Phonological Loop Research Articles

Working memory multicomponent model outcomes in individuals with traumatic brain injury: Critical review and meta-analysis.

Traumatic Brain Injury (TBI) often leads to cognitive impairments, particularly regarding working memory (WM). This meta-analysis aims to examine the impact of TBI on WM, taking into account moderating factors which has received little attention in previous research, such as severity of injury, the different domains of Baddeley's multi-component model, and the interaction between these two factors, as well as the interaction with other domains of executive functions. Following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, a systematic review and meta-analysis searched Google Scholar, PubMed, and PsycNET for studies with objective WM measures. Multiple meta-analyses were performed to compare the effects of TBI severity on different WM components. Twenty-four English, peer-reviewed articles, mostly cross-sectional were included. TBI significantly impairs general WM and all Baddeley's model components, most notably the Central Executive (d' = 0.74). Severity categories, mild-moderate and moderate-severe, were identified. Impairment was found across severities, with "moderate-severe" demonstrating the largest effect size (d' = 0.81). Individuals with moderate-severe TBI showed greater impairments in the Central Executive and Episodic Buffer compared to those with mild-moderate injury, whereas no such differences were found for the Phonological Loop and Visuospatial Sketchpad. These findings enhance our understanding of WM deficits in varying severities of TBI, highlighting the importance of assessing and treating WM in clinical practice and intervention planning.

The Working Memory Model and the relationship between immediate serial recall and immediate free recall.

The effects of speech-based variables on the immediate serial recall (ISR) task constitute fundamental evidence underpinning the concept of the Phonological Loop component of Working Memory. Somewhat surprisingly, the Phonological Loop has yet to be applied to the immediate free recall (IFR) task although both tasks share similar memoranda and presentation methods. We believe that the separation of theories of ISR and IFR has contributed to the historical divergence between the Working Memory and Episodic Memory literature. We review more recent evidence showing that the two tasks are approached by participants in similar ways, with similar encoding and rehearsal strategies, and are similarly affected by manipulations of word length, phonological similarity, articulatory suppression/concurrent articulation, and irrelevant speech/sound. We present new analyses showing that the outputs of the two tasks share similar runs of successive items that include the first and last items- which we term start- and end-sequences, respectively-that the remaining residual items exhibit strong recency effects, and that start- and end-sequences impose constraints on output order that help account for error transposition gradients in ISR. Such analyses suggest that similar mechanisms might convey serial order information in the two tasks. We believe that recency effects are often under-appreciated in theories of ISR, and IFR mechanisms could generate error transpositions. We hope that our review and new analyses encourage greater theoretical integration between ISR and IFR and between the Working Memory and Episodic Memory literature.

A comparison of working memory abilities between children with intellectual disability with non-specific aetiology and children with Down syndrome in schools for intellectual development in Germany

Objectives The study compares the working memory performance of students with Down syndrome (DS) to that of matched controls with non-specific intellectual disability (NSID). Even though empirical evidence is somewhat mixed and inconclusive, previous research suggests that students with DS display a relative weakness in the phonological loop. In contrast, no differences are reported in the visuo-spatial sketchpad and the central executive. Methods The sample consisted of 23 students with DS and 23 matched controls with NSID. The phonological loop was assessed using nonword repetition and picture span. Measures of the visuo-spatial sketchpad included a corsi-block task and a pattern span. Finally, an odd-one-out task was used to assess the executive-loaded working memory (ELWM) as a part of the central executive. Results Supporting our hypotheses, students with DS significantly differed from their peers with NSID in the phonological loop, while we found no performance differences for the visuo-spatial sketchpad and the ELWM. Conclusions Weaknesses in the phonological loop in students with DS are documented in literature and supported by this study. Important conclusions can be drawn for teachers’ instruction and students’ reading development. However, the study’s limitations mean that any inferences must be drawn cautiously.

