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

Improving working memory in children with low language abilities

This study investigated whether working memory training is effective in enhancing verbal memory in children with low language abilities (LLA). Cogmed Working Memory Training was completed by a community sample of children aged 8-11 years with LLA and a comparison group with matched non-verbal abilities and age-typical language performance. Short-term memory (STM), working memory, language, and IQ were assessed before and after training. Significant and equivalent post-training gains were found in visuo-spatial short-term memory in both groups. Exploratory analyses across the sample established that low verbal IQ scores were strongly and highly specifically associated with greater gains in verbal STM, and that children with higher verbal IQs made greater gains in visuo-spatial short-term memory following training. This provides preliminary evidence that intensive working memory training may be effective for enhancing the weakest aspects of STM in children with low verbal abilities, and may also be of value in developing compensatory strategies.

Order short-term memory is not impaired in dyslexia and does not affect orthographic learning

This article reports two studies that investigate short-term memory (STM) deficits in dyslexic children and explores the relationship between STM and reading acquisition. In the first experiment, 36 dyslexic children and 61 control children performed an item STM task and a serial order STM task. The results of this experiment show that dyslexic children do not suffer from a specific serial order STM deficit. In addition, the results demonstrate that phonological processing skills are as closely related to both item STM and serial order STM. However, non-verbal intelligence was more strongly involved in serial order STM than in item STM. In the second experiment, the same two STM tasks were administered and reading acquisition was assessed by measuring orthographic learning in a group of 188 children. The results of this study show that orthographic learning is exclusively related to item STM and not to order STM. It is concluded that serial order STM is not the right place to look for a causal explanation of reading disability, nor for differences in word reading acquisition.

Domain-specific and domain-general constraints on word and sequence learning

The relative influences of language-related and memory-related constraints on the learning of novel words and sequences were examined by comparing individual differences in performance of children with and without specific deficits in either language or working memory. Children recalled lists of words in a Hebbian learning protocol in which occasional lists repeated, yielding improved recall over the course of the task on the repeated lists. The task involved presentation of pictures of common nouns followed immediately by equivalent presentations of the spoken names. The same participants also completed a paired-associate learning task involving word-picture and nonword-picture pairs. Hebbian learning was observed for all groups. Domain-general working memory constrained immediate recall, whereas language abilities impacted recall in the auditory modality only. In addition, working memory constrained paired-associate learning generally, whereas language abilities disproportionately impacted novel word learning. Overall, all of the learning tasks were highly correlated with domain-general working memory. The learning of nonwords was additionally related to general intelligence, phonological short-term memory, language abilities, and implicit learning. The results suggest that distinct associations between language- and memory-related mechanisms support learning of familiar and unfamiliar phonological forms and sequences.

The effects of limited bandwidth and noise on verbal processing time and word recall in normal-hearing children

OBJECTIVES

Understanding speech in acoustically degraded environments can place significant cognitive demands on school-age children who are developing the cognitive and linguistic skills needed to support this process. Previous studies suggest the speech understanding, word learning, and academic performance can be negatively impacted by background noise, but the effect of limited audibility on cognitive processes in children has not been directly studied. The aim of the present study was to evaluate the impact of limited audibility on speech understanding and working memory tasks in school-age children with normal hearing.

DESIGN

Seventeen children with normal hearing between 6 and 12 years of age participated in the present study. Repetition of nonword consonant-vowel-consonant stimuli was measured under conditions with combinations of two different signal to noise ratios (SNRs; 3 and 9 dB) and two low-pass filter settings (3.2 and 5.6 kHz). Verbal processing time was calculated based on the time from the onset of the stimulus to the onset of the child's response. Monosyllabic word repetition and recall were also measured in conditions with a full bandwidth and 5.6 kHz low-pass cutoff.

