Phonological loop and central executive contributions to oral comprehension skills of 5.5 to 9.5 years old children

Oral story comprehension in 5.5, 7.5 and 9.5 year old children is examined in relation to working memory (WM) contributions. The phonological loop (PL) of the Baddeley and Hitch WM model was assessed with word, non‐word and digit recall and a word list matching task. The central executive (CE) was assessed with listening, counting and backward digit recall tasks. A composite score was calculated for each WM component. Receptive vocabulary and oral comprehension were also assessed. Regression analyses demonstrated CE contributions to oral comprehension overall, and also to comprehension sub‐skills (above any vocabulary contributions). Effects were stronger in preschoolers and decreased with age. The PL did not play an important role in oral comprehension. Comprehension control was the comprehension skill best predicted. The study demonstrates the CE importance in off‐line comprehension processes during early childhood and the usefulness of assessing CE processes for identifying possible comprehension difficulties later at school. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of impoverished environmental conditions on working memory performance

This cross-cultural study investigates the impact of background experience on four verbal and visuo-spatial working memory (WM) tasks. A total of 84 children from low-income families were recruited from the following groups: (1) Portuguese immigrant children from Luxembourg impoverished in terms of language experience; (2) Brazilian children deprived in terms of scholastic background; (3) Portuguese children from Portugal with no disadvantage in either scholastic or language background. Children were matched on age, gender, fluid intelligence, and socioeconomic status and completed four simple and complex span tasks of WM and a vocabulary measure. Results indicate that, despite large differences in their backgrounds and language abilities, the groups exhibited comparable performance on the visuo-spatial tasks dot matrix and odd-one-out and on the verbal simple span task digit recall. Group differences emerged on the verbal complex span task counting recall with children from Luxembourg and Portugal outperforming children from disadvantaged schools in Brazil. The study suggests that whereas contributions of prior knowledge to digit span, dot matrix, and odd-one-out are likely to be minimal, background experience can affect performance on counting recall. Implications for testing WM capacity in children growing up in poverty are discussed.     

Impact of auditory selective attention on verbal short-term memory and vocabulary development

This study investigated the role of auditory selective attention capacities as a possible mediator of the well-established association between verbal short-term memory (STM) and vocabulary development. A total of 47 6- and 7-year-olds were administered verbal immediate serial recall and auditory attention tasks. Both task types probed processing of item and serial order information because recent studies have shown this distinction to be critical when exploring relations between STM and lexical development. Multiple regression and variance partitioning analyses highlighted two variables as determinants of vocabulary development: (a) a serial order processing variable shared by STM order recall and a selective attention task for sequence information and (b) an attentional variable shared by selective attention measures targeting item or sequence information. The current study highlights the need for integrative STM models, accounting for conjoined influences of attentional capacities and serial order processing capacities on STM performance and the establishment of the lexical language network.     

Relations between vocabulary development and verbal short-term memory: The relative importance of short-term memory for serial order and item information

Although many studies have shown an association between verbal short-term memory (STM) and vocabulary development, the precise nature of this association is not yet clear. The current study reexamined this relation in 4- to 6-year-olds by designing verbal STM tasks that maximized memory for either item or serial order information. Although empirical data suggest that distinct STM processes determine item and serial order recall, these were generally confounded in previous developmental studies. We observed that item and order memory tasks were independently related to vocabulary development. Furthermore, vocabulary development was more strongly associated with STM for order information in 4- and 6-year-olds and with STM for item information in 5-year-olds. These data highlight the specificity of verbal STM for serial order and item information and suggest a causal association between order STM processes and vocabulary development, at least in 4- and 6-year-olds.     

