Differences in Cognitive and Mathematical Skills of Students with a Mathematical Learning Disability and Those with Low Achievement in Mathematics: A Systematic Literature Review

Round 1

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

Thank you for the opportunity to review the paper. I enjoyed reading this. Please refer to the attached document for some suggestions on how to further improve the paper.

Comments for author File: Comments.pdf

Author Response

Comment 1:

The examples of the difficulties are added (marked with yellow in the article):

Moreover, students with MLD experience significant and persistent challenges especially in learning mathematics, including difficulties with number sense, accuracy and fluency in performing calculations, and engaging in mathematical reasoning (World Health Organization (WHO), 2019).

Comment 2:

We have rewritten the paragraph:

In this study, considering the diversity of definitions of math learning disability and low achievement, we interpret MLD as a specific learning disability with math test scores at or below the 10th percentile and take the terms “math learning disorder” and “math disability” as synonyms to MLD. Since dyscalculia also refers explicitly to difficulties in mathematics, especially when performing simple calculations (WHO, 2019), this article categorizes it as a type of MLD.

Comment 3:

To avoid this confusion, we have rephrased the sentence as follows:

According to Barnes & Raghubar (2017), domain-specific abilities are crucial developmental antecedents to eventual mathematical performance (e.g. complex calculation). However, domain-general abilities are essential in developing mathematical competencies (e.g., understanding and using mathematical concepts and procedures).

Comment 4:

We included the term "dyscalculia" in our literature search as one type of Mathematical Learning Disability (MLD). However, in this paper, we do not consider dyscalculia to be a direct synonym for MLD according to Geary's theory.

Comment 5:

All double-spaced lists and tables are reformatted and consistent with the rest of the paper.

Comment 6:

We have rephrased it as follows:

Permanence (the duration of low math test scores over the research period)

Comment 7:

We have changed persistency to permanence, which is now the same throughout the paper.

 

Comment 8:

Typical achievers are now included in the explanation of CG:

The students with MLD demonstrated significantly poorer performance in all three working memory components than the control group of typical achievers (CG).

A clarification regarding the control group has been included in the inclusion and exclusion criteria, where the control group is first mentioned in the article: “The typical achieving students as a control group were included in the study.”

Comment 9:

According to various studies, reasoning skills are strongly associated with mathematical performance. We have added a sentence adding to the connection between reasoning skills and mathematical performance:

For instance, Geary et al (2009) suggest that the relationship between IQ and number line performance in the first grade aligns with the capacity for logical and systematic thinking, which is essential for understanding the structure of the mathematical number line.

Comment 10:

We have added the paragraph to the Discussion section:

Visuospatial working memory plays a key role in domain-specific cognitive skills, such as understanding number sets and the number line (Geary et al., 2009). The weaker visuospatial working memory in students with MLD may explain why their difficulties in mathematics arise early, during the acquisition of these domain-specific skills (Eidlin-Levy & Rubinstein, 2007). In contrast, low-achieving students typically face challenges primarily when tackling more complex mathematical problems (Shaw, 2022).

Comment 11:

The sentence has been rephrased:

While deficits in verbal processing are common predictors of reading and/or writing disability (Farrell, 2013; Fletcher et al., 2007), impaired language skills also have a significant impact on learning mathematics (Butterworth, 2019; Hannell, 2005), similar to the effects of difficulties in visuospatial processing.

Comment 12:

We have added Table 3 to the Discussion section, which concludes the main differences in cognitive skills between MLD and LA students:

Table 3. Differences in domain-general cognitive skills, domain-specific cognitive skills, and math skills between the students with MLD and LA students

Domain-general cognitive skills

Domain-specific cognitive skills and math skills

-       Students with MLD have weaker visuospatial working memory compared to LA students. -       Students with MLD have weaker verbal working memory and verbal reasoning than typical achievers (CG), while LA students perform similarly to CG. -       In contrast, the central executive function of working memory in MLD students is similar to CG, whereas LA students show weaker performance. -       Students with MLD have weaker cognitive processing, slower processing speed, and poorer cognitive inhibition than CG, while LA students perform similarly to CG.

-       Students with MLD perform worse than LA students in symbolic magnitude comparison. -       Students with MLD perform worse than CG in non-symbolic magnitude comparison, number comprehension, counting, and number reading and writing, while LA students show no differences from CG. -       Students with MLD perform worse than LA students in basic calculation.