RESULTS

Nonword repetition scores decreased as audibility decreased. Verbal processing time increased as audibility decreased, consistent with predictions based on increased listening effort. Although monosyllabic word repetition did not vary between the full bandwidth and 5.6 kHz low-pass filter condition, recall was significantly poorer in the condition with limited bandwidth (low pass at 5.6 kHz). Age and expressive language scores predicted performance on word recall tasks, but did not predict nonword repetition accuracy or verbal processing time.

CONCLUSIONS

Decreased audibility was associated with reduced accuracy for nonword repetition and increased verbal processing time in children with normal hearing. Deficits in free recall were observed even under conditions where word repetition was not affected. The negative effects of reduced audibility may occur even under conditions where speech repetition is not impacted. Limited stimulus audibility may result in greater cognitive effort for verbal rehearsal in working memory and may limit the availability of cognitive resources to allocate to working memory and other processes.

Short term memory for serial order: unraveling individual differences in the use of processes and changes across tasks

In this study we investigated whether we could distinguish the use of specific verbal and visual short term memory (STM) processes in children, or whether the differences in memory performance could be interpreted only in terms of quantitative differences. First, the number of processes involved in the responses on six STM tasks (serial order reconstruction) of 210 primary school children aged 5-12 years was examined by means of latent states. The number of items to reconstruct was manipulated to unravel quantitative differences in responses (high or low performance), and the similarity of the items was manipulated to distinguish qualitative differences in responses (verbal or visual processing). Furthermore, we examined how children changed from one type of process to another on tasks with list lengths of 3, 5, and 7 items by means of the dynamics between the latent states using a latent Markov model. The results showed that two latent states representing the use of specific verbal and visual STM processes could be distinguished on all the tasks. Moreover, two latent states showing merely differences in performance were also found. These findings underline the value of latent variable models to unravel differences between as well as within individuals in the use of cognitive processes.

Establishing the Reliability and Validity of a Computerized Assessment of Children’s Working Memory for Use in Group Settings

The aim of the present study was to investigate the reliability and validity of a brief standardized assessment of children’s working memory; Lucid Recall. Although there are many established assessments of working memory, Lucid Recall is fully automated and can therefore be administered in a group setting. It is therefore ideally suited to large-scale screening or research purposes. The findings indicated suitable test–retest reliability. Scores were also correlated with children’s scores on the Wechsler Intelligence Scale for Children–IV working memory subtests, scholastic attainment, and ratings of children’s working memory behaviors. Working memory scores also distinguished between children with and without special educational needs. The findings are discussed in terms of practical implications for practitioners.

Language repetition and short-term memory: an integrative framework

Short-term maintenance of verbal information is a core factor of language repetition, especially when reproducing multiple or unfamiliar stimuli. Many models of language processing locate the verbal short-term maintenance function in the left posterior superior temporo-parietal area and its connections with the inferior frontal gyrus. However, research in the field of short-term memory has implicated bilateral fronto-parietal networks, involved in attention and serial order processing, as being critical for the maintenance and reproduction of verbal sequences. We present here an integrative framework aimed at bridging research in the language processing and short-term memory fields. This framework considers verbal short-term maintenance as an emergent function resulting from synchronized and integrated activation in dorsal and ventral language processing networks as well as fronto-parietal attention and serial order processing networks. To-be-maintained item representations are temporarily activated in the dorsal and ventral language processing networks, novel phoneme and word serial order information is proposed to be maintained via a right fronto-parietal serial order processing network, and activation in these different networks is proposed to be coordinated and maintained via a left fronto-parietal attention processing network. This framework provides new perspectives for our understanding of information maintenance at the non-word-, word- and sentence-level as well as of verbal maintenance deficits in case of brain injury.

