the doors. In two experiments, we gave 2- and 2.5-year-olds a strong reference frame by increasing the relative salience and stability of the barrier. In Experiment 1, 2.5-year-olds performed at above-chance levels with the more salient barrier. In Experiment 2, we highlighted the stability of the barrier (or ramp) by maximizing the spatial extent of each reference frame across the first four training trials. Children who were given a stable barrier (and moving ramp) during these initial trials performed at above-chance levels and significantly better than children who were given a stable ramp (and moving barrier). This work highlights that factors central to spatial cognition and motor planning-aligning egocentric and object-centered reference frames-play a role in the ramp task during this transitional phase in development.

Representational momentum and children's sensori-motor representations of objects

Recent research has shown that 2-year-olds fail at a task that ostensibly only requires the ability to understand that solid objects cannot pass through other solid objects. Two experiments were conducted in which 2- and 3-year-olds judged the stopping point of an object as it moved at varying speeds along a path and behind an occluder, stopping at a barrier visible above the occluder. Three-year-olds were able to take into account the barrier when searching for the object, while 2-year-olds were not. However, both groups judged faster moving objects to travel farther as indicated by their incorrect reaches. Thus, the results show that young children's sensori-motor representations exhibit a form of representational momentum. This unifies the perceptually based representations of early childhood with adults' dynamic representations that incorporate physical regularities but that are also available to conscious reasoning.

Expression of human glucocerebrosidase in long-term reconstituted mice following retroviral-mediated gene transfer into hematopoietic stem cells

A retroviral vector (GTN) in which the glucocerebrosidase (GCase) cDNA is driven by the Moloney murine leukemia virus (Mo-MuLV) long terminal repeat (LTR) was tested for transfer efficiency and expression of the GCase gene in long-term reconstituted mice. Eleven W/Wv mice were transplanted with unselected GTN-infected bone marrow cells and 10 of these mice were analyzed 3 months later. Seven of these 10 mice (70%) contained the intact proviral genome in bone marrow, spleen, and thymus. Of these 7,3 mice contained a high-copy number of the provirus in all the hematopoietic tissues tested. The mice contained anywhere from one to four proviral integration sites that were the same in all three tissues, indicating that these mice have been repopulated by one or more transduced multipotential hematopoietic stem cells. Five months after transplantation, bone marrow from the eleventh mouse was transplanted into secondary recipient animals. The secondary recipients contained the intact proviral genome in the bone marrow, spleen, thymus, and macrophages 4 months after the secondary transplantation. This further supports the conclusion that hematopoietic stem cells have indeed been targeted. Human GCase RNA was detected in all 7 mice containing the proviral DNA. These results demonstrate expression of the human GCase gene in the progeny of repopulating hematopoietic stem cells of mice following gene transfer.

Correction of glucocerebrosidase deficiency after retroviral-mediated gene transfer into hematopoietic progenitor cells from patients with Gaucher disease

Retroviral gene transfer has been used successfully to correct the glucocerebrosidase (GCase) deficiency in primary hematopoietic cells from patients with Gaucher disease. For this model of somatic gene therapy, we developed a high-titer, amphotropic retroviral vector designated NTG in which the human GCase gene was driven by the mutant polyoma virus enhancer/herpesvirus thymidine kinase gene (tk) promoter (Py+/Htk). NTG normalized GCase activity in transduced Gaucher fibroblasts and efficiently infected human monocytic and erythroleukemic cell lines. RNA blot-hybridization (Northern blot) analysis of these hematopoietic cell lines showed unexpectedly high-level expression from the Moloney murine leukemia virus long terminal repeat (Mo-MLV LTR) and levels of Py+/Htk enhancer/promoter-initiated human GCase RNA that approximated endogenous GCase RNA levels. Furthermore, NTG efficiently infected human hematopoietic progenitor cells. Detection (by means of the polymerase chain reaction) of the provirus in approximately one-third of NTG-infected progenitor colonies that had not been selected in G418-containing medium indicates that relative resistance to G418 underestimated the actual gene transfer efficiency. Northern blot analysis of NTG-infected, progenitor-derived cells showed expression from both the Mo-MLV LTR and the Py+/Htk enhancer/promoter. NTG-transduced hematopoietic progenitor cells from patients with Gaucher disease generated progeny in which GCase activity had been normalized.