Association between working memory performance and parent and teacher ratings of working memory in 11-year-old children born preterm

ABSTRACT Working memory (WM) difficulties are often observed in children born preterm. We examined whether performance-based measures of WM components are associated with parent- and teacher-rated WM difficulties in the everyday life of children born very preterm and/or at very low birth weight (VPT/VLBW) at 11 years (n = 165). The WM components as defined in the original Baddeley’s model – phonological loop (PL), visuospatial sketchpad (VS), and central executive (CE) – were assessed with tasks from the Working Memory Test Battery for Children (WMTB-C) and the Wechsler Intelligence Scale for Children – Fourth edition (WISC-IV). Parents and teachers completed the WM subscale of the Behavioral Rating Inventory for Executive Functions (BRIEF). Measures of WM components were modestly associated with BRIEF scores, explaining 18.9% of the variance in parent-rated and 14.0% of teacher-rated WM difficulties. CE was the component most consistently associated with parent- and teacher-rated everyday WM. To conclude, our results suggest that tasks that utilize CE functions may best reflect WM outside of controlled test settings in the follow-up of VPT/VLBW children. However, performance and rating-scale measures provide unique information and are both needed to comprehensively assess WM skills.

Contrasting Deficits in the Function of the Phonological Loop Between Children With Attention Deficit Hyperactivity Disorder and Reading Disability.

Attention Deficit Hyperactivity Disorder (ADHD) and reading disability (RD) often co-occur. Impairments in the phonological loop of working memory are central to RD, but it is unclear whether this is linked to ADHD, especially in Chinese reading. Two experiments were conducted with Chinese children aged 7 to 12 (Experiment 1, n = 65; Experiment 2, n = 60). Immediate and delayed recognition paradigms were used to assess phonological encoding and rehearsal. Both the RD-only and comorbid (ADHD + RD) groups performed worse than the control and ADHD-only groups in response time and accuracy. Notably, the comorbid group performed similarly to the RD-only group, indicating that phonological loop deficits in comorbid children are likely due to RD, not ADHD. This highlights phonological loop function as the key to distinguishing between ADHD and RD.

Differences in working memory function are associated with motor imagery-induced changes in spinal motor nerve excitability and subsequent motor skill changes.

Verification of the effectiveness of motor imagery (MI) has mainly focused on the method of implementing MI, and few studies have assessed individual factors. This study examined the individual differences in MI effects from the viewpoint of the multiple components of working memory. Forty-six healthy subjects (mean age 20.8years) performed the Stroop Test (central executive within working memory) and reverse chanting (phonological loop within working memory). Then, F-waves were measured at rest for 30s, the Purdue Pegboard was performed with the non-dominant hand to evaluate finger dexterity (Peg score) before MI, F-waves were measured during 30s of kinesthetic MI, and the Peg score was evaluated after MI. For statistical analysis, the amplitude F/M ratio and Peg score were used as dependent variables, and the subjects were divided into Good and Poor groups according to cognitive function. The results showed an interaction for the amplitude F/M ratio and Peg score when grouped by reverseinverse chanting. In the subsequent simple main effect analysis, the Peg score was significantly improved after MI in both groups. The amplitude F/M ratio was significantly increased during MI compared to the resting state only in the Poor phonological loop group. Conversely, there was no interaction when the groups were divided by Stroop interference. No relationship was found between individual differences in central executive and changes in hand finger dexterity and spinal motor nerve excitability induced by MI. However, there may be a relationship between individual differences in phonological loops and changes in MI-induced finger dexterity and spinal motor nerve excitability.

A - 37 ADHD-Related Hyperactivity and Impulsivity: Distinct or Overlapping Dimensions?

Abstract Objective It is debated whether hyperactivity and impulsivity should remain combined within the (DSM) hyperactivity/impulsivity domain or be separated. To address this dispute, we sought to determine whether hyperactivity and impulsivity are differentially related to executive functioning (EF), a common deficit area in ADHD. Method Participants included 120 children (ages 8–11; 89.9% White; 51.6% girls) from a community sample tested in a laboratory setting. To be included, they must have ADHD (59.4%) or be typically developing (40.6%). Hyperactivity and impulsivity scales were created from symptoms from a parent-report Behavior Assessment System for Children and DSM-IV questionnaire, ADHD section. The Behavior Rating Inventory of Executive Functioning (BRIEF) Working Memory scale (WMsc) and the Children’s Memory Scale Picture Locations (visuospatial sketchpad), Numbers Forward (phonological loop), and Sequences (central executive) subtests were used to assess working memory (WM). Inhibition was assessed with the BRIEF Inhibition scale (Isc) and A Developmental Neuropsychological Assessment (NEPSY) Tower Rule Violations (RV). Emotional control (EC) was measured with the BRIEF’s EC scale. Results Confirmatory linear regressions (SPSS Enter method) with all EF measures as IVs revealed Isc and WMsc were significant predictors of impulsivity [F(7,120) = 24.85, p < 0.001]. For hyperactivity [F(7,120) = 21.40, p < 0.001], WMsc, Isc, and RV were significant predictors. Exploratory analyses revealed WMsc was related to hyperactivity in controls but impulsivity in ADHD. Conclusions Similarities and differences were found between hyperactivity and impulsivity in relation to EF. Whereas inhibition was similarly related to hyperactivity and impulsivity, WM’s relationships were dissociable between groups. Hence, further research is needed, including areas affected in ADHD besides EF.