Interactions between working memory and language in young children with specific language impairment (SLI)

The underlying structure of working memory (WM) in young children with and without specific language impairment (SLI) was examined. The associations between the components of WM and the language abilities of young children with SLI were then analyzed. The Automated Working Memory Assessment and four linguistic tasks were administered to 58 children with SLI and 58 children without SLI, aged 4–5 years. The WM of the children was best represented by a model with four separate but interacting components of verbal storage, visuospatial storage, verbal central executive (CE), and visuospatial CE. The associations between the four components of WM did not differ significantly for the two groups of children. However, the individual components of WM showed varying associations with the language abilities of the children with SLI. The verbal CE component of WM was moderately to strongly associated with all the language abilities in children with SLI: receptive vocabulary, expressive vocabulary, verbal comprehension, and syntactic development. These results show verbal CE to be involved in a wide range of linguistic skills; the limited ability of young children with SLI to simultaneously store and process verbal information may constrain their acquisition of linguistic skills. Attention should thus be paid to the language problems of children with SLI, but also to the WM impairments that can contribute to their language problems.     

Phonological short‐term memory and vocabulary development: further evidence on the nature of the relationship

The nature and generality of the developmental association between phonological short‐term memory and vocabulary knowledge was explored in two studies. Study 1 investigated whether the link between vocabulary and verbal memory arises from the requirement to articulate memory items at recall or from earlier processes involved in the encoding and storage of the verbal material. Four‐year‐old children were tested on immediate memory measures which required either spoken recall (nonword repetition and digit span) or recognition of a sequence of nonwords. The phonological memory–vocabulary association was found to be as strong for the serial recognition as recall‐based measures, favouring the view that it is phonological short‐term memory capacity rather than speech output skills which constrain word learning. In Study 2, the association between phonological memory skills and vocabulary knowledge was found to be strong in teenaged as well as younger children, indicating that phonological memory constraints on word learning remain significant throughout childhood. Copyright © 1999 John Wiley & Sons, Ltd.     

Working memory contributions to reading comprehension components in middle childhood children

This study examined working memory contributions to reading comprehension subskills in Greek children (mean age 9 years, 1 month). The phonological loop of the Baddeley and Hitch working memory model was assessed with 3 recall tasks (words, nonwords, and digits) and a word list matching task. The central executive (CE) was assessed with 3 tasks (listening, counting, and backward digit recall). Participants were also given a receptive vocabulary task, a reading fluency task, and written stories accompanied by comprehension questions. Canonical correlation analyses showed that the comprehension variables were related to the CE rather than the phonological loop measures. CE functions were more strongly associated with elaborative inference generation (involving significant offline processing) and comprehension control (involving metacognitive monitoring). Smaller yet significant associations were observed between the CE and the necessary inference and literal comprehension measures, whereas a moderate relationship was found in the case of the simile comprehension variable. Among the CE variables, listening recall demonstrated the highest loading on the canonical function, followed by moderate yet significant counting and backward digit recall loadings. Vocabulary was found to fully mediate several associations between working memory and comprehension measures; however, the relationship between listening recall and elaborative inferences was partly mediated. Reading fluency and, on several occasions, Greek vocabulary knowledge did not mediate the relationships between CE measures and comprehension skills assessed. This study demonstrates the usefulness of CE measures for identifying young children's possible difficulties in carrying out specific reading comprehension processes.     

Working Memory and Cognitive Skills in Individuals with Down Syndrome

This work is aimed at analyzing working memory (WM) components and their relationships with other cognitive processes in individuals with Down syndrome (DS). Particular attention is given to examine whether a verbal WM deficit is due to difficulties in verbal abilities often showed by individuals with DS, or whether it is a deficit per se. A group of 20 individuals with DS was compared to a group of 20 typically developing (TD) children matched on vocabulary comprehension and to a group of 20 TD children matched on general verbal intelligence. The groups received a battery of 3 verbal and 3 visuospatial WM tasks requiring different degrees of control, and tests assessing verbal abilities (WPPSI verbal scale, PPVT), nonverbal skills (WPPSI performance scale), and logical thinking (LO). The results revealed that individuals with DS have deficits in both central executive (control) and verbal components of the WM system, and the latter one is independent of the general verbal abilities deficit. The data suggest that the development of central executive proceeds at a slower rate in individuals with DS and differently from TD children with comparable verbal abilities. The performance of individuals with DS on high-control WM tasks requires additional general resources that are strictly linked to intelligence.     

