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Magnitude Processing in Developmental Dyscalculia: A Heterogeneous Learning Disability with Different Cognitive Profiles
Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Developmental dyscalculia (DD) is a learning disability that is characterized by severe difficulties with acquiring age-appropriate mathematical skills that cannot be attributed to insufficient education, language skills, or motivation. The prevalence rate is estimated at 3-6%, meaning that a substantial portion of the population struggles to learn mathematics to such a large degree that it affects overall well-being and academic prospects. However, our understanding of the etiology of DD is incomplete and there are competing hypotheses regarding the characteristics of DD and its underlying causal factors. The purpose of the current thesis is to contribute to our understanding of DD from the perspective of cognitive psychology and cognitive neuroscience. To this end, we identify children with DD to identify the cognitive determinants of DD that hamper their ability to learn basic mathematics. It is believed that human beings are endowed with an innate ability to represent numerosities, an ability phylogenetically shared with other species. We investigate whether the purported innate number system plays a role in children with DD insofar as  failures in this system may undermine the acquisition of symbolic representations of number. Although some researchers believe DD is a monolithic learning disability that is genetic and neurobiological in origin, the empirical support for various hypotheses suggests that DD may be shaped by heterogeneous characteristics and underlying causes. The present thesis, and the studies presented therein, provides support for the notion that DD is indeed heterogeneous. We identify at least two subtypes of DD that are characterized by specific deficits in number processing, and one subtype that could more aptly be labelled as a mathematical learning disability, the causal factors of which are likely limited to deficits in non-numerical abilities. In addition, we locate candidate neurocognitive correlates that may be dysfunctional in DD.

Abstract [sv]

Dyskalkyli är en specifik inlärningssvårighet som karaktäriseras av stora svårigheter med att tillgodogöra sig matematikkunskaper som inte kan härledas till bristande undervisningsmöjligheter, språkfärdigheter, eller motivation. Prevalensen av dyskalkyli uppskattas till 3-6%, vilket innebär att en ansenlig andel av populationen har sådana besvär att lära sig matematik att det påverkar deras allmänna välbefinnande och akademiska möjligheter. Förståelsen för dyskalkyli är emellertid knapphändig, men ett flertal konkurrerande hypoteser har föreslagits avseende dess karaktäristika och kausala faktorer. Syftet med denna avhandling är att öka vår förståelse av dyskalkyli utifrån ett kognitionspsykologiskt perspektiv och utifrån kognitiv neurovetenskap. Följaktligen identifierade vi skolbarn med specifika och stora matematiksvårigheter för att sedermera undersöka vilka kognitiva faktorer som underminerar deras förmåga att förvärva grundläggande matematikfärdigheter. Rådande uppfattning är att människan är utrustad med en medfödd förmåga att uppfatta och representera antal, vilket är en förmåga som vi fylogenetiskt delar med andra arter. Vi undersöker huruvida detta medfödda antalsuppfattningssystem är involverat vid utvecklandet av dyskalkyli hos barn, där ett dysfunktionellt antalsuppfattningssystem kan underminera förmågan att tillgodogöra sig symboliska representationer av antal. Gängse uppfattning gör gällande att dyskalkyli är en enhetlig och homogen inlärningssvårighet som genetiskt och neurobiologiskt betingad. Dock har ett flertal hypoteser angående orsaken till dyskalkyli fått empiriskt stöd, vilket möjliggör tolkningen att dyskalkyli snarare är en heterogen inlärningssvårighet med olika kausala faktorer och egenskaper. Föreliggande avhandling ger stöd för denna senare tolkning. Vi identifierar åtminstone två  subtyper av dyskalkyli, som vardera karaktäriseras av specifika svårigheter med numeriska färdigheter, samt en subtyp som mer korrekt bör benämnas som matematiska inlärningssvårigheter där bidragande faktorer sannolikt kan härledas till icke-numeriska förmågor. Vidare så identifierar vi potentiella neurokognitiva korrelat som är dysfunktionella vid dyskalkyli.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2016. , 94 p.
Series
Linköping Studies in Arts and Science, ISSN 0282-9800 ; 669Linköping Studies in Behavioural Science, ISSN 1654-2029 ; 195
Keyword [en]
Developmental Dyscalculia, mathematical learning disabilities, number sense
Keyword [sv]
Dyskalkyli, matematiksvårigheter, antalsuppfattning
National Category
Psychology Neurosciences
Identifiers
URN: urn:nbn:se:liu:diva-124669DOI: 10.3384/diss.diva-124669ISBN: 978-91-7685-831-8 (print)OAI: oai:DiVA.org:liu-124669DiVA: diva2:901938
Public defence
2016-03-11, Key 1, Hus Key, Campus Valla, Linköping, 10:00 (Swedish)
Opponent
Supervisors
Available from: 2016-02-09 Created: 2016-02-09 Last updated: 2016-02-11Bibliographically approved
List of papers
1. Development of magnitude processing in children with developmental dyscalculia: space, time, and number
Open this publication in new window or tab >>Development of magnitude processing in children with developmental dyscalculia: space, time, and number
2014 (English)In: Frontiers in Psychology, ISSN 1664-1078, E-ISSN 1664-1078, Vol. 5, 675Article in journal (Refereed) Published
Abstract [en]

