Verbal Short-term Memory Capacity Research Articles

The 10-Word Auditory Verbal Learning Test and Vocabulary Performance in 4- and 5-Year-Old Children.

Understanding the different factors that determine vocabulary development in young children is essential for the diagnosis and rehabilitation of language disorders in children. Language development is closely related to other cognitive processes such as auditory verbal learning and memory. This research focuses on the development of a novel auditory verbal learning test (AVLT) for 4- and 5-year-old children within the Dutch population. This new test is an adaptation of the common AVLT for both older children and adults, usually including a list of 15 words. Considering the lower attention span and limited executive functioning in young children, the word list of this new instrument is reduced to 10 words. Besides, a second recognition form has been developed to improve the ability to distinguish between possible underlying learning and memory deficits. Ninety-five preschool children (ages 4;0-5;12 [years;months]) were tested with this new AVLT 10-word test for kids (10WT-K), yielding different measures of verbal auditory memory. Forty-eight of 95 children received a recognition task with semantically unrelated items, and 47 of 95 received a recognition task with semantically related items. Three additional language skills were assessed to establish test validation: receptive and expressive vocabulary performance and nonword repetition. Outcome of the 10WT-K was related to scores on the language measures. Positive correlations were found between the total score of the 10WT-K and all three aforementioned language skills. We found no correlations between frequency of error types (intrusions and repetitions) and language measures. Furthermore, children who were administered the recognition list with semantically related items showed fewer correct answers and more false-positive and false-negative responses than children who received a recognition list with semantically unrelated items. The 10WT-K for young children can be used to (a) measure different aspects of auditory verbal learning and memory, (b) clarify the nature of possible verbal learning difficulties, and (c) identify a possible nature of language disorders. The word recognition task tested with semantically related items provides a more accurate measurement of individual differences, namely, in distinguishing retrieval and storage abilities. The significant relation found between auditory verbal short-term memory capacity and vocabulary performance in preschool children is a first step toward establishing test validity.

Is short-term memory capacity (7±2) really predicted by theta to gamma cycle length ratio?

Several studies suggest that EEG parameters, reflecting top-down processes in the brain, may predict cognitive performance, e.g. short-term memory (STM) capacity. According to Lisman and Idiart’s model, STM capacity is predicted by theta and gamma EEG waves and their ratio. This model suggests that the more periods of gamma band waves fit into one period of theta band waves, the more information can be stored. We replicated the study by Kaminski et al. (2011), which recorded spontaneous EEG activity and measured verbal STM capacity with a modified digit span task from the Wechsler battery. Our study included more subjects and two EEG recording sessions. We discuss the possible limits of EEG correlates of STM capacity as EEG parameters were not stable across the two measurements and no correlation was found between the theta/gamma ratio and performance in the digit span task.

Chunking and data compression in verbal short-term memory

Short-term verbal memory is improved when words can be chunked into larger units. Miller (1956) suggested that the capacity of verbal short-term memory is determined by the number of chunks that can be stored in memory, rather than by the number of items or the amount of information. But how does the improvement due to chunking come about, and is memory really determined by the number of chunks? One possibility is that chunking is a form of data compression. It allows more information to be stored in the available capacity. An alternative is that chunking operates primarily by redintegration. Chunks exist only in long-term memory, and enable the corresponding items in short-term memory to be reconstructed more reliably from a degraded trace. We review the data favoring each of these views and discuss the implications of treating chunking as data compression. Contrary to Miller, we suggest that memory capacity is primarily determined both by the amount of information that can be stored but also by the underlying representational vocabulary of the memory system. Given the limitations on the representations that can be stored in verbal short-term memory, chunking can sometimes allow the information capacity of short-term memory to be exploited more efficiently. (202 words).

Correlations between Syntactic Development and Verbal Memory in the Spoken Language of Children with Autism Spectrum Disorders and Down Syndrome: Comparison with Typically Developing Children

Correlations between syntactic development and verbal memory of children with intellectual disabilities (ID) are not well understood. These correlations were investigated in children with Autism Spectrum Disorders (ASD) with intellectual disabilities and children with Down Syndrome (DS). Thirty-seven children with ID (11 with ASD, 16 with DS, and 10 with ID not falling under ASD or DS) and a control group of typically developing (TD) children (N = 58) participated. Their verbal short-term memory was assessed using the digit span tasks. Verbal long-term memory was assessed using Rey’s Auditory Verbal Learning Test (AVLT) and syntactic understanding and expression tasks. Syntactic understanding and expression scores of the disability groups were significantly lower than TD children of the same mental age (MA). AVLT’s immediate recall scores were significantly lower in children with ASD, whereas, in children with DS, the digit span forward scores and immediate and delayed recall AVLT scores were significantly lower than in TD children of the same MA. Verbal short-term memory assessed by AVLT in children with ASD and the small capacity of verbal short-term memory in children with DS are correlated with syntactic development.