Speech timing and working memory in profoundly deaf children after cochlear implantation

Thirty-seven profoundly deaf children between 8- and 9-years-old with cochlear implants and a comparison group of normal-hearing children were studied to measure speaking rates, digit spans, and speech timing during digit span recall. The deaf children displayed longer sentence durations and pauses during recall and shorter digit spans compared to the normal-hearing children. Articulation rates, measured from sentence durations, were strongly correlated with immediate memory span in both normal-hearing and deaf children, indicating that both slower subvocal rehearsal and scanning processes may be factors that contribute to the deaf children's shorter digit spans. These findings demonstrate that subvocal verbal rehearsal speed and memory scanning processes are not only dependent on chronological age as suggested in earlier research by. Instead, in this clinical population the absence of early auditory experience and phonological processing activities before implantation appears to produce measurable effects on the working memory processes that rely on verbal rehearsal and serial scanning of phonological information in short-term memory.     

When meaning is useless

The aim of this study is to disentangle the relative contribution of semantic and phonological representation in immediate serial recall. Indeed, short-term memory (STM) performance could be enhanced by familiarity with the phonological form of the word only or together with semantic information. Participants learned two sets of words in an unknown language: for one set they acquired both phonology and semantics, while for the other only phonology. After that, they performed two immediate serial recall tasks involving either “phonology and semantics” or “only phonology” words and one with untrained words. The analyses showed that the trained lists did not differ from each other, while they did from the untrained one. These data confirm that familiarity with the phonological form is sufficient for immediate serial recall. Therefore, we argue that semantics is not required for verbal STM, but knowledge of the phonological form is what matters.     

Lexical coherence in short-term memory: Strategic reconstruction or “semantic glue”?

This study explores the foundation of lexical/semantic phoneme binding effects in verbal short-term memory (STM). The immediate serial recall of pure lists of words and nonwords was compared with the recall of mixed lists that had either a predictable, alternating structure (e.g., wnwnwn) or an unpredictable structure (i.e., the serial positions of the words/nonwords could not be known in advance). The study provides evidence for two separate mechanisms by which long-term linguistic knowledge contributes to STM. First, there was evidence for automatic lexical/semantic binding effects that were independent of knowledge of lexical status. The nonwords in both types of mixed list damaged word recall and encouraged the phonological elements of words to migrate. In both alternating and unpredictable mixed lists, the phonemes of words were more likely than the phonemes of nonwords to be recalled together as a coherent item, suggesting that lexical/semantic knowledge encourages the phonological elements of words to emerge together in immediate serial recall, even when lexical status is unknown. Secondly, there was evidence for “strategic redintegration”, which was dependent on prior knowledge of the lexical status of the items in mixed lists. When participants recalled items that they knew to be words in advance, they were able to use this knowledge to constrain their responses so that they were more likely to be lexically appropriate. These findings motivate modifications to current theories of the interaction between linguistic knowledge and verbal short-term memory.     

Growth in working memory and inhibition predicts literacy in English language learners: A cross-sectional and longitudinal study

The purpose of this study was to determine whether cross-sectional and growth effects in second language (L2) literacy are related to the executive component of working memory (WM) and whether inhibition may underlie the links between WM and reading in children whose first language (L1) is Spanish. Elementary school children (grades 1, 2 and 3) were administered a battery of cognitive [WM, short-term memory (STM), random generation, rapid naming, phonological processing], vocabulary and reading measures in both Spanish (L1) and English (L2) in Year 1 and again one year later. The regression analyses showed that L2 growth in WM significantly predicted growth in L2 reading skills even when inhibition was controlled. Further, the contributions of WM to reading growth in both L1 and L2 reading were independent of cross-language skills in phonological processing, STM, oral language and naming speed. Overall, the results suggest the mental activities that underlie WM and inhibition in predictions of L2 literacy reflect independent executive processes.     