 

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

- There are some technical revision suggestions on the paper. The suggestions are on the paper. 

- The reviewer suggests that the discussion should explicitly discuss the answers to research questions.

- The reviewer suggests that the results section should guide the reader to understand the tables.

Comments for author File: Comments.pdf

Author Response

Comment 1:

There are some technical revision suggestions on the paper. The suggestions are on the paper.

All double-spaced lists and tables have now been reformatted and are consistent with the rest of the paper.

Comment 2:

- The reviewer suggests that the discussion should explicitly discuss the answers to research questions.

The table (Table 3) has been added to the Discussion section to summarize the differences in cognitive profiles of MLD and LA students.

Comment 3:

The reviewer suggests that the results section should guide the reader to understand the tables.

The first table concludes the characteristics of the included studies and is introduced to the reader at the beginning of the Results section:

… see Table 1, presenting the characteristics of the samples in the selected studies.

We have added the description of Table 2, where it is first mentioned:

See Table 2, which presents the cognitive abilities of the students with MLD, LA, and MLD+LA compared to each other and the control group.

Comment 4:

This is confusion in this paragraph. Could you please explain based on Figure 1 again?

“An interrater agreement was calculated using Cohen's kappa (k = 0.72). There was disagreement about eight articles, and a consensus was reached by discussion. One hundred nineteen studies were selected for further review. The second step was selection, based on criteria for inclusion and exclusion, by reading abstracts of the studies. The full text was reviewed when the abstract did not answer all criteria. The first author coded all articles, and the second author coded 58 of them.”

We suggest that the object of confusion could be the number of studies excluded in the first phase (1808) that is not mentioned in the paragraph. This is the sum of the eliminated duplicates (112) and studies that were outside the scope (1696). We added the sum into the text:

Initially, the first author reviewed the titles and keywords to eliminate duplicates (n=112) and studies that were clearly outside the scope (n=1696), altogether 1808 studies.

 

Comment 5:

Do you mean Standard Deviation? It is unclear.

L283-284 “MLD was defined as a specific learning disability with math test scores at or below the 10th percentile or at or below 1,5 SD on math test scores”.

We wrote the term in words and placed the abbreviation in parentheses:

MLD was defined as a specific learning disability with math test scores at or below the 10th percentile or at or below 1,5 standard deviations (SD) on math test scores.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

Thank you for the opportunity to review the manuscript, Differences in Cognitive and Mathematical Skills of Students with a Mathematical Learning Disability and those with Low Achievement in Mathematics: a Systematic Literature Review. This review aims to describe the differences in cognitive skills of students with learning disability and low- achieving students, as presented in recent literature. I appreciate the efforts in reviewing 55 related articles.  

 

Introduction: 

The introduction lays out the variability of definitions and categorizations between math LD and low achieving students. Introduction should include statement of difference and overlap between math LD and LA.  

What is the purpose of investigating these groups as distinct categories? Is there supporting literature regarding the value of cognitive profiling? Does this inform instruction?  

Do these groups respond to intervention differently? Overall, a theoretical or literature based justification to investigate the cognitive skills and math skills of these students in separate categories is needed to strengthen the argument for the need of this manuscript. 

 

Also to consider, many studies identify their sample as MD based on low math performance (not by a biological or cognitive profiles). The introduction needs to clarify how to distinguish between these groups. 

 

Domain general and domain specific cognitive skills are described in results. Need to define domain general and domain specific skills. Why is it important to investigate these areas? Defining these areas in the introduction helps to frame the results and discussion. 

 

 

Method: 

 

The search concluded in March 2021. Are there studies to include since then? 

A major oversight in the criteria was that age and grade level are not specifically described. “Younger” and “older” does not provide enough information to the reader. , 

 

Results: 

 

If the purpose of the article is to address variability in definition or help clarify cognitive profiles, it seems that reporting out the scores of these domain general and domain specific scores would be helpful to examine. Are there patterns in performance as reported by these studies? Table 1 does not seem to give useful information in the sense that it may already be expected that students with MLD and low achievement. This table would be more informative if combined with information from Appendix 3 (with specific scores and information) to address the point above. 

 

Additionally, descriptions of cognitive and math skills by age/grade would add significant impact to this review. Surely, cognitive and math skills vary across ages and significant differences between achievement groups may not appear significant in very early elementary grades. The lack of attention to the difference in age groups is a significant weakness, and recommendations of interventions are inappropriate based on the findings. 