Impaired short-term memory for order in adults with dyslexia

Verbal short-term memory (STM) deficits are consistently associated with dyslexia, but the nature of these deficits remains poorly understood. This study used the distinction between item and order retention processes to achieve a better understanding of STM deficits in adults with dyslexia. STM for item information has been shown to depend on the quality of underlying phonological representations, and hence should be impaired in dyslexia, which is characterized by poorly developed phonological representations. On the other hand, STM for order information is considered to reflect core STM processes, which are independent from language processing. Thirty adults with dyslexia and thirty control participants matched for age, education, vocabulary, and IQ were presented STM tasks, which distinguished item and order STM capacities. We observed not only impaired order STM in adults with dyslexia, but this impairment was independent of item STM impairment. This study shows that adults with dyslexia present a deficit in core verbal STM processes, a deficit which cannot be accounted for by the language processing difficulties that characterize dyslexia. Moreover, these results support recent theoretical accounts considering independent order STM and item STM processes, with a potentially causal involvement of order STM processes in reading acquisition.

Cognitive abilities underlying second-language vocabulary acquisition in an early second-language immersion education context: a longitudinal study

First-language (L1) and second-language (L2) lexical development has been found to be strongly associated with phonological processing abilities such as phonological short-term memory (STM), phonological awareness, and speech perception. Lexical development also seems to be linked to attentional and executive skills such as auditory attention, flexibility, and response inhibition. The aim of this four-wave longitudinal study was to determine to what extent L2 vocabulary acquired through the particular school context of early L2 immersion education is linked to the same cognitive abilities. A total of 61 French-speaking 5-year-old kindergartners who had just been enrolled in English immersion classes were administered a battery of tasks assessing these three phonological processing abilities and three attentional/executive skills. Their English vocabulary knowledge was measured 1, 2, and 3 school years later. Multiple regression analyses showed that, among the assessed phonological processing abilities, phonological STM and speech perception, but not phonological awareness, appeared to underlie L2 vocabulary acquisition in this context of an early L2 immersion school program, at least during the first steps of acquisition. Similarly, among the assessed attentional/executive skills, auditory attention and flexibility, but not response inhibition, appeared to be involved during the first steps of L2 vocabulary acquisition in such an immersion school context.

Cross-linguistic and cross-cultural effects on verbal working memory and vocabulary: testing language-minority children with an immigrant background

PURPOSE

In this study, the authors explored the impact of test language and cultural status on vocabulary and working memory performance in multilingual language-minority children.

METHOD

Twenty 7-year-old Portuguese-speaking immigrant children living in Luxembourg completed several assessments of first (L1)- and second-language (L2) vocabulary (comprehension and production), executive-loaded working memory (counting recall and backward digit recall), and verbal short-term memory (digit recall and nonword repetition). Cross-linguistic task performance was compared within individuals. The language-minority children were also compared with multilingual language-majority children from Luxembourg and Portuguese-speaking monolinguals from Brazil without an immigrant background matched on age, sex, socioeconomic status, and nonverbal reasoning.

RESULTS

Results showed that (a) verbal working memory measures involving numerical memoranda were relatively independent of test language and cultural status; (b) language status had an impact on the repetition of high- but not on low-wordlike L2 nonwords; (c) large cross-linguistic and cross-cultural effects emerged for productive vocabulary; (d) cross-cultural effects were less pronounced for vocabulary comprehension with no differences between groups if only L1 words relevant to the home context were considered.

CONCLUSION

The study indicates that linguistic and cognitive assessments for language-minority children require careful choice among measures to ensure valid results. Implications for testing culturally and linguistically diverse children are discussed.

Evidence for a specific impairment of serial order short-term memory in dyslexic children

In order to better understand the nature of verbal short-term memory (STM) deficits in dyslexic children, the present study used the distinction between item and serial order retention capacities in STM tasks. According to recent STM models, storage of verbal item information depends very directly upon the richness of underlying phonological and semantic representations. On the other hand, storage of serial order information appears to reflect a language-independent system. Hence, if there is a fundamental STM deficit in dyslexia that is not to be explained only by the poor phonological processing abilities that characterize dyslexia, then difficulties in serial order STM should also be observed in dyslexic children. We administered tasks maximizing either serial order or item retention capacities to dyslexic children and reading age (RA) and chronological age (CA) matched controls. Dyslexic children performed significantly poorer than the CA controls on the item STM measure. Furthermore, the dyslexic group obtained inferior performance than both CA and RA control groups on the serial order STM measure. These findings highlight a severe impairment of STM for serial order information in dyslexia that cannot be reduced to a phonological processing impairment. Implications of serial order retention deficits for reading acquisition and dyslexia are discussed.