Cross-situational word learning in aphasia

Human learners can resolve referential ambiguity and discover the relationships between words and meanings through a cross-situational learning (CSL) strategy. Some people with aphasia (PWA) can learn word-referent pairings under referential uncertainty supported by online feedback. However, it remains unknown whether PWA can learn new words cross-situationally and if such learning ability is supported by statistical learning (SL) mechanisms. The present study examined whether PWA can learn novel word-referent mappings in a CSL task without feedback. We also studied whether CSL is related to SL in PWA and neurologically healthy individuals. We further examined whether aphasia severity, phonological processing and verbal short-term memory (STM) predict CSL in aphasia, and also whether individual differences in verbal STM modulate CSL in healthy older adults. Sixteen people with chronic aphasia underwent a CSL task that involved exposure to a series of individually ambiguous learning trials and a SL task that taps speech segmentation. Their learning ability was compared to 18 older controls and 39 young adults recruited for task validation. CSL in the aphasia group was below the older controls and young adults and took place at a slower rate. Importantly, we found a strong association between SL and CSL performance in all three groups. CSL was modulated by aphasia severity in the aphasia group, and by verbal STM capacity in the older controls. Our findings indicate that some PWA can preserve the ability to learn new word-referent associations cross-situationally. We suggest that both PWA and neurologically intact individuals may rely on SL mechanisms to achieve CSL and that verbal STM also influences CSL. These findings contribute to the ongoing debate on the cognitive mechanisms underlying this learning ability.

Novel word acquisition in aphasia: Facing the word-referent ambiguity of natural language learning contexts

Recent research suggests that some people with aphasia preserve some ability to learn novel words and to retain them in the long-term. However, this novel word learning ability has been studied only in the context of single word-picture pairings. We examined the ability of people with chronic aphasia to learn novel words using a paradigm that presents new word forms together with a limited set of different possible visual referents and requires the identification of the correct word-object associations on the basis of online feedback. We also studied the relationship between word learning ability and aphasia severity, word processing abilities, and verbal short-term memory (STM). We further examined the influence of gross lesion location on new word learning. The word learning task was first validated with a group of forty-five young adults. Fourteen participants with chronic aphasia were administered the task and underwent tests of immediate and long-term recognition memory at 1 week. Their performance was compared to that of a group of fourteen matched controls using growth curve analysis. The learning curve and recognition performance of the aphasia group was significantly below the matched control group, although above-chance recognition performance and case-by-case analyses indicated that some participants with aphasia had learned the correct word-referent mappings. Verbal STM but not word processing abilities predicted word learning ability after controlling for aphasia severity. Importantly, participants with lesions in the left frontal cortex performed significantly worse than participants with lesions that spared the left frontal region both during word learning and on the recognition tests. Our findings indicate that some people with aphasia can preserve the ability to learn a small novel lexicon in an ambiguous word-referent context. This learning and recognition memory ability was associated with verbal STM capacity, aphasia severity and the integrity of the left inferior frontal region.

Effects of working memory load on processing of sounds and meanings of words in aphasia