Developmental dyscalculia (DD) is a learning disorder associated with impairments in a preverbal non-symbolic approximate number system (ANS) pertaining to areas in and around the intraparietal sulcus (IPS). The current study sought to enhance our understanding of the developmental trajectory of the ANS and symbolic number processing skills, thereby getting insight into whether a deficit in the ANS precedes or is preceded by impaired symbolic and exact number processing. Recent work has also suggested that humans are endowed with a shared magnitude system (beyond the number domain) in the brain. We therefore investigated whether children with DD demonstrated a general magnitude deficit, stemming from the proposed magnitude system, rather than a specific one limited to numerical quantity. Fourth graders with DD were compared to age-matched controls and a group of ability-matched second graders, on a range of magnitude processing tasks pertaining to space, time, and number. Children with DD displayed difficulties across all magnitude dimensions compared to age-matched peers and showed impaired ANS acuity compared to the younger, ability-matched control group, while exhibiting intact symbolic number processing. We conclude that (1) children with DD suffer from a general magnitude processing deficit, (2) a shared magnitude system likely exists, and (3) a symbolic number-processing deficit in DD tends to be preceded by an ANS deficit.

Place, publisher, year, edition, pages
Frontiers Research Foundation, 2014
Keyword
developmental dyscalculia; number processing; approximate number system; ATOM; time estimation; development
National Category
Psychology
Identifiers
urn:nbn:se:liu:diva-109259 (URN)10.3389/fpsyg.2014.00675 (DOI)000338727700001 ()25018746 (PubMedID)
Available from: 2014-08-12 Created: 2014-08-11 Last updated: 2017-12-05Bibliographically approved
2. Number Processing and Heterogeneity of Developmental Dyscalculia: Subtypes With Different Cognitive Profiles and Deficits
Open this publication in new window or tab >>Number Processing and Heterogeneity of Developmental Dyscalculia: Subtypes With Different Cognitive Profiles and Deficits
2016 (English)In: Journal of Learning Disabilities, ISSN 0022-2194, E-ISSN 1538-4780, Vol. 49, no 1, 36-50 p.Article in journal (Refereed) Published
Abstract [en]

This study investigated if developmental dyscalculia (DD) in children with different profiles of mathematical deficits has the same or different cognitive origins. The defective approximate number system hypothesis and the access deficit hypothesis were tested using two different groups of children with DD (11-13 years old): a group with arithmetic fact dyscalculia (AFD) and a group with general dyscalculia (GD). Several different aspects of number magnitude processing were assessed in these two groups and compared with age-matched typically achieving children. The GD group displayed weaknesses with both symbolic and nonsymbolic number processing, whereas the AFD group displayed problems only with symbolic number processing. These findings provide evidence that the origins of DD in children with different profiles of mathematical problems diverge. Children with GD have impairment in the innate approximate number system, whereas children with AFD suffer from an access deficit. These findings have implications for researchers selection procedures when studying dyscalculia, and also for practitioners in the educational setting.

