Word-frequency and phonological-neighborhood effects on verbal short-term memory

The Cerebellum Is Sensitive to the Lexical Properties of Words During Spoken Language Comprehension

Over the past few decades, research into the function of the cerebellum has expanded far beyond the motor domain. A growing number of studies are probing the role of specific cerebellar subregions, such as Crus I and Crus II, in higher-order cognitive functions including receptive language processing. In the current fMRI study, we show evidence for the cerebellum's sensitivity to variation in two well-studied psycholinguistic properties of words-lexical frequency and phonological neighborhood density-during passive, continuous listening of a podcast. To determine whether, and how, activity in the cerebellum correlates with these lexical properties, we modeled each word separately using an amplitude-modulated regressor, time-locked to the onset of each word. At the group level, significant effects of both lexical properties landed in expected cerebellar subregions: Crus I and Crus II. The BOLD signal correlated with variation in each lexical property, consistent with both language-specific and domain-general mechanisms. Activation patterns at the individual level also showed that effects of phonological neighborhood and lexical frequency landed in Crus I and Crus II as the most probable sites, though there was activation seen in other lobules (especially for frequency). Although the exact cerebellar mechanisms used during speech and language processing are not yet evident, these findings highlight the cerebellum's role in word-level processing during continuous listening.

Reduced benefit from long-term item frequency contributes to short-term memory deficits in dyslexia

Dyslexia, a specific difficulty in acquiring proficient reading, is also characterized by reduced short-term memory (STM) capacity. Extensive research indicates that individuals with developmental dyslexia (IDDs) benefit less from exposure, and this hampers their long-term knowledge accumulation. It is well established that long-term knowledge has a great effect on performance in STM tasks, and thus IDDs' reduced benefit of exposure could potentially reduce their relative performance in such tasks, especially when frequent items, such as digit-words, are used. In this study we used a standard, widely used, STM assessment: the Digit Span subtest from the Wechsler Adult Intelligence Scale. The task was conducted twice: in native language and in second language. As exposure to native language is greater than exposure to second language, we predicted that IDDs' performance in the task administered in native language will reveal a larger group difference as compared to second language, due to IDDs' reduced benefit of item frequency. The prediction was confirmed, in line with the hypothesis that reduced STM in dyslexia to a large extent reflects reduced benefits from long-term item frequency and not a reduced STM per se.

Effects of lexical skills and orthographic neighborhood size in word memory

Two experiments were designed to investigate the relationship between individual lexical skills in young adults and memory performance on words varying by their orthographic neighborhood size. In Experiment 1, a sample of 100 university students were administrated a set of spelling, reading, and vocabulary tests to assess their lexical skills. Then, they had to learn mixed lists of words from high and low neighborhood size and perform free recall and memory recognition tasks. Importantly, high lexical skills were found to enhance free recall and, to a lesser extent, recognition. In addition, a typical mirror effect of neighborhood size was found in recognition as words were better recognized and also produced less false alarms when they had a low neighborhood size. In Experiment 2, pure lists of words were designed and a new sample of 90 university students was assessed. We replicated the effect of lexical skills in free recall and the effect of neighborhood size for hits in recognition. Spelling skills were found to interact with neighborhood size in free recall in that low spelling skills were associated with a facilitatory effect of neighborhood size. In recognition, a relation between reading skills and neighborhood size was found such that the higher the reading skills, the higher was the inhibitory effect of neighborhood size. These results provide new evidence of an influence of lexical skills in word memory performance and underline the role of orthographic neighborhood size in episodic memory tasks.

Identifying Links Between Latent Memory and Speech Recognition Factors

OBJECTIVES

The link between memory ability and speech recognition accuracy is often examined by correlating summary measures of performance across various tasks, but interpretation of such correlations critically depends on assumptions about how these measures map onto underlying factors of interest. The present work presents an alternative approach, wherein latent factor models are fit to trial-level data from multiple tasks to directly test hypotheses about the underlying structure of memory and the extent to which latent memory factors are associated with individual differences in speech recognition accuracy. Latent factor models with different numbers of factors were fit to the data and compared to one another to select the structures which best explained vocoded sentence recognition in a two-talker masker across a range of target-to-masker ratios, performance on three memory tasks, and the link between sentence recognition and memory.

DESIGN

Young adults with normal hearing (N = 52 for the memory tasks, of which 21 participants also completed the sentence recognition task) completed three memory tasks and one sentence recognition task: reading span, auditory digit span, visual free recall of words, and recognition of 16-channel vocoded Perceptually Robust English Sentence Test Open-set sentences in the presence of a two-talker masker at target-to-masker ratios between +10 and 0 dB. Correlations between summary measures of memory task performance and sentence recognition accuracy were calculated for comparison to prior work, and latent factor models were fit to trial-level data and compared against one another to identify the number of latent factors which best explains the data. Models with one or two latent factors were fit to the sentence recognition data and models with one, two, or three latent factors were fit to the memory task data. Based on findings with these models, full models that linked one speech factor to one, two, or three memory factors were fit to the full data set. Models were compared via Expected Log pointwise Predictive Density and post hoc inspection of model parameters.

RESULTS

Summary measures were positively correlated across memory tasks and sentence recognition. Latent factor models revealed that sentence recognition accuracy was best explained by a single factor that varied across participants. Memory task performance was best explained by two latent factors, of which one was generally associated with performance on all three tasks and the other was specific to digit span recall accuracy at lists of six digits or more. When these models were combined, the general memory factor was closely related to the sentence recognition factor, whereas the factor specific to digit span had no apparent association with sentence recognition.

CONCLUSIONS

Comparison of latent factor models enables testing hypotheses about the underlying structure linking cognition and speech recognition. This approach showed that multiple memory tasks assess a common latent factor that is related to individual differences in sentence recognition, although performance on some tasks was associated with multiple factors. Thus, while these tasks provide some convergent assessment of common latent factors, caution is needed when interpreting what they tell us about speech recognition.