Utility Prospect of the Working Memory Model in Whispered Interpreting - the Case Study in “Nanning Tour” at the 20th China-ASEAN Expo as an Example

This study examines whispered interpreting (WI), where interpreters translate spoken language in real-time at a soft volume. It underscores the Working Memory Model’s (WMM) utility in such tasks, which demand intense cognitive effort. A practical example from the 2023 China-ASEAN Expo showcases the model’s mechanisms enhancing interpreting efficiency. The phonological loop processes verbal information, the visuo-spatial sketchpad handles visual cues, and the episodic buffer consolidates complex data. Managed by the central executive, these elements collectively lighten the cognitive load and boost performance. The paper reveals WMM’s untapped potential, advocating for deeper investigation into its application in WI.

Can Brief Listening to Mozart's Music Improve Visual Working Memory? An Update on the Role of Cognitive and Emotional Factors.

The aim of this research was to enhance understanding of the relationship between brief music listening and working memory (WM) functions. The study extends a previous large-scale experiment in which the effects of brief exposure to music on verbal WM were explored. In the present second phase of the experiment, these effects were assessed for the visuospatial subcomponent of WM. For that aim, visuospatial WM was measured using the Corsi blocks task-backwards and Visual Patterns Test in a large sample of 311 young and older adults after being exposed to musical excerpts coming from different music composers (Mozart, Vivaldi, Glass). To account for possible effects of arousal, a silence condition was used. Individual preference for music excerpts and emotional reactions to each condition were also subjectively rated using the Positive and Negative Affect Schedule (PANAS) to account for the role of emotional reactions in shaping subsequent cognitive performance. Results showed that music affected the visuospatial sketchpad of WM. In line with the previously described Mozart effect, only Mozart's music had a significant positive impact on visuospatial WM in the two age groups, regardless of preferences, and on overall age-related WM decline in older adults. The Mozart effect was more prominent for the VPT than the Corsi task and was also expressed for the prevailing positive effect. These observations are in contrast to the selective influence of Vivaldi's music on verbal WM that was detected in our first study. Together, the results demonstrate a differential music influence on the phonological loop and on the visuospatial sketchpad. They thus contribute to the debate of whether music has the potential to affect distinct processes within working memory in an excerpt- or composer-specific manner. Also, they suggest that emotional activation and central executive attention are essentially involved in modulating the influence of music on subsequent cognition. These findings can assist in the selection of music excerpts used in cognitive rehabilitation programs that focus on visuospatial skills.

What's in a name: The role of verbalization in reinforcement learning.

(e.g., characters or fractals) and concrete stimuli (e.g., pictures of everyday objects) are used interchangeably in the reinforcement-learning literature. Yet, it is unclear whether the same learning processes underlie learning from these different stimulus types. In two preregistered experiments (N = 50 each), we assessed whether abstract and concrete stimuli yield different reinforcement-learning performance and whether this difference can be explained by verbalization. We argued that concrete stimuli are easier to verbalize than abstract ones, and that people therefore can appeal to the phonological loop, a subcomponent of the working-memory system responsible for storing and rehearsing verbal information, while learning. To test whether this verbalization aids reinforcement-learning performance, we administered a reinforcement-learning task in which participants learned either abstract or concrete stimuli while verbalization was hindered or not. In the first experiment, results showed a more pronounced detrimental effect of hindered verbalization for concrete than abstract stimuli on response times, but not on accuracy. In the second experiment, in which we reduced the response window, results showed the differential effect of hindered verbalization between stimulus types on accuracy, not on response times. These results imply that verbalization aids learning for concrete, but not abstract, stimuli and therefore that different processes underlie learning from these types of stimuli. This emphasizes the importance of carefully considering stimulus types. We discuss these findings in light of generalizability and validity of reinforcement-learning research.