Precision of working memory for speech sounds

Memory for speech sounds is a key component of models of verbal working memory (WM). But how good is verbal WM? Most investigations assess this using binary report measures to derive a fixed number of items that can be stored. However, recent findings in visual WM have challenged such “quantized” views by employing measures of recall precision with an analogue response scale. WM for speech sounds might rely on both continuous and categorical storage mechanisms. Using a novel speech matching paradigm, we measured WM recall precision for phonemes. Vowel qualities were sampled from a formant space continuum. A probe vowel had to be adjusted to match the vowel quality of a target on a continuous, analogue response scale. Crucially, this provided an index of the variability of a memory representation around its true value and thus allowed us to estimate how memories were distorted from the original sounds. Memory load affected the quality of speech sound recall in two ways. First, there was a gradual decline in recall precision with increasing number of items, consistent with the view that WM representations of speech sounds become noisier with an increase in the number of items held in memory, just as for vision. Based on multidimensional scaling (MDS), the level of noise appeared to be reflected in distortions of the formant space. Second, as memory load increased, there was evidence of greater clustering of participants' responses around particular vowels. A mixture model captured both continuous and categorical responses, demonstrating a shift from continuous to categorical memory with increasing WM load. This suggests that direct acoustic storage can be used for single items, but when more items must be stored, categorical representations must be used.     

New Word Acquisition in Children: Examining the Contribution of Verbal Short‐term Memory to Lexical and Semantic Levels of Learning

A variety of evidence suggests that human vocabulary acquisition and verbal short‐term ability are related. The aim of this study was to investigate the learning of new lexical and semantic representation in 7 to 12 years old children selected on the basis of their poor working memory capacity. A deep characterization of the short‐term memory (STM) capacities has been carried out through a series of tasks derived from recent STM models tapping STM, language and attentional processes. Participants experienced a three conditions word learning task designed to reflect lexical learning, semantic learning and lexical–semantic learning capacities. Other aspects of the learning such as the learning rate and the word length effect were evaluated. The experimental participants scored more poorly than controls on lexical learning, and this deficit was associated with the serial order STM and the attentional capacities. The current study also highlighted that neither the experimental group nor the control group took advantage in lexical learning of semantic information supplement. Our results suggest that children with verbal STM problems learn a smaller number of new words but present a similar way of learning than children without verbal STM problems. Copyright © 2013 John Wiley & Sons, Ltd.     

Music Training and Semantic Clustering in College Students

College students with 5 or more years of music training recalled significantly more words from a 16-item word list than did students with 0-4 years of training. The superior recall of the extensively trained students linked to better application of a semantic-clustering strategy across a series of 3 test trials. Music education and language experience may have similar influences on the development of verbal memory.     

Phonotactic probability effect in nonword recall and its relationship with vocabulary in monolingual and bilingual preschoolers

The current study examined to what extent information in long-term memory concerning the distribution of phoneme clusters in a language, so-called long-term phonotactic knowledge, increased the capacity of verbal short-term memory in young language learners and, through increased verbal short-term memory capacity, supported these children’s first and second language vocabulary acquisition. Participants were 67 monolingual Dutch and 60 bilingual Turkish–Dutch 4-year-olds. The superior recall of nonwords with high phonotactic probability compared with nonwords with low phonotactic probability indicated that phonotactic knowledge was supportive for verbal short-term recall in both languages. The extent of this support depended on prior experiences with the language: The Turkish–Dutch children showed a greater phonotactic probability effect in their native language Turkish compared with their Dutch peers, and the monolingual Dutch children outperformed the bilingual Turkish–Dutch children in their native language Dutch. Regression analyses showed that phonotactic knowledge, indicated by the difference in recall of nonwords with high versus low phonotactic probability, was an important predictor of vocabulary in both languages.     