The orthographic/phonological neighbourhood size effect and set size

A growing number of studies have shown that on serial recall tests, words with more orthographic/phonological neighbours are better recalled than otherwise comparable words with fewer neighbours, the so-called neighbourhood size effect. Greeno et al. replicated this result when using a large stimulus pool but found a reverse neighbourhood size effect-better recall of words with fewer rather than more neighbours-when using a small stimulus pool. We report three registered experiments that further examine the role of set size in the neighbourhood size effect. Experiment 1 used the large pool from Greeno et al. and replicated their finding of a large-neighbourhood advantage. Experiment 2 used the small pool from Greeno et al. but found no difference in recall between the large and small neighbourhood conditions. Experiment 3 also used a small pool but the small pool was randomly generated for each subject from the large pool used in Experiment 1. This resulted in a typical large neighbourhood advantage. We suggest that set size is not critical to the direction of the neighbourhood size effect, with a large neighbourhood advantage appearing with both small and large pools.

A web-based interface to calculate phonological neighborhood density for words and nonwords in Modern Standard Arabic

The availability of online databases (e.g., Balota et al., 2007) and calculators (e.g., Storkel & Hoover, 2010) has contributed to an increase in psycholinguistic-related research, to the development of evidence-based treatments in clinical settings, and to scientifically supported training programs in the language classroom. The benefit of online language resources is limited by the fact that the majority of such resources provide information only for the English language (Vitevitch, Chan & Goldstein, 2014). To address the lack of diversity in these resources for languages that differ phonologically and morphologically from English, the present article describes an online database to compute phonological neighborhood density (i.e., the number of words that sound similar to a given word) for words and nonwords in Modern Standard Arabic (MSA). A full description of how the calculator can be used is provided. It can be freely accessed at https://calculator.ku.edu/density/about .

Repeated series learning revisited with a novel prediction on the reduced effect of item frequency in dyslexia

Developmental dyslexia, a difficulty with acquiring fluent reading, has also been characterized by reduced short-term memory (STM) capacity, which is often operationalized with span tasks. The low performance of individuals with dyslexia (IDDs) in such tasks is commonly attributed to poor phonological memory. However, we suggest an alternative explanation based on the observation that many times the items that are used in spans tasks are high-frequency items (e.g., digit words). We suggest that IDDs do not enjoy the benefit of item frequency to the same extent as controls, and thus their performance in span tasks is especially hampered. On the contrary, learning of repeated sequences was shown to be largely independent of item frequency, and therefore this type of learning may be unimpaired in dyslexia. To test both predictions, we used the Hebb-learning paradigm. We found that IDDs’ performance is especially poor compared to controls’ when high-frequency items are used, and that their repeated series learning does not differ from that of controls. Taken together with existing literature, our findings suggest that impaired learning of repeated series is not a core characteristic of dyslexia, and that the reports on reduced STM in dyslexia may to a large extent be explained by reduced benefit of item frequency.

Integrity of input verbal short-term memory ability predicts naming accuracy in aphasia

Background

Contemporary models of aphasia predominantly attribute lexical retrieval deficits to impaired access and/or maintenance of semantic, lexical, and phonological representations of words. A central hypothesis of language-emergent models of verbal short-term memory (STM) is that temporary storage and maintenance of verbal information arises from activation of linguistic representations in long-term memory. This close relationship between short-term retention and linguistic representations has prompted accounts of aphasia that include impairments to both these components.

Aims

We investigated associations between measures of input semantic and phonological verbal STM and corresponding output processing measures. We hypothesised that both input and output functions of verbal STM rely on a common substrate (i.e., temporary activation and maintenance of long-term linguistic representations).

Methods & Procedure

Twenty adults with aphasia completed a series of semantic and phonological probe spans. Results were compared with naming performance in immediate and delayed conditions. The data were analysed using correlations, principal components analysis and linear regressions.

Results & Discussion

Input semantic and phonological verbal STM abilities were predictive of naming accuracy. Greater input semantic and phonological STM spans were associated with fewer semantic and phonological naming errors. Latent factors identified by principal components analysis of probe span data were consistent with a two-step interactive model of word retrieval. Probe spans measuring access to semantic and initial consonant-vowel representations aligned with lexical-semantic abilities (lexical-semantic factor). Probe spans assessing access to the rhyme component of a word measured lexical-phonological abilities (lexical-phonological factor). The principal components analysis indicated that stronger lexical-semantic abilities were associated with fewer semantic and nonword errors, and stronger lexical phonological abilities were associated with fewer formal and unrelated errors. In addition, our results were consistent with models that postulate serial access to phonology, proceeding from initial to final phonemes. The span measuring access to initial consonant-vowel was associated with lexical selection, while the span measuring access to rhyme information was associated with phonological selection.

Conclusion

Performance on input semantic and phonological tasks predicts accuracy of picture naming performance and types of errors made by people with aphasia. These results indicate overlap in input and output semantic and phonological processing, which must be accounted for in models of lexical processing. These findings also have implications for approaches to diagnosis and treatments for lexical comprehension and production that capitalise on the overlap of input and output processing.

EXPRESS: The Company a Word Keeps: The Role of Neighbourhood Density in Verbal Short-Term Memory

Psycholinguistic information plays an important role in verbal memory over the short-term (vSTM). One such linguistic feature is neighbourhood density (ND)-the number of words that can be derived from a given word by changing a single phoneme or single letter-so that vSTM performance is better when word sequences are from dense rather than sparse neighbourhoods, an effect attributed to higher levels of supportive activation among neighbouring words. Generally, it has been assumed that lexical variables influence item memory but not order memory, and we show that the typical vSTM advantage for dense neighbourhood words in serial recall is eliminated when using serial recognition. However, we also show that the usual effect of ND is reversed-for both serial recall and serial recognition-when using a subset of those same words. The findings call into question the way in which ND has been incorporated into accounts of vSTM that invoke mutual support from long-term representations on either encoding or retrieval.

