Mothers used wider vocabulary and talked to their six-month-old infants more during shared book reading than when they played with toys.

AIM: We compared mothers reading books to six-month-old infants or playing with toys and measured whether the maternal language input influenced the children's spoken vocabulary at 18 months of age. METHOD: This Taiwanese study recruited 46 dyads and video recorded them while the mothers read books to their infants and played with them with toys at 6 months of age. The mothers' lexical diversity, which is the ratio of different unique words to the total number of words, was measured. We then assessed the children's spoken vocabulary at 18 months. RESULTS: The mother used more diverse vocabulary and a higher number of words when they were reading books than playing with toys with their children (p = 0.001). Maternal lexical diversity at 6 months of age accounted for 14.4% of the unique variance in the number of different words used by the child at 18 months. We believe that this is a novel finding. CONCLUSION: Mothers used wider vocabulary and talked to their infants more during book reading than when they played with toys. Diverse maternal vocabulary at 6 months of age positively influenced the number of different words their children used at 18 months of age.

Predictive brain signals mediate association between shared reading and expressive vocabulary in infants.

The ability to predict upcoming information is crucial for efficient language processing and enables more rapid language learning. The present study explored how shared reading experience influenced predictive brain signals and expressive vocabulary of 12-month-old infants. The predictive brain signals were measured by fNIRS responses in the occipital lobe with an unexpected visual-omission task. The amount of shared reading experience was correlated with the strength of this predictive brain signal and with infants' expressive vocabulary. Importantly, the predictive brain signal explained unique variance of expressive vocabulary beyond shared reading experience and maternal education. A further mediation analysis showed that the effect of shared reading experience on expressive vocabulary was explained by the infants' predictive brain signal. This is the first evidence indicating that richer shared reading experience strengthens predictive signals in the infant brain and in turn facilitates expressive vocabulary acquisition.

Top-down sensory prediction in the infant brain at 6 months is correlated with language development at 12 and 18 months.

Previous research has suggested that top-down sensory prediction facilitates, and may be necessary for, efficient transmission of information in the brain. Here we related infants' vocabulary development to the top-down sensory prediction indexed by occipital cortex activation to the unexpected absence of a visual stimulus previously paired with an auditory stimulus. The magnitude of the neural response to the unexpected omission of a visual stimulus was assessed at the age of 6 months with functional near-infrared spectroscopy (fNIRS) and vocabulary scores were obtained using the MacArthur-Bates Communicative Development Inventory (MCDI) when infants reached the age of 12 months and 18 months, respectively. Results indicated significant positive correlations between this predictive neural signal at 6 months and MCDI expressive vocabulary scores at 12 and 18 months. These findings provide additional and robust support for the hypothesis that top-down prediction at the neural level plays a key role in infants' language development.

Cross-modal working memory binding and word recognition skills: how specific is the link?

Recent research has suggested that the creation of temporary bound representations of information from different sources within working memory uniquely relates to word recognition abilities in school-age children. However, it is unclear to what extent this link is attributable specifically to the binding ability for cross-modal information. This study examined the performance of Grade 3 (8-9 years old) children on binding tasks requiring either temporary association formation of two visual items (i.e., within-modal binding) or pairs of visually presented abstract shapes and auditorily presented nonwords (i.e., cross-modal binding). Children's word recognition skills were related to performance on the cross-modal binding task but not on the within-modal binding task. Further regression models showed that cross-modal binding memory was a significant predictor of word recognition when memory for its constituent elements, general abilities, and crucially, within-modal binding memory were taken into account. These findings may suggest a specific link between the ability to bind information across modalities within working memory and word recognition skills.

Cross-modal working memory binding and L1-L2 word learning.

The ability to create temporary binding representations of information from different sources in working memory has recently been found to relate to the development of monolingual word recognition in children. The current study explored this possible relationship in an adult word-learning context. We assessed whether the relationship between cross-modal working memory binding and lexical development would be observed in the learning of associations between unfamiliar spoken words and their semantic referents, and whether it would vary across experimental conditions in first- and second-language word learning. A group of English monolinguals were recruited to learn 24 spoken disyllable Mandarin Chinese words in association with either familiar or novel objects as semantic referents. They also took a working memory task in which their ability to temporarily bind auditory-verbal and visual information was measured. Participants' performance on this task was uniquely linked to their learning and retention of words for both novel objects and for familiar objects. This suggests that, at least for spoken language, cross-modal working memory binding might play a similar role in second language-like (i.e., learning new words for familiar objects) and in more native-like situations (i.e., learning new words for novel objects). Our findings provide new evidence for the role of cross-modal working memory binding in L1 word learning and further indicate that early stages of picture-based word learning in L2 might rely on similar cognitive processes as in L1.

Evaluating the developmental trajectory of the episodic buffer component of working memory and its relation to word recognition in children.

The creation of temporary bound representation of information from different sources is one of the key abilities attributed to the episodic buffer component of working memory. Whereas the role of working memory in word learning has received substantial attention, very little is known about the link between the development of word recognition skills and the ability to bind information in the episodic buffer of working memory and how it may develop with age. This study examined the performance of Grade 2 children (8 years old), Grade 3 children (9 years old), and young adults on a task designed to measure their ability to bind visual and auditory-verbal information in working memory. Children's performance on this task significantly correlated with their word recognition skills even when chronological age, memory for individual elements, and other possible reading-related factors were taken into account. In addition, clear developmental trajectories were observed, with improvements in the ability to hold temporary bound information in working memory between Grades 2 and 3, and between the child and adult groups, that were independent from memory for the individual elements. These findings suggest that the capacity to temporarily bind novel auditory-verbal information to visual form in working memory is linked to the development of word recognition in children and improves with age.

Interference control in children with reading difficulties.

Two studies investigated whether the greater Stroop interference reported in children with reading difficulties compared to typical readers of the same age represents a generalized deficit in interference control or a consequence of their reading problems. In Study 1, a color-word Stroop task and a nonverbal task involving responses to locations associated with pictures were administered to 23 children with single word reading difficulties and 22 typically developing children matched for age and nonverbal ability. Children with reading difficulties showed disproportionate interference effects in the color-word Stroop but not the nonverbal task. In Study 2, groups of poor and typical readers completed a spatial Stroop task with printed input that did not require a verbal response and a nonverbal analogue. Both groups showed comparable interference in these two tasks. Thus, the reported problems in the color-word Stroop task in children with reading difficulties do not appear to entail general impairments in interference control.

Working memory deficits in children with reading difficulties: memory span and dual task coordination.

The current study investigated the cause of the reported problems in working memory in children with reading difficulties. Verbal and visuospatial simple and complex span tasks, and digit span and reaction times tasks performed singly and in combination, were administered to 46 children with single word reading difficulties and 45 typically developing children matched for age and nonverbal ability. Children with reading difficulties had pervasive deficits in the simple and complex span tasks and had poorer abilities to coordinate two cognitive demanding tasks. These findings indicate that working memory problems in children with reading difficulties may reflect a core deficit in the central executive.