Effect of onset and rhyme primes in preschoolers with typical development and specific language impairment

PURPOSE

In this study, the authors used cued shadowing to examine children's phonological word-form representations by studying the effects of onset and rhyme primes on lexical access.

METHOD

Twenty-five preschoolers with specific language impairment (SLI; hereafter known as the SLI group), 24 age- and gender-matched children (AM group), and 20 vocabulary- and gender-matched children (VM group) participated. Children listened to pairs of words and repeated the second word as quickly as they could. Primes included words with overlapping onsets, words with overlapping rimes, and identical or unrelated words.

RESULTS

As expected, unrelated words inhibited production in the AM and VM groups. Overlapping rimes primed production in the AM group. No inhibitory or priming effects were found for the SLI group.

CONCLUSION

Phonological priming may be used to study the phonological representations of preschool-age children. Results suggest that none of the groups accessed words incrementally. Priming for overlapping rimes by the AM but not the VM or SLI groups may indicate that the AM group benefited from lexical organization favoring nucleus + rime organization that has not yet developed for the VM or SLI groups. The lack of inhibition in the SLI group suggests that their phonological representations were not detailed enough to prime words in their lexicon or that they did not process the prime or target words.

The relationship between vocabulary and short-term memory measures in monolingual and bilingual speakers

Previous studies have indicated that bilingualism may influence the efficiency of lexical access in adults. The goals of this research were (1) to compare bilingual and monolingual adults on their native-language vocabulary performance, and (2) to examine the relationship between short-term memory skills and vocabulary performance in monolinguals and bilinguals. In Experiment 1, English-speaking monolingual adults and simultaneous English-Spanish bilingual adults were administered measures of receptive English vocabulary and of phonological short-term memory. In Experiment 2, monolingual adults were compared to sequential English-Spanish bilinguals, and were administered the same measures as in Experiment 1, as well as a measure of expressive English vocabulary. Analyses revealed comparable levels of performance on the vocabulary and the short-term memory measures in the monolingual and the bilingual groups across both experiments. There was a stronger effect of digit-span in the bilingual group than in the monolingual group, with high-span bilinguals outperforming low-span bilinguals on vocabulary measures. Findings indicate that bilingual speakers may rely on short-term memory resources to support word retrieval in their native language more than monolingual speakers.

Searching for the Hebb effect in Down syndrome: evidence for a dissociation between verbal short-term memory and domain-general learning of serial order

BACKGROUND

The Hebb effect is a form of repetition-driven long-term learning that is thought to provide an analogue for the processes involved in new word learning. Other evidence suggests that verbal short-term memory also constrains now vocabulary acquisition, but if the Hebb effect is independent of short-term memory, then it may be possible to demonstrate its preservation in a sample of individuals with Down syndrome, who typically show a verbal short-term memory deficit alongside surprising relative strengths in vocabulary.

METHODS

In two experiments, individuals both with and without Down syndrome (matched for receptive vocabulary) completed immediate serial recall tasks incorporating a Hebb repetition paradigm in either verbal or visuospatial conditions.

RESULTS

Both groups demonstrated equivalent benefit from Hebb repetition, despite individuals with Down syndrome showing significantly lower verbal short-term memory spans. The resultant Hebb effect was equivalent across verbal and visuospatial domains.