Can activated long-term memory maintain serial order information?

The maintenance of serial order information is a core component of working memory (WM). Many theoretical models assume the existence of specific serial order mechanisms. Those are considered to be independent from the linguistic system supporting maintenance of item information. This is based on studies showing that psycholinguistic factors strongly affect the ability to maintain item information, while leaving order recall relatively unaffected. Recent language-based accounts suggest, however, that the linguistic system could provide mechanisms that are sufficient for serial order maintenance. A strong version of these accounts postulates serial order maintenance as emerging from the pattern of activation occurring in the linguistic system. In the present study, we tested this assumption via a computational modeling approach by implementing a purely activation-based architecture. We tested this architecture against several experiments involving the manipulation of semantic relatedness, a psycholinguistic variable that has been shown to interact with serial order processing in a complex manner. We show that this activation-based architecture struggles to account for interactions between semantic knowledge and serial order processing. This study fails to support activated long-term memory as an exclusive mechanism supporting serial order maintenance.

Accessibility and Historical Change: An Emergent Cluster Led Uncles and Aunts to Become Aunts and Uncles

There are times when a curiously odd relic of language presents us with a thread, which when pulled, reveals deep and general facts about human language. This paper unspools such a case. Prior to 1930, English speakers uniformly preferred male-before-female word order in conjoined nouns such as uncles and aunts; nephews and nieces; men and women. Since then, at least a half dozen items have systematically reversed their preferred order (e.g., aunts and uncles, nieces and nephews) while others have not (men and women). We review evidence that the unusual reversals began with mother and dad(dy) and spread to semantically and morphologically related binomials over a period of decades. The present work proposes that three aspects of cognitive accessibility combine to quantify the probability of A&B order: (1) the relative accessibility of the A&B terms individually, (2) competition from B&A order, and critically, (3) cluster strength (i.e., similarity to related A'&B' cases). The emergent cluster of female-first binomials highlights the influence of semantic neighborhoods in memory retrieval. We suggest that cognitive accessibility can be used to predict the word order of both familiar and novel binomials generally, as well as the diachronic change focused on here.

Acoustic-Phonetic Mismatches Impair Serial Recall of Degraded Words

Sequences of phonologically similar words are more difficult to remember than phonologically distinct sequences. This study investigated whether this difficulty arises in the acoustic similarity of auditory stimuli or in the corresponding phonological labels in memory. Participants reconstructed sequences of words which were degraded with a vocoder. We manipulated the phonological similarity of response options across two groups. One group was trained to map stimulus words onto phonologically similar response labels which matched the recorded word; the other group was trained to map words onto a set of plausible responses which were mismatched from the original recordings but were selected to have less phonological overlap. Participants trained on the matched responses were able to learn responses with less training and recall sequences more accurately than participants trained on the mismatched responses, even though the mismatched responses were more phonologically distinct from one another and participants were unaware of the mismatch. The relative difficulty of recalling items in the correct position was the same across both sets of response labels. Mismatched responses impaired recall accuracy across all positions except the final item in each list. These results are consistent with the idea that increased difficulty of mapping acoustic stimuli onto phonological forms impairs serial recall. Increased mapping difficulty could impair retention of memoranda and impede consolidation into phonological forms, which would impair recall in adverse listening conditions.

Short-term memory capacity and sensitivity to language statistics in dyslexia and among musicians

Poor short-term memory (STM) capacity in individuals with dyslexia (IDDs) and enhanced STM capacity in musicians are well documented, yet their causes are disputed. Previous studies also found poor use of stimuli statistics by IDDs and enhanced use by musicians. We hypothesized that these observations are functionally related, as follows: Enhanced sensitivity to statistics facilitates musicians' benefit from each exposure, and reduced sensitivity to statistics hinders IDDs' benefit. Thus, larger group differences are expected for larger exposure: STM capacity, which is sensitive to item familiarity, will thus be larger among musicians, and smaller among IDDS, particularly for high-frequency items. Testing this hypothesis using syllable span, we found that musicians' advantage and IDDs' difficulty were indeed larger for high-frequency syllables than for low-frequency ones. By contrast, benefits from sequence repetition did not differ between musicians, controls and IDDs, suggesting that online sequence learning is based on a different mechanism. To test this dissociation we recruited, in addition to native Hebrew speakers, native English speakers, matched to the Hebrew-speaking controls. Their spans for high-frequency syllables in Hebrew, which do not have high frequency in English, were small - as expected from reduced exposure to these syllables. Yet, their benefit from sequence repetition was similar to that of the three Hebrew-speaking groups. Taken together, these experiments suggest that different sensitivities to item frequency explain some of the population-related variability in STM tasks. By contrast, benefits from sequence repetition do not depend on item familiarity, and do not differ between groups.

Semantic feature effect in verbal short-term memory

The present study explored the influences of semantic features in immediate serial recall in order to further examine the involvement of semantic knowledge in short-term memory. The number of semantic features (NoF) was found to have a positive effect on short-term recall where high NoF words were remembered better than low NoF words (Experiment 1). This effect was replicated in a second experiment and was found to persist even after controlling for a potential confound (number of distinguishing features). It was further found that having more distinctive features facilitated recall performance of words whose representation was semantically poorer (Experiment 3). These results provide additional evidence of semantic influences in short-term memory and demonstrate that the organisation of semantic knowledge is reflected in short-term memory performance.

Interactions Between Item Set and Vocoding in Serial Recall

OBJECTIVES

Serial recall of digits is frequently used to measure short-term memory span in various listening conditions. However, the use of digits may mask the effect of low quality auditory input. Digits have high frequency and are phonologically distinct relative to one another, so they should be easy to identify even with low quality auditory input. In contrast, larger item sets reduce listener ability to strategically constrain their expectations, which should reduce identification accuracy and increase the time and/or cognitive resources needed for identification when auditory quality is low. This diminished accuracy and increased cognitive load should interfere with memory for sequences of items drawn from large sets. The goal of this work was to determine whether this predicted interaction between auditory quality and stimulus set in short-term memory exists, and if so, whether this interaction is associated with processing speed, vocabulary, or attention.