Production of human glucocerebrosidase in mice after retroviral gene transfer into multipotential hematopoietic progenitor cells

The human glucocerebrosidase (GC) gene has been transferred efficiently into spleen colony-forming unit (CFU-S) multipotential hematopoietic progenitor cells, and production of human GC RNA and protein has been achieved in transduced CFU-S colonies. High-titer retroviral vectors containing the human GC cDNA were constructed. Mouse bone marrow cells were stimulated with hematopoietic growth factors, infected by coculture with producer cells, and injected into lethally irradiated animals. Four vectors were compared with respect to gene-transfer efficiency into CFU-S progenitors. One vector (G vector) required high concentrations of interleukins 3 and 6 during stimulation and coculture for efficient transduction of CFU-S progenitors. The remaining three vectors (NTG, GTN, and GI vectors) transduced these progenitors at infection frequencies approaching 100% using low concentrations of hematopoietic growth factors to stimulate cell division prior to and during the infection. Vectors using the viral long terminal repeat enhancer/promoter to drive the human GC cDNA produced high levels of human GC RNA in the progeny of CFU-S progenitors after gene transfer. When an internal herpes simplex thymidine kinase promoter assisted by a mutant polyoma enhancer was used to drive the human GC cDNA (NTG vector), little or no human GC RNA was detected in transduced CFU-S colonies. All three vectors producing human GC RNA in CFU-S colonies can generate human GC as detected by immunochemical analysis of CFU-S colonies. NTG vector-infected bone marrow cells were transplanted into W/Wv recipients to generate long-term reconstituted mice. The capacity of the viral long terminal repeat and the internal thymidine kinase promoter to direct synthesis of RNA in transduced bone marrow and spleen cells 5 months after bone marrow transplantation reflected the performance of these promoters in NTG-transduced CFU-S colonies.

Intravenous tubing containing burettes can be safely changed at 72 hour intervals

No studies testing the safety of changing intravenous systems containing in-line burettes at 72 hours in an intensive care setting have been performed. Patients entering a medical or surgical intensive care unit were alternatively assigned to have any line with an in-line burette changed at either 48 hour (105 patients) or 72 hour (65 patients) intervals. Daily quantitative cultures with a 2 ml aliquot of burette fluid were obtained. Contaminated burette fluid was detected in 60 of 1181 (5.0%, 95% confidence interval, 3.7% to 6.3%) samples from the burettes changed at 48 hour intervals, and in 40 of 901 (4.4%, 95% confidence interval, 3.0% to 5.8%) samples from 72 hour interval burettes. Significant bacterial contamination of burette fluid, defined as ten or more colonies per milliliter, occurred in only seven (0.6%) cultures from patients in the 48 hour interval group compared with only three (0.3%) cultures in the 72 hour group. None of the contaminated burette fluids was associated with a primary bacteremia. Change of in-line burettes in patients in intensive care at 72-hour intervals is safe and should result in substantial cost savings to hospitals.

Clinical evaluation of the Lumac bioluminescence method for screening urine specimens

A bioluminescence method for screening urine cultures to provide rapid reporting of negative specimens and to select appropriate urine cultures for direct application of automated identification methods was evaluated. A total of 2,000 specimens were processed in the Lumac Biocounter (3M, St. Paul, Minn.), and the results were compared with quantitative culture techniques by using a 0.001-ml inoculating loop. A total of 841 specimens were positive by the bioluminescence method; 291 specimens were culture positive (greater than or equal to 50,000 CFU of one or two organisms per ml). Positive cultures represented more than 20 different organisms. Approximately two-thirds of the false-positive results represented mixed flora or pure cultures of less than 5 X 10(4) organisms per ml. The predictive value of a negative result was 98.4%, reflecting a false-negative rate of only 0.7%. No advantages in cost or technician time were noted, but the Lumac method appears to be a useful technique in decreasing reporting time, especially for negative urine cultures.

Predictive value of surveillance skin cultures in total-parenteral-nutrition-related infection

To assess the importance of skin flora in the pathogenesis of infection complicating total parenteral nutrition and the predictive value of positive skin cultures for the development of infection 54 patients, who received 59 courses of total parenteral nutrition, were followed up. Three times per week, at the time of dressing and line changes, the skin at the site of insertion of the cannula was swabbed for culture. Results of skin cultures were compared with results of semiquantitative culture of the proximal intravascular portion of the cannula. Infected patients were defined as those having cannula cultures with greater than or equal to 15 colonies or those with primary septicaemia. 21 of 59 courses (36%) were associated with positive skin cultures; 14 of these 21 courses were associated with cannula infection, 2 with bacteraemia or fungaemia, and 12 with local infection. 38 of 59 (64%) courses had sterile skin cultures; in none of these 38 patients did infection develop (p less than 0.001). Skin colonisation was associated with otherwise unexplained fever (11 of 21 with positive skin culture versus 5 of 38 with negative skin culture, p less than 0.001), inflammation at the insertion site (13 of 21 versus 10 of 38, p less than 0.05), and violations of line protocol (11 of 21 versus 10 of 38, p less than 0.05). The absence of any organism on the skin had a negative predictive value of 98%, whereas the presence of an organism on the skin had a positive predictive value of 61%. Skin culture thus seems able to identify which patients receiving parenteral nutrition are at high risk of infection.