Anna Weighall

Consolidation of vocabulary is associated with sleep in children

Although the acquisition of a novel word is apparently rapid, adult research suggests that integration of novel and existing knowledge (measured by engagement in lexical competition) requires sleep-associated consolidation. We present the first investigation of whether a similar time-course dissociation characterizes word learning across development. Consistent with previous research but counter to adults, 7-12-year-olds showed sleep-associated consolidation effects in declarative but not procedural memory. Nevertheless, the relationship between sleep and word learning in children was remarkably similar to the pattern for adults. Following exposure to nonword competitors (e.g. biscal) in the a.m. or p.m., childrens ability to recognize and recall the nonwords improved only after sleep (after approximately 12-hrs for the p.m. group and 24-hrs for the a.m. group), with performance stable 1 week later. Novel nonwords only induced lexical competition effects after sleep. These findings suggest that children utilize a dual memory system when acquiring and integrating new vocabulary and highlight sleep as integral to this process. A video abstract of this article can be viewed at http://www.youtube.com/watch?feature=youtube_gdata&v=2UNuKCAakOk&gl=GB.

Learning new vocabulary during childhood: Effects of semantic training on lexical consolidation and integration

Research suggests that word learning is an extended process, with offline consolidation crucial for the strengthening of new lexical representations and their integration with existing lexical knowledge (as measured by engagement in lexical competition). This supports a dual memory systems account, in which new information is initially sparsely encoded separately from existing knowledge and integrated with long-term memory over time. However, previous studies of this type exploited unnatural learning contexts, involving fictitious words in the absence of word meaning. In this study, 5- to 9-year-old children learned real science words (e.g., hippocampus) with or without semantic information. Children in both groups were slower to detect pauses in familiar competitor words (e.g., hippopotamus) relative to control words 24h after training but not immediately, confirming that offline consolidation is required before new words are integrated with the lexicon and engage in lexical competition. Children recalled more new words 24h after training than immediately (with similar improvements shown for the recall and recognition of new word meanings); however, children who were exposed to the meanings during training showed further improvements in recall after 1 week and outperformed children who were not exposed to meanings. These findings support the dual memory systems account of vocabulary acquisition and suggest that the association of a new phonological form with semantic information is critical for the development of stable lexical representations.

Enhanced recognition and recall of new words in 7- and 12-year-olds following a period of offline consolidation.

Recent studies of adults have found evidence for consolidation effects in the acquisition of novel words, but little is known about whether such effects are found developmentally. In two experiments, we familiarized children with novel nonwords (e.g., biscal) and tested their recognition and recall of these items. In Experiment 1, 7-year-olds were then retested on either the same day or the following day to examine changes in performance after a short delay compared with a longer delay that included sleep. Experiment 2 used two age groups (7- and 12-year-olds), with all participants being retested 24h later. The 12-year-olds accurately recognized the novel nonwords immediately after exposure, as did the 7-year-olds in Experiment 2 (but not in Experiment 1), suggesting generally good initial rates of learning. Experiment 1 revealed improved recognition of the novel nonwords after both short (3- to 4-h) and longer (24-h) delays. In contrast, recall was initially poor but showed improvements only when children were retested 24h later, not after a 3- to 4-h delay. Similar improvements were observed in both age groups despite better overall performance in 12-year-olds. We argue that children, like adults, exhibit offline consolidation effects on the formation of novel phonological representations.

The role of working memory and contextual constraints in children's processing of relative clauses

An auditory sentence comprehension task investigated the extent to which the integration of contextual and structural cues was mediated by verbal memory span with 32 English-speaking six- to eight-year-old children. Spoken relative clause sentences were accompanied by visual context pictures which fully (depicting the actions described within the relative clause) or partially (depicting several referents) met the pragmatic assumptions of relativization. Comprehension of the main and relative clauses of centre-embedded and right-branching structures was compared for each context. Pragmatically appropriate contexts exerted a positive effect on relative clause comprehension, but children with higher memory spans demonstrated a further benefit for main clauses. Comprehension for centre-embedded main clauses was found to be very poor, independently of either context or memory span. The results suggest that children have access to adult-like linguistic processing mechanisms, and that sensitivity to extralinguistic cues is evident in young children and develops as cognitive capacity increases.

Graphic imagery is not sufficient for increased attention to cigarette warnings: the role of text captions

AIMS The present study aims to assess the extent to which attention to UK cigarette warnings is attributable to the graphic nature of the content. DESIGN A visual dot probe task was utilised, with the warnings serving as critical stimuli that were manipulated for the presence of graphic versus neutral image content, and the accompanying text caption. This mixed design yielded image content (graphic versus neutrally-matched images) and presence (versus absence) of text caption as within subjects variables and smoking status as a between-participants variable. SETTING The experiment took place within the laboratories of a UK university. PARTICIPANTS Eighty-six psychology undergraduates (51% smokers, 69% female), predominantly of Caucasian ethnicity took part. MEASUREMENTS Reaction times towards probes replacing graphic images relative to probes replacing neutral images were utilised to create an index of attentional bias. FINDINGS Bias scores (M = 10.20 ± 2.56) highlighted that the graphic image content of the warnings elicited attentional biases (relative to neutral images) for smokers. This only occurred in the presence of an accompanying text caption [t (43) = 3.950, P < 0.001] as opposed to when no caption was present [t (43) = 0.029, P = 0.977]. Non-smokers showed no biases in both instances. CONCLUSIONS Graphic imagery on cigarette packets increases attentional capture, but only when accompanied by a text message about health risks.