DESIGN

We compared immediate serial recall within young adults with normal hearing across unprocessed and vocoded listening conditions for multiple stimulus sets. Stimulus sets were lists of digits (1 to 9), consonant-vowel-consonant (CVC) words (chosen from a list of 60 words), and CVC nonwords (chosen from a list of 50 nonwords). Stimuli were unprocessed or vocoded with an eight-channel noise vocoder. To support interpretation of responses, words and nonwords were selected to minimize inclusion of multiple phonemes from within a confusion cluster. We also measured receptive vocabulary (Peabody Picture Vocabulary Test [PPVT-4]), sustained attention (test of variables of attention [TOVA]), and repetition speed for individual items from each stimulus set under both listening conditions.

RESULTS

Vocoding stimuli had no impact on serial recall of digits, but reduced memory span for words and nonwords. This reduction in memory span was attributed to an increase in phonological confusions for nonwords. However, memory span for vocoded word lists remained reduced even after accounting for common phonetic confusions, indicating that lexical status played an additional role across listening conditions. Principal components analysis found two components that explained 84% of the variance in memory span across conditions. Component one had similar load across all conditions, indicating that participants had an underlying memory capacity, which was common to all conditions. Component two was loaded by performance in the vocoded word and nonword conditions, representing the sensitivity of memory span to vocoding of these stimuli. The order in which participants completed listening conditions had a small effect on memory span that could not account for the effect of listening condition. Repetition speed was fastest for digits, slower for words, and slowest for nonwords. On average, vocoding slowed repetition speed for all stimuli, but repetition speed was not predictive of individual memory span. Vocabulary and attention showed no correlation with memory span.

CONCLUSIONS

Our results replicated previous findings that low quality auditory input can impair short-term memory, and demonstrated that this impairment is sensitive to stimulus set. Using multiple stimulus sets in degraded listening conditions can isolate memory capacity (in digit span) from impaired item identification (in word and nonword span), which may help characterize the relationship between memory and speech recognition in difficult listening conditions.

Serial Recall Predicts Vocoded Sentence Recognition Across Spectral Resolutions

Purpose The goal of this study was to determine how various aspects of cognition predict speech recognition ability across different levels of speech vocoding within a single group of listeners. Method We tested the ability of young adults (N = 32) with normal hearing to recognize Perceptually Robust English Sentence Test Open-set (PRESTO) sentences that were degraded with a vocoder to produce different levels of spectral resolution (16, eight, and four carrier channels). Participants also completed tests of cognition (fluid intelligence, short-term memory, and attention), which were used as predictors of sentence recognition. Sentence recognition was compared across vocoder conditions, predictors were correlated with individual differences in sentence recognition, and the relationships between predictors were characterized. Results PRESTO sentence recognition performance declined with a decreasing number of vocoder channels, with no evident floor or ceiling performance in any condition. Individual ability to recognize PRESTO sentences was consistent relative to the group across vocoder conditions. Short-term memory, as measured with serial recall, was a moderate predictor of sentence recognition (ρ = 0.65). Serial recall performance was constant across vocoder conditions when measured with a digit span task. Fluid intelligence was marginally correlated with serial recall, but not sentence recognition. Attentional measures had no discernible relationship to sentence recognition and a marginal relationship with serial recall. Conclusions Verbal serial recall is a substantial predictor of vocoded sentence recognition, and this predictive relationship is independent of spectral resolution. In populations that show variable speech recognition outcomes, such as listeners with cochlear implants, it should be possible to account for the independent effects of spectral resolution and verbal serial recall in their speech recognition ability. Supplemental Material https://doi.org/10.23641/asha.12021051.

Verbal Working Memory as Emergent from Language Comprehension and Production

This article reviews current models of verbal working memory and considers the role of language comprehension and long-term memory in the ability to maintain and order verbal information for short periods of time. While all models of verbal working memory posit some interaction with long-term memory, few have considered the character of these long-term representations or how they might affect performance on verbal working memory tasks. Similarly, few models have considered how comprehension processes and production processes might affect performance in verbal working memory tasks. Modern theories of comprehension emphasize that people learn a vast web of correlated information about the language and the world and must activate that information from long-term memory to cope with the demands of language input. To date, there has been little consideration in theories of verbal working memory for how this rich input from comprehension would affect the nature of temporary memory. There has also been relatively little attention to the degree to which language production processes naturally manage serial order of verbal information. The authors argue for an emergent model of verbal working memory supported by a rich, distributed long-term memory for language. On this view, comprehension processes provide encoding in verbal working memory tasks, and production processes maintenance, serial ordering, and recall. Moreover, the computational capacity to maintain and order information varies with language experience. Implications for theories of working memory, comprehension, and production are considered.

Animacy effects extend to working memory: results from serial order recall tasks

Words that represent animate entities (e.g., dog) are recalled from long-term memory more accurately than words representing inanimate entities (e.g., pan). In this research, we examined whether the animacy effect extends to working memory (WM). The potential roles of WM maintenance strategies (rehearsal and directed attention) were also examined. Participants performed serial order recall tasks with sets of 3, 4, 5 or 6 words that were either animate or inanimate. In stage 1 of Experiment 1, participants received no instructions regarding how to maintain the words. In stage 2, participants received either no instructions, sub-vocal rehearsal or directed attention instructions. In all instruction groups and at both stages, significant animacy effects were observed at set sizes of 4, 5 and 6 but not set size 3. The animacy effect was larger at set size 5 than other set sizes. In Experiment 2, participants completed the task with and without articulatory suppression. In both conditions, animacy effects were observed at set sizes 4, 5 and 6, but not at set size 3. The magnitude of the animacy effect declined as set size increased from 4 to 6. Animacy appears to enhance serial recall, but the effect is not dependent on rehearsal.

