I: INTRODUCTION.

The majority of the world's children grow up learning two or more languages. The study of early bilingualism is central to current psycholinguistics, offering insights into issues such as transfer and interference in development. From an applied perspective, it poses a universal challenge to language assessment practices throughout childhood, as typically developing bilingual children usually underperform relative to monolingual norms when assessed in one language only. We measured vocabulary with Communicative Development Inventories for 372 24-month-old toddlers learning British English and one Additional Language out of a diverse set of 13 (Bengali, Cantonese, Dutch, French, German, Greek, Hindi-Urdu, Italian, Mandarin, Polish, Portuguese, Spanish, and Welsh). We furthered theoretical understanding of bilingual development by showing, for the first time, that linguistic distance between the child's two languages predicts vocabulary outcome, with phonological overlap related to expressive vocabulary, and word order typology and morphological complexity related to receptive vocabulary, in the Additional Language. Our study also has crucial clinical implications: we have developed the first bilingual norms for expressive and receptive vocabulary for 24-month-olds learning British English and an Additional Language. These norms were derived from factors identified as uniquely predicting CDI vocabulary measures: the relative amount of English versus the Additional Language in child-directed input and parental overheard speech, and infant gender. The resulting UKBTAT tool was able to accurately predict the English vocabulary of an additional group of 58 bilinguals learning an Additional Language outside our target range. This offers a pragmatic method for the assessment of children in the majority language when no tool exists in the Additional Language. Our findings also suggest that the effect of linguistic distance might extend beyond bilinguals' acquisition of early vocabulary to encompass broader cognitive processes, and could constitute a key factor in the study of the debated bilingual advantage.

Reduced parietal and visual cortical activation during global processing in Williams syndrome.

Several lines of investigation suggest that individuals with Williams syndrome (WS), a neurodevelopmental disorder of well-characterized genetic etiology, have selective impairments in integrating local image elements into global configurations. We compared global processing abilities in 10 clinically and genetically diagnosed participants with WS (eight females, two males; mean age 31y 10mo [SD 9y 7mo], range 15y 5mo-48y 4mo) with a typically developed (TD) age- and sex-matched comparison group (seven females, one male; mean age 35y 2mo [SD 10y 10mo], range 24y-54y 7mo) using functional magnetic resonance imaging (fMRI). Behavioral data showed participants with WS to be significantly less accurate (p<0.042) together with a non-significant trend to be slower than the TD comparison group while performing the global processing task. fMRI data showed participants with WS to possess reduced activation in the visual and parietal cortices. Participants with WS also showed relatively normal activation in the ventral occipitotemporal cortex, but elevated activation in several posterior thalamic nuclei. These preliminary results largely confirm previous research findings and neural models implicating neurodevelopmental abnormalities in extended subcortical and cortical visual systems in WS, most notably dorsal-stream pathways.

Analysis of infant carrying in large, well-established family groups of captive marmosets (Callithrix jacchus).

To assess the pattern of infant carrying across time and family members, we counted which animals in 13 well-established family groups of captive-bred marmosets (Callithrix jacchus) carried neonates during the first 8 weeks of life. The neonates were carried almost continuously for the first 3 weeks and then spent progressively more time independently. The mother did most of the carrying for the first 2 weeks, her contribution rising from day 1 to day 3 and declining thereafter. The contribution of the father was high on day 1, declined during the first week, and then rose to a peak in the fourth week. The contribution of the siblings rose sharply during the first week and declined thereafter. There was no overall difference in amount of infant carrying by each parent. The contribution of each sibling was small although in these large families the total contribution by siblings was large. These data may differ from previous observations because the breeding pairs were very well established, the families were large, and all except the youngest animals were very experienced in rearing and carrying. These data emphasise the group-dynamic nature of infant carrying in a primate species.