Background: Language performance in aphasia can vary depending on several variables such as stimulus characteristics and task demands. This study focuses on the degree of verbal working memory (WM) load inherent in the language task and how this variable affects language performance by individuals with aphasia. Aims: The first aim was to identify the effects of increased verbal WM load on the performance of judgements of semantic similarity (synonymy) and phonological similarity (rhyming). The second aim was to determine if any of the following abilities could modulate the verbal WM load effect: semantic or phonological access, semantic or phonological short-term memory (STM), and any of the following executive processing abilities: inhibition, verbal WM updating, and set shifting. Method & Procedures: A total of 31 individuals with aphasia and 11 controls participated in this study. They were administered a synonymy judgement task and a rhyming judgement task under high and low verbal WM load conditions that were compared to each other. In a second set of analyses multiple regression was used to identify which factors (as noted above) modulated the verbal WM load effect. Outcomes & Results: For participants with aphasia, increased verbal WM load significantly reduced accuracy of performance on synonymy and rhyming judgements. Better performance in the low verbal WM load conditions was evident even after correcting for chance. The synonymy task included concrete and abstract word triplets. When these were examined separately the verbal WM load effect was significant for the abstract words, but not the concrete words. The same pattern was observed in the performance of the control participants. Additionally, the second set of analyses revealed that semantic STM and one executive function, inhibition ability, emerged as the strongest predictors of the verbal WM load effect in these judgement tasks for individuals with aphasia. Conclusions: The results of this study have important implications for diagnosis and treatment of aphasia. As the roles of verbal STM capacity, executive functions and verbal WM load in language processing are better understood, measurements of these variables can be incorporated into our diagnostic protocols. Moreover, if cognitive abilities such as STM and executive functions support language processing and their impairment adversely affects language function, treating them directly in the context of language tasks should translate into improved language function.

Short-term verbal memory and psychophysiological response to emotion-related words in children who stutter

Emotions play a significant role in fluency disorders. In this research we wanted to examine immediate and delayed verbal recall for auditory presented words that carry information about different emotional state (emotion-related words) and emotionally neutral words in children who stutter (N=35) and their peers (N=35). Using only word semantics, we wanted to eliminate emotional verbal expression of words as a factor that can influence memory abilities. In addition, we also wanted to examine skin conductance measure as an indicator of autonomic nervous system arousal during short-term memory task for emotion-related and emotionally neutral words. Parental questionnaire (Stuttering Intensity in Children Who Stutter in Positive and Negative Emotion-Related Everyday Situations) was given to parents of children who stutter in order to collect data regarding stuttering severity in emotionally arousing situations in everyday life. Differences between the experimental and the control group in global memory capacity are highest in immediate recall (p=0,01) with the tendency for lowering statistical significance with prolongation of retention interval. According to the questionnaire results, children who stutter show a higher degree of stuttering in situations with positive emotional valence (p< 0.00). Skin conductance measurements showed higher autonomic nervous system arousal during perception and free recall of positive emotion-related words in children who stutter when compared to negative and emotionally neutral words. The results indicate higher emotional arousal to positive emotions in children who stutter (p=0.02), leading to either less fluent speech or suppression of verbal short-term memory capacity.

Evidence for Preserved Novel Word Learning in Down Syndrome Suggests Multiple Routes to Vocabulary Acquisition

Three studies investigated novel word learning, some requiring phonological production, each involving between 11 and 17 individuals with Down syndrome, and between 15 and 24 typically developing individuals matched for receptive vocabulary. The effect of stimuli wordlikeness and incidental procedure-based memory demands were examined to see whether these may account for an apparent impairment in word learning in Down syndrome demonstrated in earlier research. Paired associate word and nonword learning tasks were presented, requiring participants to learn the names of novel characters. The nonword stimuli varied in the degree of wordlikeness in 2 studies. A third study investigated extraneous task demand. Across 3 studies, there was no suggestion of a word learning deficit associated with Down syndrome (η(2)(p) for the main effect of group of .03, .11, and .03, respectively), despite the level of phonological representation required. There was evidence that novel word learning by participants with Down syndrome exceeded that which their verbal short-term memory capacity would predict. Vocabulary acquisition in Down syndrome may not rely on verbal short-term memory to the same extent as in typically developing children, lending support to the suggestion that new word learning may be underpinned by an additional memory process.

Short-term memory capacity (7 ± 2) predicted by theta to gamma cycle length ratio

The number of items that can be held in human short-term memory (STM) is limited to 7 (±2) elements. Lisman and Idiart’s theoretical model of STM proposes that this value depends on the number of gamma cycles that can fit in one theta cycle. Previous studies on animals and humans provided support for this hypothesis but direct evidence from human EEG scalp recordings has not previously been reported. We recorded spontaneous EEG activity from 17 participants and measured their verbal STM capacity with a modified digit span task from the Wechsler battery. The strong and positive correlation we found between verbal STM capacity and theta/gamma cycle length ratio thus provides a direct argument in favor of this STM theoretical model. In this study we also demonstrated a new method for assessing individual theta and gamma frequencies by detecting functional coupling between these oscillations.