Linguistische Fairness und differentielle Validität des Auditiven Wortlisten Lerntests (AWLT) bei Demenz vom Alzheimer-Typ

Zusammenfassung. Der Auditive Wortlisten Lerntest (AWLT) ist Teil des Test-Sets Kognitive Funktionen Demenz (CFD; Cognitive Functions Dementia) im Rahmen des Wiener Testsystems (WTS). Der AWLT wurde entlang neurolinguistischer Kriterien entwickelt, um Interaktionen zwischen dem kognitiven Status der Testpersonen und den linguistischen Eigenschaften der Lernliste zu reduzieren. Anhand einer nach Alter, Bildung und Geschlecht parallelisierten Stichprobe von gesunden Probandinnen und Probanden ( N = 44) und Patientinnen und Patienten mit Alzheimer Demenz ( N = 44) wurde mit ANOVAs für Messwiederholungen überprüft, inwieweit dieses Konstruktionsziel erreicht wurde. Weiter wurde die Fähigkeit der Hauptvariablen des AWLT untersucht, zwischen diesen Gruppen zu unterscheiden. Es traten Interaktionen mit geringer Effektstärke zwischen linguistischen Eigenschaften und der Diagnose auf. Die Hauptvariablen trennten mit großen Effektstärken Patientinnen und Patienten von Gesunden. Der AWLT scheint bei vergleichbarer differenzieller Validität linguistisch fairer als ähnliche Instrumente zu sein.

Set size and long-term memory/lexical effects in immediate serial recall: Testing the impurity principle

The impurity principle (Surprenant & Neath, 2009b) states that because memory is fundamentally reconstructive, tasks and processes are not pure. This principle is based on a long line of research showing the effects of one memory system or process on another. Although the principle is widely accepted, many researchers appear hesitant to endorse it in extreme edge cases. One such case involves the effects of long-term memory and lexical factors when a small, closed set of items is used. According to this view, because the subject knows the set of items, there will be no effect of item information. In contrast, the impurity principle predicts that such effects can still be observed, because immediate serial recall with a small closed set of items is not a pure test of order information. Four experiments tested this edge case. In Experiments 1 and 2, we found concreteness effects when item uncertainty was minimized in both within-subjects (Exp. 1) and between-subjects (Exp. 2) designs. In Experiments 3 and 4, we found frequency effects when item uncertainty was minimized in both within-subjects (Exp. 3) and between-subjects (Exp. 4) designs. Analyses of intrusion and omission errors indicated that the sets of items had been learned. Analyses by experiment half also confirmed that the effects of concreteness and frequency were observable in the latter stages of the experiments, when there should have been even less doubt about the items. The results support the impurity principle and suggest that hesitation about accepting it in edge cases is unwarranted.

Links Between Short-Term Memory and Word Retrieval in Aphasia

PURPOSE

This study explored the relationship between anomia and verbal short-term memory (STM) in the context of an interactive activation language processing model.

METHOD

Twenty-four individuals with aphasia and reduced STM spans (i.e., impaired immediate serial recall of words) completed a picture-naming task and a word pair repetition task (a measure of verbal STM). Correlations between verbal STM and word retrieval errors made on the picture-naming task were examined.

RESULTS

A significant positive correlation between naming accuracy and verbal span length was found. More intricate verbal STM analyses examined the relationship between picture-naming error types (i.e., semantic vs. phonological) and 2 measures of verbal STM: (a) location of errors on the word pair repetition task and (b) imageability and frequency effects on the word pair repetition task. Results indicated that, as phonological word retrieval errors (relative to semantic) increase, bias toward correct repetition of high-imageability words increases.

CONCLUSIONS

Results suggest that word retrieval and verbal STM tasks likely rely on a partially shared temporary linguistic activation process.

Does neighborhood size really cause the word length effect?

In short-term serial recall, it is well-known that short words are remembered better than long words. This word length effect has been the cornerstone of the working memory model and a benchmark effect that all models of immediate memory should account for. Currently, there is no consensus as to what determines the word length effect. Jalbert and colleagues (Jalbert, Neath, Bireta, & Surprenant, 2011a; Jalbert, Neath, & Surprenant, 2011b) suggested that neighborhood size is one causal factor. In six experiments we systematically examined their suggestion. In Experiment 1, with an immediate serial recall task, multiple word lengths, and a large pool of words controlled for neighborhood size, the typical word length effect was present. In Experiments 2 and 3, with an order reconstruction task and words with either many or few neighbors, we observed the typical word length effect. In Experiment 4 we tested the hypothesis that the previous abolition of the word length effect when neighborhood size was controlled was due to a confounded factor: frequency of orthographic structure. As predicted, we reversed the word length effect when using short words with less frequent orthographic structures than the long words, as was done in both of Jalbert et al.'s studies. In Experiments 5 and 6, we again observed the typical word length effect, even if we controlled for neighborhood size and frequency of orthographic structure. Overall, the results were not consistent with the predictions of Jalbert et al. and clearly showed a large and reliable word length effect after controlling for neighborhood size.

The Hopkins Verbal Learning Test: an in-depth analysis of recall patterns

One of the earliest signs of dementia is memory issues and verbal word lists, such as the Hopkins Verbal Learning Test (HVLT), are successfully used for screening. To gain insight in how memory is affected in dementia, and to further improve the efficacy of the HVLT, in-depth analysis of the recall patterns of dementia cases and controls was conducted. Dementia cases and controls were matched for factors that can affect performance, such as age, gender and education level. Word frequency, syllable length, and orthographic neighbourhood size did not differ in the Indonesian version of the HVLT, nor did these characteristics affect recall. However dementia cases showed consistent and poor recall across the three trials; with the worst recall for the "human shelter" category and best recall for the "animals" category. Dementia cases also showed impaired accessibility of all categories with reduced subsequent recall from accessed categories and reduced primacy and recency levels. Finally, dementia cases exhibited lower levels of re-remembering and recalling new words, and higher levels of immediate forgetting and never recalling words. It was concluded that utilising the extra information provided by the in-depth analyses of the recall patterns could be beneficial to improve dementia screening.