Examining the role of the visuospatial sketchpad in children's math calculation skills using Baddeley and Hitch's model of working memory

Math difficulties (MDs) occur in about 3–7 % of children and have been associated with academic, health, and occupational challenges. To date, findings about the role of working memory in MDs have been conflicting. The Automated Working Memory Assessment Battery (AWMA), which assesses all components of Baddeley and Hitch's model of working memory, was used to investigate which component of the model was most related to math calculation skills in elementary-school children. Participants were 94 (52 male) children (M age = 9 years 1 month; Range = 6 years 0 months to 11 years 8 months). As hypothesized, math calculation scores were correlated with all four working memory components (phonological loop, visuospatial sketchpad, verbal and visuospatial central executive). After accounting for age, phonological processing, and attention, the visuospatial sketchpad was the only memory component that contributed to the prediction of math calculation scores, explaining an additional 10.2 % of unique variance. Short-term visuospatial memory should be assessed in children having difficulty with math and children could benefit from interventions that include attention to the development of both visuospatial memory and math calculation skills. This study did not use a longitudinal design and so we cannot conclude that weak visuospatial memory impedes the development of math calculation skills. Future research should use longitudinal designs and investigate other types of math skills.

Working memory components modulation of attentional disengagement from evaluative distractor.

It is important for people to disengage attention from a distraction, which can help them complete the task at hand as quickly as possible. Recent studies have shown that people's attention stays longer on reward-distractors than on loss-distractors, and a delay in attentional disengagement is noted when reward-distractors are present. However, few studies have examined whether attentional disengagement from an evaluative distractor relies upon working memory (WM) components. In the present study, we used an attentional disengagement paradigm in which reward- or loss-distractors were presented at a central location and the target was presented at a peripheral location, in combination with different WM tasks. The results from Experiment 1 showed that participants were slower to disengage their attention from a central reward-distractor than a loss-distractor regardless of cognitive load when the phonological loop component of WM was involved. The results from Experiment 2 revealed that people had difficulty in shifting their attention away from a reward-distractor in comparison to a loss-distractor when spatial WM was low, whereas no such difference was observed when spatial WM was high. We conclude that WM components differently modulate attentional disengagement from evaluative distractors. That is, the processing of evaluative (reward and loss) distractors may rely on the same cognitive resources as the spatial WM component, but not the phonological loop component.

Working memory program for improving language skills in older adults with mild neurocognitive disorders: A pilot study

Background: Older adults with mild neurocognitive disorders (mild NCD) have a higher risk of major NCD. Cognitive deterioration can cause a deficit in working memory and language. Recent studies have shown some involvement overlapping the brain structure of working memory and language skills. Therefore, working memory intervention effectively enhances language skills in mild NCD. However, more research on this topic in Thailand is required. Objectives: This study aimed to develop and implement a pilot study on a working memory program for improving language skills in older adults with mild NCD. Materials and methods: This study was a developmental research design with two phases. Phase one involved the development and examination of the content validity of the working memory program for improving language skills by five experts. Phase two involved piloting the program with three older adults with mild NCD. The participants were asked to provide suggestions about the clarity of content and images, language usage, font size, the comprehensibility of instructions in each activity, and the quality of audio files used to complement the program activities through semi-structured interviews. Descriptive statistics were employed to analyze the collected data. Results: The program comprised nine activities associated with the phonological loop, visual-spatial sketchpad, episodic buffer, and central executive tasks. The program’s content validity was evaluated by five experts, resulting in a content validity index of 0.94, meeting the established criteria. Among the pilot users, three participants meeting the specified criteria indicated their ability to use and practice the program at home effectively. While most participants agreed that the images were clear and the font size was appropriate, there were concerns regarding the clarity of the training process steps and instructions. Additionally, some participants encountered challenges in accessing audio files through quick response (QR) codes. Conclusion: In summary, the pilot study of the working memory program for improving language skills in older adults with mild NCD passed the content validity test and underwent revisions based on suggestions from the pilot users. Consequently, the program could enhance the language abilities of older adults with mild NCD. The next phase will investigate its effectiveness in improving language skills in older adults with mild NCD.