 

The scope of the review (or description of results) does not support the comment that IQs of all 3 sample groups were lower. Was statistical analysis conducted to compare IQs of groups? How is this statement justified – if compiling data across studies, specific analysis should be conducted and reported. 

Reviewer 2 Report

Comments and Suggestions for Authors

This paper describes a systematic review exploring the differences in cognitive abilities between MLD children and LA children when learning maths. The review splits the outcomes into Domain-Specific and Domain-General cognitive abilities following Butterworth (2019), and this way can identify skills that may involve number or arithmetic processing and skills that may underpin a wider range of learning. The review found that while the MLD and LA students were performing below controls on domain-general skills, the MLD group performed even more poorly on domain-specific skills.

 

It was good to see the authors follow PRISMA guidelines, and in general, these appear to have been followed well. However, note that there are some inconsistencies with the numbers of papers found and included. For example, the section Study Selection on page 5 states that 91 studies were selected for further review, but then 34 were eliminated, leading to a sample of 55. The problem is that 91 - 34 is 57, and Figure 1 states that 36 studies were eliminated after further examination. So, it would be good to tidy this up on the paper. In addition, it would be good to see the number of duplicates removed included on Figure 1 and a further explanation of when 30 of the articles were checked by the second author. I think it was when deciding on the eligibility of the study, but this could be clearer in the writing. It is a shame that the inclusion was only up to March 2021, as this is now 3.5 years ago.

More importantly, I was surprised that the analysis included evidence only when differences between the groups had been found. I think this leads to an inflation of the differences rather than a reflection of understanding the differences between the studies. Essentially, the review’s conclusions may overstate that there are important differences where the evidence is much more inconsistent. While the table in Appendix 3 goes some way to show what was found when there were differences between MLD, LA, and the control groups. I’d prefer to see a table 1 outline whether the findings show a consistent pattern. So, not only those 6 studies found a difference, but also if there were studies that did not. Furthermore, as the sample sizes vary considerably across the studies, and while this is not a meta-analysis, it is useful to be clear whether findings are comparable. It should not just be a counting process - which much of the Results section is - but also consider the strength of the evidence.

 

As the manuscript points out in the Introduction and Limitations, one of the greatest difficulties with reviewing the literature is that there is little consensus on how to define MLD and LA, and often there is some overlap. The authors could make these issues easier to understand by including a table that outlines the important features of the articles included in their review. I would suggest looking at Table 1 in Mammarella et al. (2021) for an example of this. That paper describes previous work by stating the number of articles that use math scores below the 15th percentile, as well as important details such as the sample size. I also noticed that in Appendix 2, Study 6 Chong and Siegel (2008) has no numbers listed for students with MLD, LA, or MLD and LA, yet they are included in the table in Appendix 3 for comparisons with a control group. It would be useful to add more details here.

 

Overall, I found the writing in the article did not provide a strong critical evaluation of the literature and the findings. In particular, the Introduction tends to list research without explicitly outlining a point that is relevant to the current research. For example, the paragraph beginning on line 192 lists many studies that have found ‘deficits’ in cognitive skills in MLD children, but there is no clear argument as to whether these have been consistent findings or why so many possible deficits are found within this group. More generally, it was interesting that the term ‘deficit’ is used throughout the current manuscript and the included research articles, yet there was little discussion of the type of control group included. If a control group is of a similar age to the children with MLD, then it is much more difficult to conclude that there is a deficit; the children could be showing a delay akin to the performance of a younger child. Reading research has countered this by including reading ability match controls, that is, younger children reading at a similar ability. If the group of interest are different from those younger readers, this is stronger evidence of a deficit. It could be that none of the 55 studies included in this review also have ability matching but I think it is worth discussing as a limitation as it impacts what conclusions can be made, particularly when differentiating between those with MLD and LA. I think we would expect those with LA to be performing similar to younger children. Finally, the manuscript sometimes makes strong claims, and some are based on research that is over 10 years old. For example, the opening paragraph of the Introduction states that ‘teachers lack knowledge of effectively identifying and supporting students with mathematical difficulties’ but given that the evidence is from 2008 and 2014, it is not clear whether this is still the case and whether it is the same in all countries.

 

 

Minor comment: MLD and LA were used throughout the paper but on line 135, it is L.A.

 

Comments on the Quality of English Language

The manuscript was easy to follow and understand it just needs more critical evaluation throughout. Try to avoid listing research and think how they relate to an argument.