Prosodic Similarity Effects in Short-Term Memory in Developmental Dyslexia

Children with developmental dyslexia are characterized by phonological difficulties across languages. Classically, this 'phonological deficit' in dyslexia has been investigated with tasks using single-syllable words. Recently, however, several studies have demonstrated difficulties in prosodic awareness in dyslexia. Potential prosodic effects in short-term memory have not yet been investigated. Here we create a new instrument based on three-syllable words that vary in stress patterns, to investigate whether prosodic similarity (the same prosodic pattern of stressed and unstressed syllables) exerts systematic effects on short-term memory. We study participants with dyslexia and age-matched and younger reading-level-matched typically developing controls. We find that all participants, including dyslexic participants, show prosodic similarity effects in short-term memory. All participants exhibited better retention of words that differed in prosodic structure, although participants with dyslexia recalled fewer words accurately overall compared to age-matched controls. Individual differences in prosodic memory were predicted by earlier vocabulary abilities, by earlier sensitivity to syllable stress and by earlier phonological awareness. To our knowledge, this is the first demonstration of prosodic similarity effects in short-term memory. The implications of a prosodic similarity effect for theories of lexical representation and of dyslexia are discussed. © 2016 The Authors. Dyslexia published by John Wiley & Sons Ltd.

The Effects of Phonotactic Probability and Neighborhood Density on Adults' Word Learning in Noisy Conditions

PURPOSE

Noisy conditions make auditory processing difficult. This study explores whether noisy conditions influence the effects of phonotactic probability (the likelihood of occurrence of a sound sequence) and neighborhood density (phonological similarity among words) on adults' word learning.

METHOD

Fifty-eight adults learned nonwords varying in phonotactic probability and neighborhood density in either an unfavorable (0-dB signal-to-noise ratio [SNR]) or a favorable (+8-dB SNR) listening condition. Word learning was assessed using a picture naming task by scoring the proportion of phonemes named correctly.

RESULTS

The unfavorable 0-dB SNR condition showed a significant interaction between phonotactic probability and neighborhood density in the absence of main effects. In particular, adults learned more words when phonotactic probability and neighborhood density were both low or both high. The +8-dB SNR condition did not show this interaction. These results are inconsistent with those from a prior adult word learning study conducted under quiet listening conditions that showed main effects of word characteristics.

CONCLUSIONS

As the listening condition worsens, adult word learning benefits from a convergence of phonotactic probability and neighborhood density. Clinical implications are discussed for potential populations who experience difficulty with auditory perception or processing, making them more vulnerable to noise.

Differential recall of derived and inflected word forms in working memory: examining the role of morphological information in simple and complex working memory tasks

Working memory (WM) has been described as an interface between cognition and action, or a system for access to a limited amount of information needed in complex cognition. Access to morphological information is needed for comprehending and producing sentences. The present study probed WM for morphologically complex word forms in Finnish, a morphologically rich language. We studied monomorphemic (boy), inflected (boy+'s), and derived (boy+hood) words in three tasks. Simple span, immediate serial recall of words, in Experiment 1, is assumed to mainly rely on information in the focus of attention. Sentence span, a dual task combining sentence reading with recall of the last word (Experiment 2) or of a word not included in the sentence (Experiment 3) is assumed to involve establishment of a search set in long-term memory for fast activation into the focus of attention. Recall was best for monomorphemic and worst for inflected word forms with performance on derived words in between. However, there was an interaction between word type and experiment, suggesting that complex span is more sensitive to morphological complexity in derivations than simple span. This was explored in a within-subjects Experiment 4 combining all three tasks. An interaction between morphological complexity and task was replicated. Both inflected and derived forms increased load in WM. In simple span, recall of inflectional forms resulted in form errors. Complex span tasks were more sensitive to morphological load in derived words, possibly resulting from interference from morphological neighbors in the mental lexicon. The results are best understood as involving competition among inflectional forms when binding words from input into an output structure, and competition from morphological neighbors in secondary memory during cumulative retrieval-encoding cycles. Models of verbal recall need to be able to represent morphological as well as phonological and semantic information.

Phi-square Lexical Competition Database (Phi-Lex): an online tool for quantifying auditory and visual lexical competition

A widely agreed-upon feature of spoken word recognition is that multiple lexical candidates in memory are simultaneously activated in parallel when a listener hears a word, and that those candidates compete for recognition (Luce, Goldinger, Auer, & Vitevitch, Perception 62:615-625, 2000; Luce & Pisoni, Ear and Hearing 19:1-36, 1998; McClelland & Elman, Cognitive Psychology 18:1-86, 1986). Because the presence of those competitors influences word recognition, much research has sought to quantify the processes of lexical competition. Metrics that quantify lexical competition continuously are more effective predictors of auditory and visual (lipread) spoken word recognition than are the categorical metrics traditionally used (Feld & Sommers, Speech Communication 53:220-228, 2011; Strand & Sommers, Journal of the Acoustical Society of America 130:1663-1672, 2011). A limitation of the continuous metrics is that they are somewhat computationally cumbersome and require access to existing speech databases. This article describes the Phi-square Lexical Competition Database (Phi-Lex): an online, searchable database that provides access to multiple metrics of auditory and visual (lipread) lexical competition for English words, available at www.juliastrand.com/phi-lex .

Insights into failed lexical retrieval from network science

Previous network analyses of the phonological lexicon (Vitevitch, 2008) observed a web-like structure that exhibited assortative mixing by degree: words with dense phonological neighborhoods tend to have as neighbors words that also have dense phonological neighborhoods, and words with sparse phonological neighborhoods tend to have as neighbors words that also have sparse phonological neighborhoods. Given the role that assortative mixing by degree plays in network resilience, we examined instances of real and simulated lexical retrieval failures in computer simulations, analysis of a slips-of-the-ear corpus, and three psycholinguistic experiments for evidence of this network characteristic in human behavior. The results of the various analyses support the hypothesis that the structure of words in the mental lexicon influences lexical processing. The implications of network science for current models of spoken word recognition, language processing, and cognitive psychology more generally are discussed.