Processamento auditivo central e processamento fonológico em bilíngues do português brasileiro - inglês

ABSTRACT Purpose: to compare temporal auditory processing (temporal ordering) and phonological processing skills in bilingual and monolingual subjects. Methods: 100 undergraduate and postgraduate university students divided into a bilingual group (BG; n = 50) and a monolingual group (MG; n = 50). The study assessed the two groups’ phonological processing skills (phonological awareness, working memory - phonological loop, and rapid lexicon access) and temporal auditory processing skills (Frequency Pattern and Duration Pattern Tests). The Mann-Whitney test (p = 0.05) was used for statistical analysis. Results: BG performed better than MG in phonological awareness and phonological working memory tasks - nonword repetition and rapid naming tasks, except for color naming, and the two auditory processing tests. Conclusion: Bilinguals performed better on phonological and auditory tests. These skills help them identify and discriminate variations in the phonology of both languages, influencing their performance.

New Working Memory Paradigm for Neuroimaging Testing of Visual and Verbal Modality under Different Attentional Involvement

Working memory (WM) is a cognitive function essential for short-term maintenance of information in a highly accessible state to support goal-directed behavior. The classical behavioral model of WM includes a visuospatial sketchpad, a phonological loop and the central executive. Neuroimaging studies selectively targeted the activity associated with maintenance and processing of modality specific information. However, an experimental design is still missing that would enable the assessment of all components of WM drawing a holistic neuroimaging model. In this study, we propose a modified paradigm based on the classical retro-cue task, which allows disentangling the activity of all WM components, and in particular of the central executive. This paradigm consists of five conditions: passive perception, simple verbal storage, simple visual storage, alphabetical reordering (complex verbal) and mental rotation (complex visual). Testing on a cohort of 35 healthy adults, we obtained a similar workload for simple storage conditions with a low engagement of the central executive. A different workload was verified between the simple and complex conditions in both verbal and visual modalities. This experimental design provides the framework to assess the neural activity associated with the central executive components in different modalities and to address the question of a unitary or modality-specific central executive nature. Therefore, the paradigm is suitable for utilization in neuroimaging to potentially advance our comprehension of the WM organization.

Neural mechanisms of sentence production: a volumetric study of primary progressive aphasia.

Studies on the neural bases of sentence production have yielded mixed results, partly due to differences in tasks and participant types. In this study, 101 individuals with primary progressive aphasia (PPA) were evaluated using a test that required spoken production following an auditory prime (Northwestern Assessment of Verbs and Sentences-Sentence Production Priming Test, NAVS-SPPT), and one that required building a sentence by ordering word cards (Northwestern Anagram Test, NAT). Voxel-Based Morphometry revealed that gray matter (GM) volume in left inferior/middle frontal gyri (L IFG/MFG) was associated with sentence production accuracy on both tasks, more so for complex sentences, whereas, GM volume in left posterior temporal regions was exclusively associated with NAVS-SPPT performance and predicted by performance on a Digit Span Forward (DSF) task. Verb retrieval deficits partly mediated the relationship between L IFG/MFG and performance on the NAVS-SPPT. These findings underscore the importance of L IFG/MFG for sentence production and suggest that this relationship is partly accounted for by verb retrieval deficits, but not phonological loop integrity. In contrast, it is possible that the posterior temporal cortex is associated with auditory short-term memory ability, to the extent that DSF performance is a valid measure of this in aphasia.

A Study of the Effect of Phonological Loop Suppression on TMT-B Test Performance

This study aimed to examine the impact of vocal music on cognitive performance using the Trail Making Test (TMT)-B. A sample of 90 participants was randomly assigned into two groups: one group listened to vocal music while completing the TMT-B, while the other group performed the task without any music. The TMT-B was specifically chosen as it incorporates the central executive, particularly the phonological loop, enabling more targeted findings. Our hypothesis posited that participants exposed to vocal music would exhibit lower performance on the TMT-B test due to the distraction caused and the suppression of the phonological loop. Statistical analysis was conducted using the Mann-Whitney U Test. Results revealed a significant difference in completion time between the two groups (with a large effect size d=0,95), with the group with vocal music taking longer to complete the test compared to the group without music. This suggests that vocal music interference has a negative impact on TMT-B performance. Keywords: Working memory • Phonological loop Suppression • Processing speed • Cognition • Trail Making Test

Phonological ability and neural congruency: Phonological loop or more?