Place, publisher, year, edition, pages
SAGE PUBLICATIONS INC, 2016
Keyword
developmental dyscalculia; symbolic number processing; nonsymbolic number processing; calculation; arithmetic fact retrieval
National Category
Basic Medicine
Identifiers
urn:nbn:se:liu:diva-124120 (URN)10.1177/0022219414522707 (DOI)000365760200003 ()24598147 (PubMedID)
Note

Funding Agencies|Swedish Research Council [421-2007-1881]

Available from: 2016-01-22 Created: 2016-01-19 Last updated: 2017-11-30
3. Heterogeneity of developmental dyscalculia: Cases with different deficit profiles
Open this publication in new window or tab >>Heterogeneity of developmental dyscalculia: Cases with different deficit profiles
2017 (English)In: Frontiers in Psychology, ISSN 1664-1078, E-ISSN 1664-1078Article in journal (Refereed) Published
Abstract [en]

Context: The aim was to further understand the heterogeneity of  developmental dyscalculia (DD). Utilizing four children (8-9 year-old) performance was contrasted against predominant hypotheses of DD.

Case report: Despite showing similar mathematical deficits, these children showed remarkable interindividual variability regarding cognitive profile and deficits. Two cases were consistent with the approximate number system deficit account, and the general magnitude-processing deficit account. One case had an access deficit in combination with a general cognitive deficit. One cases suffered from general cognitive deficits only.

Conclusions: The results showed that DD cannot be attributed to a single explanatory factor. These findings support a multiple deficits account of DD and suggest that some cases have multiple deficits, whereas other cases have a single deficit. We discuss a previously proposed distinction between primary DD and secondary DD, and suggest hypotheses of dysfunctional neurocognitive correlates responsible for the displayed deficits.

Place, publisher, year, edition, pages
Frontiers Media, 2017
Keyword
Developmental dyscalculia, symbolic number processing, non-symbolic number processing, time processing, spatial processing
National Category
Psychology
Identifiers
urn:nbn:se:liu:diva-124666 (URN)10.3389/fpsyg.2016.02000 (DOI)000391102400001 ()
Note

Funding agencies: Swedish Research Council for Health, Working Life and Welfare [2008-0238, 2010-0078]

Available from: 2016-02-09 Created: 2016-02-09 Last updated: 2017-11-30Bibliographically approved
4. Magnitude processing in the brain: an fMRI study of time, space, and numerosity as a shared cortical system
Open this publication in new window or tab >>Magnitude processing in the brain: an fMRI study of time, space, and numerosity as a shared cortical system
2016 (English)In: Frontiers in Human Neuroscience, ISSN 1662-5161, E-ISSN 1662-5161, Vol. 10, no 500Article in journal (Refereed) Published
Abstract [en]

Continuous dimensions, such as time, space, and numerosity, have been suggested to be subserved by common neurocognitive mechanisms. Neuroimaging studies that have investigated either one or two dimensions simultaneously have consistently identified neural correlates in the parietal cortex of the brain. However, the degree of neural overlap across several dimensions has yet to be established, and it remains an open question whether a potential overlap can be conceptualized as a neurocognitive magnitude processing system. The current functional resonance imaging (fMRI) study investigated the potential neurocognitive overlap across three dimensions. A sample of adults (N = 24) performed three different magnitude processing tasks: a temporal discrimination task, a number discrimination task, and a line length discrimination task. A conjunction analysis revealed several overlapping neural substrates across multiple magnitude dimensions, and we argue that these cortical nodes comprise a distributed magnitude processing system. Key components of this predominantly right-lateralized system include the intraparietal sulcus, insula, premotor cortex, inferior frontal gyrus and frontal eye-fields. Together with previous research highlighting IPS, our results suggest that the insula also is a core component of the magnitude processing system. We discuss the functional role of each of these components in the magnitude processing system and suggest that further research of this system may provide insight into the etiology of neurodevelopmental disorders where cognitive deficits in magnitude processing are manifest.

Place, publisher, year, edition, pages
Frontiers Media, 2016
Keyword
Number processing, Time processing, Spatial processing, Magnitude processing, Insula, Intraparietal sulcus (IPS)
National Category
Psychology Social Sciences Interdisciplinary
Identifiers
urn:nbn:se:liu:diva-124667 (URN)10.3389/fnhum.2016.00500 (DOI)000385888600001 ()27761110 (PubMedID)
Note

Funding Agencies|Swedish Council for Working Life and Social Research [2010-0078]

Available from: 2016-02-09 Created: 2016-02-09 Last updated: 2017-11-30Bibliographically approved

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