CONCLUSIONS

These studies suggest that the Hebb effect is essentially preserved within Down syndrome, implying that explicit verbal short-term memory is dissociable from potentially more implicit Hebb learning. The relative strength in receptive vocabulary observed in Down syndrome may therefore be supported by largely intact long-term as opposed to short-term serial order learning. This in turn may have implications for teaching methods and interventions that present new phonological material to individuals with Down syndrome.

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.

Das verbale Kurzzeitgedächtnis als Produkt der Interaktion zwischen Aufmerksamkeitskapazitäten, Sequenzverarbeitung und Aktivierung des Sprachsystems

Zusammenfassung. In diesem Beitrag wird ein theoretisches Modell diskutiert, das das verbale Arbeitsgedächtnis als einen Systemverbund auffasst, in dem Aufmerksamkeitskapazitäten, das Sprachsystem und ein Sequenzverarbeitungssystem miteinander verbunden sind. Ausgangspunkt der Überlegungen ist der bekannte Zusammenhang zwischen Kurzzeitgedächtnis und lexikalischer Sprachentwicklung. Mittels Studien aus der Entwicklungspsychologie, der experimentellen Psychologie und der kognitiven Neurowissenschaften wird gezeigt, dass ein großer Teil der Prozesse, die mit Kurzzeitgedächtnistests gemessen werden, durch Aufmerksamkeitskapazitäten und eine Aktivierung des Sprachsystems erklärt werden können. Eine mögliche Ausnahme ist die Verarbeitung zeitlicher Abfolgeinformation. Dies könnte eine spezifische Funktion eines Kurzzeitgedächtnissystems darstellen, die ausschlaggebend ist für das Erlernen verbaler Sequenzen und neuer Wortformen.

Supercalifragilisticexpialidocious: how the brain learns words never heard before

Vocabulary acquisition is such a major aspect of language learning in children, but also in adults when learning a foreign language, that a dedicated vocabulary learning device may exist within the language organ. To identify the relevant brain systems, we performed regional cerebral blood flow measurements in normal subjects while they were learning a list of neologisms or a list of word-nonword pairs. Structures implicated in phonological short-term memory (Broca's area, left temporo-parietal junction) were steadily activated during nonwords learning, while the left temporal lobe neocortical and paralimbic structures (parahippocampal region), associated with long-term memory, contributed to learning in a time-dependent manner, with maximal activation at the beginning of the process. The neural system specifically activated when learning new vocabulary was strongly lateralized to the left hemisphere. This evidence refines current models of memory function and supports theories which emphasise the importance of phonological competence in hemispheric dominance for language.

Are working memory measures free of socioeconomic influence?

PURPOSE

This study evaluated the impact of socioeconomic factors on children's performance on tests of working memory and vocabulary.

METHOD

Twenty Brazilian children, aged 6 and 7 years, from low-income families, completed tests of working memory (verbal short-term memory and verbal complex span) and vocabulary (expressive and receptive). A further group of Brazilian children from families of higher socioeconomic status matched for age, gender, and nonverbal ability also participated in the study.

RESULTS

Children from the low socioeconomic group obtained significantly lower scores on measures of expressive and receptive vocabulary than their higher income peers but no significant group differences were found on the working memory measures.

CONCLUSION

Measures of working memory provide assessments of cognitive abilities that appear to be impervious to substantial differences in socioeconomic background. As these measures are highly sensitive to language ability and learning in general, they appear to provide useful methods for diagnosing specific learning difficulties that are independent of environmental opportunity.

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.

Phonological similarity and lexicality effects in children's verbal short-term memory: concerns about the interpretation of probed recall data

Probed recall tasks are often used to assess aspects of children's verbal short-term memory development because they are not subject to potentially confounding output effects. However, the marked recency effects that are observed in probed recall means that these tasks are potentially insensitive to experimental manipulations when later serial positions are probed. This clouds the interpretation of data from probed recall studies in which children of different ages are presented with to-be-remembered lists of different lengths. In two experiments we examined the magnitude of phonological similarity and lexicality effects in both 5- to 6- and 8- to 9-year-old children. In each case performance on probed recall tasks was contrasted with that seen on tests of serial recognition. The results indicated that probed recall tasks are potentially less sensitive to experimental manipulations in younger than older children. However, comparable effects of both phonological similarity and lexicality were seen in both age groups using serial recognition procedures. These findings have implications for the interpretation of other studies that have examined the development of verbal short-term memory using probed recall and for theoretical accounts of the development of phonological similarity and lexicality effects in children.