ObjectiveWe explored neural components in Electroencephalography (EEG) signals during a phonological processing task to assess (a) the neural origins of Baddeley’s working-memory components contributing to phonological processing, (b) the unitary structure of phonological processing and (c) the neural differences between children with dyslexia (DYS) and controls (CAC). MethodsEEG data were collected from sixty children (half with dyslexia) while performing the initial- and final- phoneme elision task. We explored a novel machine-learning-based approach to identify the neural components in EEG elicited in response to the two conditions and capture differences between DYS and CAC. ResultsOur method identifies two sets of phoneme-related neural congruency components capturing neural activations distinguishing DYS and CAC across conditions. ConclusionsNeural congruency components capture the underlying neural mechanisms that drive the relationship between phonological deficits and dyslexia and provide insights into the phonological loop and visual-sketchpad dimensions in Baddeley’s model at the neural level. They also confirm the unitary structure of phonological awareness with EEG data. SignificanceOur findings provide novel insights into the neural origins of the phonological processing differences in children with dyslexia, the unitary structure of phonological awareness, and further verify Baddeley’s model as a theoretical framework for phonological processing and dyslexia.

Neuropsychological Assessment of the Relationship of Working Memory with K-BIT Matrices and Vocabulary in Normal Development and ADHD Children and Adolescents.

The present report tries to understand the possible relationship between working memory (WM) and intelligence measurements, using the direct scores of the Working Memory Test Battery for Children (WMTBC) and Kaufman's Brief Intelligence Test (K-BIT), in normal development (ND) and diagnosed attention deficit hyperactivity disorder (ADHD) children and adolescents. Partial correlations, discounting the effect of age, showed a significant correlation in ND subjects between the central executive (CE) component of WM and the WM visuospatial sketchpad (VSS) component and the WM phonological loop (PL); also, significant correlations were obtained for the WM VSS with the K-BIT Matrices scores, the WM PL with the K-BIT Vocabulary, and the K-BIT Matrices scores with the K-BIT Vocabulary. For ADHD subjects, there were significant correlations between WM VSS and WM CE, and WM VSS and K-BIT Matrices. We tested the robustness of these correlations by selecting a small number of subjects through permutations; a robust correlation between WM CE and WM PL in ND, and between WM VSS and WM CE and WM VSS and K-BIT Matrices scores was obtained. These results were also supported by mediation analysis. There is a relationship during development between WM as measured with WMTBC and general intelligence as measured with K-BIT in ND and ADHD subjects. The dysexecutive character of ADHD has been shown, given that by controlling for intelligence, the differences in WM performance between ND and ADHD disappear, except for WM CE. The results suggest that in ADHD subjects, the WM VSS component presents a more pivotal role during cognitive processing compared to ND subjects.

What Components of Working Memory Are Impaired in Children with Reading and/or Mathematics Difficulties?

Both reading difficulties (RD) and mathematics difficulties (MD) are common neurodevelopmental disorders. The co-occurrence of RD and MD, known as comorbid RDMD, is estimated to range between 21% and 45% of children with learning disabilities. Deficits in working memory have been reported in both RD and MD groups, as well as among comorbid RDMD. However, previous comorbidity studies have only examined the role of some components of working memory, and they do not strictly match their groups on relevant reading and mathematics tasks. Thus, the purpose of this study is to examine the nature of working memory deficits in comorbid RDMD after matching groups based on reading and mathematics tasks. We assessed four groups of children (RD [n = 21, Mage = 10.96 years], MD [n = 24, Mage = 11.04 years], comorbid RDMD [n = 26, Mage = 10.90 years], and chronological-age controls [n = 27, Mage = 10.96 years]) on measures of the phonological loop (word span and digit span forward tasks), central executive (complex word and digit span), and updating tasks (word and digit 2-back). The results of ANCOVA (covarying for gender and non-verbal IQ) showed first that the RD and RDMD groups performed significantly worse than the MD and control groups in both measures of the phonological loop. For the central executive and updating tasks, we found an effect based on stimulus type. For word-related tasks, the RD and comorbid RDMD groups performed worse than the MD and control groups, and for number-related tasks, the MD and comorbid RDMD groups performed worse than the RD and control groups. Taken together, our findings provide support for the correlated liability model of comorbidity, which indicates that working memory deficits experienced by the RDMD group are an additive combination of deficits observed in the RD and MD groups, suggesting that working memory tasks used to examine underlying deficits in reading and/or mathematics difficulties may dictate whether or not significant group differences are found.