Eye-tracking the time-course of novel word learning and lexical competition in adults and children.

HighlightsNewly learned spoken words can compete for recognition soon after learning.Lexical competition effects were smaller for newly learned than existing words.Explicit memory was superior for words learned the day before testing.The sleep advantage for explicit memory correlated with sleep‐spindle density.Word learning seems boosted by sleep to a greater degree in children than adults. Abstract Lexical competition is a hallmark of proficient, automatic word recognition. Previous research suggests that there is a delay before a new spoken word becomes engaged in this process, with sleep playing an important role. However, data from one method – the visual world paradigm – consistently show competition without a delay. We trained 42 adults and 40 children (aged 7–8) on novel word‐object pairings, and employed this paradigm to measure the time‐course of lexical competition. Fixations to novel objects upon hearing existing words (e.g., looks to the novel object biscal upon hearing “click on the biscuit”) were compared to fixations on untrained objects. Novel word‐object pairings learned immediately before testing and those learned the previous day exhibited significant competition effects, with stronger competition for the previous day pairings for children but not adults. Crucially, this competition effect was significantly smaller for novel than existing competitors (e.g., looks to candy upon hearing “click on the candle”), suggesting that novel items may not compete for recognition like fully‐fledged lexical items, even after 24 h. Explicit memory (cued recall) was superior for words learned the day before testing, particularly for children; this effect (but not the lexical competition effects) correlated with sleep‐spindle density. Together, the results suggest that different aspects of new word learning follow different time courses: visual world competition effects can emerge swiftly, but are qualitatively different from those observed with established words, and are less reliant upon sleep. Furthermore, the findings fit with the view that word learning earlier in development is boosted by sleep to a greater degree.

Consolidation of vocabulary during sleep: The rich get richer?

HighlightsDifferent neural mechanisms may support word learning in children and adults.Children show larger proportions of slow‐wave sleep that supports consolidation.Consolidation in adults can benefit from richer existing knowledge.Meta‐analysis suggests extant vocabulary is associated with new word consolidation.Directions for uncovering prior knowledge influences on consolidation are proposed. ABSTRACT Sleep plays a role in strengthening new words and integrating them with existing vocabulary knowledge, consistent with neural models of learning in which sleep supports hippocampal transfer to neocortical memory. Such models are based on adult research, yet neural maturation may mean that the mechanisms supporting word learning vary across development. Here, we propose a model in which children may capitalise on larger amounts of slow‐wave sleep to support a greater demand on learning and neural reorganisation, whereas adults may benefit from a richer knowledge base to support consolidation. Such an argument is reinforced by the well‐reported “Matthew effect”, whereby rich vocabulary knowledge is associated with better acquisition of new vocabulary. We present a meta‐analysis that supports this association between childrens existing vocabulary knowledge and their integration of new words overnight. Whilst multiple mechanisms likely contribute to vocabulary consolidation and neural reorganisation across the lifespan, we propose that contributions of existing knowledge should be rigorously examined in developmental studies. Such research has potential to greatly enhance neural models of learning.

A systematic review of cognitive function and psychosocial well-being in school-age children with narcolepsy

In August 2010, concerns were raised about an increase in the incidence rate of narcolepsy diagnosis in children and adolescents. Narcolepsy is a chronic neurological sleep disorder characterised by excessive daytime sleepiness and attacks of muscle weakness which are often precipitated by strong emotions, known as cataplexy. We systematically examined and updated the scientific literature on the consequences of narcolepsy on cognitive function and psychosocial well-being in school-age children. Eight studies published between 2005 and 2015 were eligible for inclusion in this review. Collectively the results provide evidence to suggest that children who develop narcolepsy are at significant risk of cognitive impairment in at least one domain and emotional problems including depression, anxiety and low self-esteem. Children with narcolepsy should be monitored carefully in order to manage and reduce the impact of any impairments present. The existing literature is limited by small sample sizes, lack of appropriate controls and lack of longitudinal data. Future research should aim to address the limitations of the current work and aim to determine the underlying cause of cognitive and psychological impairments. This will enable the design of effective interventions to support children with narcolepsy so that they are able to achieve their full potential.

Consolidation of vocabulary is associated with sleep in typically developing children, but not in children with dyslexia

Sleep is known to play an active role in consolidating new vocabulary in adults; however, the mechanisms by which sleep promotes vocabulary consolidation in childhood are less well understood. Furthermore, there has been no investigation into whether previously reported differences in sleep architecture might account for variability in vocabulary consolidation in children with dyslexia. Twenty-three children with dyslexia and 29 age-matched typically developing peers were exposed to 16 novel spoken words. Typically developing children showed overnight improvements in novel word recall; the size of the improvement correlated positively with slow wave activity, similar to previous findings with adults. Children with dyslexia showed poorer recall of the novel words overall, but nevertheless showed overnight improvements similar to age-matched peers. However, comparisons with younger children matched on initial levels of novel word recall pointed to reduced consolidation in dyslexics after 1 week. Crucially, there were no significant correlations between overnight consolidation and sleep parameters in the dyslexic group. This suggests a reduced role of sleep in vocabulary consolidation in dyslexia, possibly as a consequence of lower levels of learning prior to sleep, and highlights how models of sleep-associated memory consolidation can be usefully informed by data from typical and atypical development.