Contribution of implicit sequence learning to spoken language processing: some preliminary findings with hearing adults

Spoken language consists of a complex, sequentially arrayed signal that contains patterns that can be described in terms of statistical relations among language units. Previous research has suggested that a domain-general ability to learn structured sequential patterns may underlie language acquisition. To test this prediction, we examined the extent to which implicit sequence learning of probabilistically structured patterns in hearing adults is correlated with a spoken sentence perception task under degraded listening conditions. Performance on the sentence perception task was found to be correlated with implicit sequence learning, but only when the sequences were composed of stimuli that were easy to encode verbally. Implicit learning of phonological sequences thus appears to underlie spoken language processing and may indicate a hitherto unexplored cognitive factor that may account for the enormous variability in language outcomes in deaf children with cochlear implants. The present findings highlight the importance of investigating individual differences in specific cognitive abilities as a way to understand and explain language in deaf learners and, in particular, variability in language outcomes following cochlear implantation.

Short-term memory and the left intraparietal sulcus: focus of attention? Further evidence from a face short-term memory paradigm

This study explored the validity of an attentional account for the involvement of the left intraparietal sulcus (IPS) in visual STM tasks. This account considers that during STM tasks, the IPS acts as an attentional modulator, maintaining activation in long-term memory networks that underlie the initial perception and processing of the specific information to be retained. In a recognition STM paradigm, we presented sequences of unfamiliar faces and instructed the participants to remember different types of information: either the identity of the faces or their order of presentation. We hypothesized that, if the left IPS acts as an attentional modulator, it should be active in both conditions, but connected to different neural networks specialized in serial order or face identity processing. Our results showed that the left IPS was activated during both order and identity encoding conditions, but for different reasons. During order encoding, the left IPS showed functional connectivity with order processing areas in the right IPS, bilateral premotor and cerebellar cortices, reproducing earlier results obtained in a verbal STM experiment. During identity encoding, the left IPS showed preferential functional connectivity with right temporal, inferior parietal and medial frontal areas involved in detailed face processing. These results not only support an attentional account of left IPS involvement in visual STM, but given their similarity with previous results obtained for a verbal STM task, they further highlight the importance of the left IPS as an attentional modulator in a variety of STM tasks.

The left intraparietal sulcus and verbal short-term memory: focus of attention or serial order?

One of the most consistently activated regions during verbal short-term memory (STM) tasks is the left intraparietal sulcus (IPS). However, its precise role remains a matter of debate. While some authors consider the IPS to be a specific store for serial order information, other data suggest that it serves a more general function of attentional focalization. In the current fMRI experiment, we investigated these two hypotheses by presenting different verbal STM conditions that probed recognition for word identity or word order and by assessing functional connectivity of the left IPS with distant brain areas. If the IPS has a role of attentional focalization, then it should be involved in both order and item conditions, but it should be connected to different brain regions, depending on the neural substrates involved in processing the different types of information (order versus phonological/orthographic) to be remembered in the item and order STM conditions. We observed that the left IPS was activated in both order and item STM conditions but for different reasons: during order STM, the left IPS was functionally connected to serial/temporal order processing areas in the right IPS, premotor and cerebellar cortices, while during item STM, the left IPS was connected to phonological and orthographic processing areas in the superior temporal and fusiform gyri. Our data support a position considering that the left IPS acts as an attentional modulator of distant neural networks which themselves are specialized in processing order or language representations. More generally, they strengthen attention-based accounts of verbal STM.