The effect of incremental changes in phonotactic probability and neighborhood density on word learning by preschool children

PURPOSE

Phonotactic probability or neighborhood density has predominately been defined through the use of gross distinctions (i.e., low vs. high). In the current studies, the authors examined the influence of finer changes in probability (Experiment 1) and density (Experiment 2) on word learning.

METHOD

The authors examined the full range of probability or density by sampling 5 nonwords from each of 4 quartiles. Three- and 5-year-old children received training on nonword-nonobject pairs. Learning was measured in a picture-naming task immediately following training and 1 week after training. Results were analyzed through the use of multilevel modeling.

RESULTS

A linear spline model best captured nonlinearities in phonotactic probability. Specifically, word learning improved as probability increased in the lowest quartile, worsened as probability increased in the mid-low quartile, and then remained stable and poor in the 2 highest quartiles. An ordinary linear model sufficiently described neighborhood density. Here, word learning improved as density increased across all quartiles.

CONCLUSION

Given these different patterns, phonotactic probability and neighborhood density appear to influence different word learning processes. Specifically, phonotactic probability may affect recognition that a sound sequence is an acceptable word in the language and is a novel word for the child, whereas neighborhood density may influence creation of a new representation in long-term memory.

Modality exclusivity norms for 400 nouns: the relationship between perceptual experience and surface word form

We present modality exclusivity norms for 400 randomly selected noun concepts, for which participants provided perceptual strength ratings across five sensory modalities (i.e., hearing, taste, touch, smell, and vision). A comparison with previous norms showed that noun concepts are more multimodal than adjective concepts, as nouns tend to subsume multiple adjectival property concepts (e.g., perceptual experience of the concept baby involves auditory, haptic, olfactory, and visual properties, and hence leads to multimodal perceptual strength). To show the value of these norms, we then used them to test a prediction of the sound symbolism hypothesis: Analysis revealed a systematic relationship between strength of perceptual experience in the referent concept and surface word form, such that distinctive perceptual experience tends to attract distinctive lexical labels. In other words, modality-specific norms of perceptual strength are useful for exploring not just the nature of grounded concepts, but also the nature of form-meaning relationships. These norms will be of benefit to those interested in the representational nature of concepts, the roles of perceptual information in word processing and in grounded cognition more generally, and the relationship between form and meaning in language development and evolution.

Rapid naming by children with and without specific language impairment

PURPOSE

Previous studies have reported that children with specific language impairment (SLI) name pictures more slowly than do chronological age-matched (CAM) peers. Rapid naming depends on 2 factors known to be problematic for children with SLI-lexical retrieval and nonlinguistic speed of processing. Although all studies implicate a speed-of-processing deficit as a contributing factor, researchers do not agree on the influence of language factors. The purpose of the current study was to explore word frequency (WF) and phonotactic pattern frequency (PPF) as potential lexical factors contributing to the naming deficits experienced by children with SLI.

METHOD

Three groups of children-20 children with SLI (Mage = 9;8 [years;months]), 20 younger vocabulary-matched (VM) controls, and 20 CAM controls-named pictures whose labels varied by WF and PPF.

RESULTS

Reaction time results revealed significant main effects of group (CAM < SLI = VM) and WF (high WF < low WF). Effects due to WF were comparable for all groups, but a significant Group × PPF interaction revealed that PPF effects were greater for children with SLI than for VM or CAM children.

CONCLUSION

Results replicate previous findings of a naming deficit in children with SLI. Furthermore, results suggest that children with SLI are more vulnerable to increased competition from words with frequent phonotactic patterns, which also come from dense phonological neighborhoods.

Phonological and lexical effects in verbal recall by children with specific language impairments

BACKGROUND & AIMS

The present study examined how phonological and lexical knowledge influences memory in children with specific language impairments (SLI). Previous work showed recall advantages for typical adults and children due to word frequency and phonotactic pattern frequency and a recall disadvantage due to phonological similarity among words. While children with SLI have well-documented memory difficulties, it is not clear whether these language knowledge factors also influence recall in this population.

METHODS & PROCEDURES

Sixteen children with SLI (mean age = 10;2) and chronological age-matched typically developing children (CAM) controls recalled lists of words differing in phonological similarity, word frequency and phonotactic pattern frequency. While previous studies used a small set of words appearing in multiple word lists, the current study used a larger set of words, without replacement, so that children could not gain practice with individual test items.

OUTCOMES & RESULTS

All main effects were significant. Interactions revealed that children with SLI were affected by similarity, but less so than their peers, comparably affected by word frequency and unaffected by phonotactic pattern frequency.

CONCLUSIONS & IMPLICATIONS

Results due to phonological similarity suggest that children with SLI use less efficient encoding, while results due to word frequency and phonotactic pattern frequency were mixed. Children with SLI used coarse-grained language knowledge (word frequency) comparably with peers, but were less able to use fine-grained knowledge (phonotactic pattern frequency). Paired with phonological similarity results, this suggests that children with SLI have difficulty establishing robust phonological knowledge for use in language tasks.

Complex network structure influences processing in long-term and short-term memory

Complex networks describe how entities in systems interact; the structure of such networks is argued to influence processing. One measure of network structure, clustering coefficient, C, measures the extent to which neighbors of a node are also neighbors of each other. Previous psycholinguistic experiments found that the C of phonological word-forms influenced retrieval from the mental lexicon (that portion of long-term memory dedicated to language) during the on-line recognition and production of spoken words. In the present study we examined how network structure influences other retrieval processes in long- and short-term memory. In a false-memory task-examining long-term memory-participants falsely recognized more words with low- than high-C. In a recognition memory task-examining veridical memories in long-term memory-participants correctly recognized more words with low- than high-C. However, participants in a serial recall task-examining redintegration in short-term memory-recalled lists comprised of high-C words more accurately than lists comprised of low-C words. These results demonstrate that network structure influences cognitive processes associated with several forms of memory including lexical, long-term, and short-term.