Short- and long-term memory contributions to immediate serial recognition: Evidence from serial position effects

A long-standing body of research supports the existence of separable short- and long-term memory systems, relying on phonological and semantic codes, respectively. The aim of the current study was to measure the contribution of long-term knowledge to short-term memory performance by looking for evidence of phonologically and semantically coded storage within a short-term recognition task, among developmental samples. Each experimental trial presented 4-item lists. In Experiment 1 typically developing children aged 5 to 6 years old showed evidence of phonologically coded storage across all 4 serial positions, but evidence of semantically coded storage at Serial Positions 1 and 2. In a further experiment, a group of individuals with Down syndrome was investigated as a test case that might be expected to use semantic coding to support short-term storage, but these participants showed no evidence of semantically coded storage and evidenced phonologically coded storage only at Serial Position 4, suggesting that individuals with Down syndrome have a verbal short-term memory capacity of 1 item. Our results suggest that previous evidence of semantic effects on "short-term memory performance" does not reflect semantic coding in short-term memory itself, and provide an experimental method for researchers wishing to take a relatively pure measure of verbal short-term memory capacity, in cases where rehearsal is unlikely.

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.

Reduced short-term memory capacity in Alzheimer's disease: The role of phonological, lexical, and semantic processing

Individuals with Alzheimer's disease (AD) are often reported to have reduced verbal short-term memory capacity, typically attributed to their attention/executive deficits. However, these individuals also tend to show progressive impairment of semantic, lexical, and phonological processing which may underlie their low short-term memory capacity. The goals of this study were to assess the contribution of each level of representation (phonological, lexical, and semantic) to immediate serial recall performance in 18 individuals with AD, and to examine how these linguistic effects on short-term memory were modulated by their reduced capacity to manipulate information in short-term memory associated with executive dysfunction. Results showed that individuals with AD had difficulty recalling items that relied on phonological representations, which led to increased lexicality effects relative to the control group. This finding suggests that patients have a greater reliance on lexical/semantic information than controls, possibly to make up for deficits in retention and processing of phonological material. This lexical/semantic effect was not found to be significantly correlated with patients’ capacity to manipulate verbal material in short-term memory, indicating that language processing and executive deficits may independently contribute to reducing verbal short-term memory capacity in AD.

Working memory demands in insight versus analytic problem solving

Working memory is one of the cognitive processes thought to differentiate insight and analytic forms of problem solving. The present research examined memory involvement in the solution of insight versus analytic problems. Participants completed verbal and spatial working memory and short-term memory measures and a series of analytic and insight problems. Results demonstrated a relationship between working-memory capacity and the solution of analytic problems and between verbal short-term memory capacity and the solution of insight problems. This distinction was generally though not universally supported when memory was examined in relation to individual problems. Memory involvement in insight problem solving was further examined to clarify whether restructuring in insight is the end result of active memory search or spontaneous processes. The present research supports the theory that differences exist in the cognitive processes underlying insight versus analytic problem solving, and provides support for the spontaneous theory of restructuring in insight.

Effect of Perceiving Computing to Be an Acquirable Skill upon a Computer-Mediated Serial Recall Task

Serial recall tasks assess the capacity of verbal short-term memory. The perception of computing as an acquirable skill rather than a fixed ability affected performance upon computer-based serial recall tasks but did not affect performance on comparable pencil-and-paper tasks. Computerized versions of traditional assessments should control for this.

Verbal Short-Term Memory Span in Speech-Disordered Children: Implications for Articulatory Coding in Short-Term Memory

One influential explanation of the development of verbal short-term memory in children argues that short-term memory capacity is a direct function of speech rate. This theory predicts that children with pathologically slow speech will show reduced verbal short-term memory capacity and will show less evidence of speech-base coding on verbal memory tasks. To test this prediction, verbal short-term memory span was assessed using a task that did not require a verbal response in 37 speech-disordered children and 37 age- and sex-matched controls (age range 4-15 years). The speech-disordered group had a significantly lower short-term memory capacity, a smaller word length effect, and reduced speech-motor activity during rehearsal periods. Covariance analyses revealed that these differences were not a function of general intellectual or motor speed differences between the groups, and that speech rate as a covariate abolished group differences in short-term memory. These results suggest that speech rate may be a causal determinant of verbal short-term memory capacity.