Internalising symptoms and verbal working memory in school‐age children: A processing efficiency analysis

The current study investigated differential contributions of internalising symptoms (state anxiety, trait anxiety, depression) to school‐age children's verbal short‐term (STM) and working memory (WM) span accuracy and efficiency (microanalysis of response times). Children's (N = 125, M_age = 11.44 years) STM/WM was assessed with simple/complex span tasks. Our analyses revealed that: (a) children with high levels of state anxiety displayed reduced simple span accuracy (on Word span) and poorer efficiency on both simple (preparatory intervals, interword pauses) and complex span (preparatory intervals) response time segments; (b) trait anxiety was a negative predictor of children's complex span accuracy, as well as their efficiency on both simple (word durations) and complex span (interword pauses) response time measures; (3) depressive symptoms predicted longer simple span interword pauses. Findings indicate that while all internalising symptoms were predictive of children's poorer memory search efficiency, especially during the “silent”, executive intervals (interword pauses), anxiety symptoms were specifically predictive of children's impaired span accuracy and other efficiency indicators (preparatory intervals, word durations). The study highlights the differential contributions of state, trait anxiety, and depressive symptoms to STM/WM in children, emphasising the need to measure both accuracy and efficiency to assess the role that such symptoms play in children's performance.     

Episodic and semantic memory in bilingual and monolingual children

Although bilinguality has been reported to confer advantages upon children with respect to various cognitive abilities, much less is known about the relation between memory and bilinguality. In this study, 60 (30 girls and 30 boys) bilingual and 60 (30 girls and 30 boys) monolingual children in three age groups (mean ages 8.5, 10.5 and 12.5 years) were compared on episodic memory and semantic memory tasks. Episodic memory was assessed using subject-performed tasks (with real or imaginary objects) and verbal tasks, with retrieval by both free recall and cued recall. Semantic memory was assessed by word fluency tests. Positive effects of bilingualism were found on both episodic memory and semantic memory at all age levels. These findings suggest that bilingual children integrate and/or organize the information of two languages, and so bilingualism creates advantages in terms of cognitive abilities (including memory). Some sex differences were also found in episodic memory but not in semantic memory. This episodic memory difference was found with younger children.     

Short-Term Memory and Working Memory in Children with Blindness: Support for a Domain General or Domain Specific System?

The study explored the contribution of two component processes (phonological and executive) to blind children's memory performance. Children with blindness and sight were matched on gender, chronological age, and verbal intelligence and compared on measures of short-term memory (STM) and working memory (WM). Although the measures were highly correlated, the results from two experiments indicated that the blind children were superior to sighted children on measures of STM, but not on measures of WM. The results supported the notion that children with blindness have advantages on memory tasks that draw upon resources from the phonological loop. However, comparable performance between the ability groups on WM measures suggests there are domain specific aspects in the executive system.     

Specific conditions for a selective deficit in memory for order in children with dyslexia

Short-term memory (STM) models distinguish between item and order memorization. The present study aims to explore how item and order STM are affected by the nature of the stimuli, the sequential versus simultaneous mode of presentation, the visual versus auditory presentation modality, the possibility of verbal recoding. A total of 20 children with dyslexia were matched one-by-one with 20 typically reading children on sex, age (8–14 years), and grade. Computerized STM tasks were administered while manipulating type (item vs. order), stimuli (letters vs. colors), sequentiality, input and output modality, as well as the presence/absence of articulatory suppression and distractors. General Linear Model analyses were conducted on accuracy scores for item and order STM. Both item and order recall scores were lower for children with dyslexia. Although order STM in the visual input condition turned out to be more impaired than item STM in the dyslexic group, both item and order memory impairments become evident when verbal recoding is prevented through articulatory suppression. Moreover, dyslexic children, unlike typical readers, were not facilitated by the linguistic nature of the stimuli to be remembered. The present findings suggest that the often-reported selective impairment of serial memory in dyslexia is restricted to stimuli that are verbal in nature or can be verbally recoded, whereas both item and order memory impairments become evident when verbal recoding is prevented through articulatory suppression. The presence of distractors is particularly detrimental to STM in the dyslexic group. The sensitivity to distractors, suppression, and stimuli in STM is predictive of reading performance.