The Beginning Spanish Lexicon: A Web-based interface to calculate phonological similarity among Spanish words in adults learning Spanish as a foreign language

A number of resources provide psycholinguistic researchers with information about the words that the typical child or adult knows in a variety of languages. What is currently not available is a resource that provides information about the words that a typical adult learning a foreign language knows. We created such a resource for Spanish: The Beginning Spanish Lexicon. The present report describes the words contained in this web-accessible resource, and the information about those words provided by the interface. This information is freely accessible at: http://www.people.ku.edu/~mvitevit/BegSpanLex.html.

Slave systems in verbal short-term memory

BACKGROUND

The model of performance in short-term memory (STM) tasks that has been most influential in cognitive neuropsychological work on deficits of STM is the "working memory" model mainly associated with the work of Alan Baddeley and his colleagues.

AIM

This paper reviews the model. We examine the development of this theory in studies that account for STM performances in normal (non-brain-damaged) individuals, and then review the application of this theory to neuropsychological cases and specifications, modifications, and extensions of the theory that have been suggested on the basis of these cases. Our approach is to identify the major phenomena that have been discussed and to examine selected papers dealing with those phenomena in some detail.

MAIN CONTRIBUTION

The main contribution is a review of the WM model that includes both normative and neuropsychological data.

CONCLUSIONS

We conclude that the WM model has many inconsistencies and empirical inadequacies, and that cognitive neuropsychologists might benefit from considering other models when they attempt to describe and explain patients' performances on STM tasks.

Simulating retrieval from a highly clustered network: implications for spoken word recognition

Network science describes how entities in complex systems interact, and argues that the structure of the network influences processing. Clustering coefficient, C – one measure of network structure – refers to the extent to which neighbors of a node are also neighbors of each other. Previous simulations suggest that networks with low C dissipate information (or disease) to a large portion of the network, whereas in networks with high C information (or disease) tends to be constrained to a smaller portion of the network (Newman, 2003). In the present simulation we examined how C influenced the spread of activation to a specific node, simulating retrieval of a specific lexical item in a phonological network. The results of the network simulation showed that words with lower C had higher activation values (indicating faster or more accurate retrieval from the lexicon) than words with higher C. These results suggest that a simple mechanism for lexical retrieval can account for the observations made in Chan and Vitevitch (2009), and have implications for diffusion dynamics in other fields.

Strong and long: Effects of word length on phonological binding in verbal short-term memory

This study examined the effects of item length on the contribution of linguistic knowledge to immediate serial recall (ISR). Long words are typically recalled more poorly than short words, reflecting the greater demands that they place on phonological encoding, rehearsal, and production. However, reverse word length effects—that is, better recall of long than short words—can also occur in situations in which phonological maintenance is difficult, suggesting that long words derive greater support from long-term lexical knowledge. In this study, long and short words and nonwords (containing one vs. three syllables) were presented for immediate serial recall in (a) pure lists and (b) unpredictable mixed lists of words and nonwords. The mixed-list paradigm is known to disrupt the phonological stability of words, encouraging their phonemes to recombine with the elements of other list items. In this situation, standard length effects were seen for nonwords, while length effects for words were absent or reversed. A detailed error analysis revealed that long words were more robust to the mixed-list manipulation than short words: Their phonemes were less likely to be omitted and to recombine with phonemes from other list items. These findings support an interactive view of short-term memory, in which long words derive greater benefits from lexical knowledge than short words—especially when their phonological integrity is challenged by the inclusion of nonwords in mixed lists.

Lexicality and frequency in specific language impairment: accuracy and error data from two nonword repetition tests

PURPOSE

Deficits in phonological working memory and deficits in phonological processing have both been considered potential explanatory factors in specific language impairment (SLI). Manipulations of the lexicality and phonotactic frequency of nonwords enable contrasting predictions to be derived from these hypotheses.

METHOD

Eighteen typically developing (TD) children and 18 children with SLI completed an assessment battery that included tests of language ability, nonverbal intelligence, and two nonword repetition tests that varied in lexicality and frequency.

RESULTS

Repetition accuracy showed that children with SLI were unimpaired for short and simple high-lexicality nonwords, whereas clear impairments were shown for all low-lexicality nonwords. For low-lexicality nonwords, greater repetition accuracy was seen for nonwords constructed from high over low-frequency phoneme sequences. Children with SLI made the same proportion of errors that substituted a nonsense syllable for a lexical item as TD children, and this was stable across nonword length.

CONCLUSIONS

The data show support for a phonological processing deficit in children with SLI, where long-term lexical and sublexical phonological knowledge mediate the interpretation of nonwords. However, the data also suggest that while phonological processing may provide a key explanation of SLI, a full account is likely to be multifaceted.

Serial and free recall in children can be improved by training: evidence for the importance of phonological and semantic representations in immediate memory tasks

Children were assigned to three groups given training on unfamiliar words--phoneme-awareness training, rhyme training, and vocabulary training--and an untrained control group. Before and after training, we assessed the children's performance on serial- and free-recall tasks with these words, as well as their ability to define the words, manipulate phonemes in them, and generate rhymes for them. We found that phoneme-awareness training improved serial recall substantially and improved free recall to a lesser extent. In contrast, vocabulary training produced a substantial increase in free recall and a lesser increase in serial recall. These effects on recall were specific and did not generalize to untrained words. Rhyme training produced increases in rhyming skills but no increase in either serial or free recall. We argue that serial and free recall depend on common memory mechanisms, but serial recall relies more on phonological codes and free recall relies more on semantic codes.