Dyscalculia
Classification and external resources
Lateral surface of left cerebral hemisphere, viewed from the side. (Intraparietal sulcus visible at upper right, running horizontally.)
ICD-10	F81.2, R48.8
ICD-9	315.1, 784.69

Dyscalculia (or maths disability) is a specific learning disability involving innate difficulty in learning or comprehending arithmetic. It is akin to dyslexia and includes difficulty in understanding numbers, learning how to manipulate numbers, learning maths facts, and a number of other related symptoms (although there is no exact form of the disability). Maths disabilities can also occur as the result of some types of brain injury, in which case the proper term is acalculia, to distinguish it from dyscalculia which is of innate, genetic or developmental origin.

Although maths learning difficulties occur in children with low IQ^[1] dyscalculia occurs in people across the whole IQ range, and sufferers often, but not always, also have difficulties with time, measurement, and spatial reasoning.^[2][3] Estimates of the prevalence of dyscalculia range between 3 and 6% of the population.^[2][3] Dyscalculia does not necessarily imply higher mathematical reasoning difficulties as well as difficulties with arithmetic operations; in fact, evidence exists (especially from brain damaged patients) that arithmetic (e.g. calculation and number fact memory) and mathematical (abstract reasoning with numbers) abilities can be dissociated. That is (some researchers argue), an individual might suffer arithmetic difficulties (or dyscalculia), with no impairment of, or even giftedness in, abstract mathematical reasoning abilities.

History[link]

The term dates back to at least 1949.^[4][5]

Mental disabilities specific to maths were originally identified in case studies with patients who suffered specific arithmetic disabilities as a result of damage to specific regions of the brain. More commonly, dyscalculia occurs developmentally, as a genetically linked learning disability which affects a person's ability to understand, remember, or manipulate numbers or number facts (e.g., the multiplication tables). The term is often used to refer specifically to the inability to perform arithmetic operations, but it is also defined by some educational professionals and cognitive psychologists such as Stanislas Dehaene^[6] and Brian Butterworth^[3] as a more fundamental inability to conceptualize numbers as abstract concepts of comparative quantities (a deficit in "number sense"), which these researchers consider to be a foundational skill, upon which other maths abilities build.^[2][3]

Etymology[link]

Dyscalculia comes from Greek and Latin which means: "counting badly". The prefix "dys" comes from Greek and means "badly". "Calculia" comes from the Latin "calculare," which means "to count". The word "calculare" comes from "calculus" (the diminutive of "calx," which means stone), which means "pebble" or one of the counters on an abacus.

Synonym - Numlexia^{[dubious – discuss][citation needed]}

Symptoms[link]

The earliest symptom of dyscalculia to appear is a deficit in subitizing. Subitizing is the ability to know, from a brief glance and without counting, how many objects there are in a small group. This is an innate ability, present in human infants from birth. Homologous circuits exist in primates, and many other animals have been shown to possess similar ability; obviously, there is survival value in knowing how many predators there are, etc. Human infants can typically subitize three objects, and this number grows as the person matures, so that most adults can subitize 5 or more objects. However, children with dyscalculia can subitize fewer objects and even when correct take longer to identify the number than their age-matched peers.^[7] Other symptoms include difficulty reading analog clocks,^[8] and in extreme cases inability to even simply state which of two numbers is larger.

• Frequent difficulties with arithmetic
• Difficulty with everyday tasks like reading analog clocks
• Inability to comprehend financial planning or budgeting, sometimes even at a basic level; for example, estimating the cost of the items in a shopping basket or balancing a checkbook
• Difficulty with multiplication-tables, and subtraction-tables, addition tables, division tables, mental arithmetic, etc.
• Difficulty with conceptualizing time and judging the passing of time. May be chronically late or early
• Particularly problems with differentiating between left and right
• Inability to visualize mentally
• Difficulty reading musical notation
• Might do exceptionally well in a writing-related field — authors and journalists are more likely than average to have the disorder^{[dubious – discuss][citation needed]}
• Difficulty navigating or mentally "turning" the map to face the current direction rather than the common North=Top usage
• Having particular difficulty mentally estimating the measurement of an object or distance (e.g., whether something is 10 or 20 feet (3 or 6 meters) away).
• Often unable to grasp and remember mathematical concepts, rules, formulae, and sequences
• Inability to concentrate on mentally intensive tasks
• Low latent inhibition, i.e., over-sensitivity to noise, smell, light and the inability to tune out, filtering unwanted information or impressions. Might have a well-developed sense of imagination due to this (possibly as cognitive compensation to mathematical-numeric deficits)
• Mistaken recollection of names. Poor name/face retrieval. May substitute names beginning with same letter.

^[9]

Causes[link]

Scientists have yet to understand the causes of dyscalculia. They have been investigating in several domains.

• Neurological: Dyscalculia has been associated with lesions to the supramarginal and angular gyri at the junction between the temporal and parietal lobes of the cerebral cortex.^[10][11]

• Deficits in working memory: Adams and Hitch argue that working memory is a major factor in mental addition.^[12] From this base, Geary conducted a study that suggested there was a working memory deficit for those who suffered from dyscalculia.^[13] However, working memory problems are confounded with general learning difficulties, thus Geary's findings may not be specific to dyscalculia but rather may reflect a greater learning deficit.

Other causes may be:

• Short term memory being disturbed or reduced, making it difficult to remember calculations.
• Congenital or hereditary disorders. Studies show indications of this,^[14] but the evidence is not yet concrete.

Gerstmann syndrome: dyscalculia is one of a constellation of symptoms acquired after damage to the angular gyrus.

Involvement of the intraparietal sulcus has been suggested.^[15]

Treatment[link]

Some people with dyscalculia have advocated a shift in attitudes that it is a difference, rather than a disability that must be treated or cured if they show talent in other areas - such as art skills.^{[citation needed]}

Software intended to remediate dyscalculia has been developed.^[16]

Forms of educational therapy, such as neuro-sensory educational therapy, can be an effective treatment.

A study published in Current Biology to "investigate the feasibility of using noninvasive stimulation to the parietal lobe during numerical learning to selectively improve numerical abilities" used transcranial direct current stimulation (TDCS) and demonstrated improvement that was still present six months later.^[17]

See also[link]

• Acalculia
• Ageometria
• Approximate number system
• The DSM-IV diagnosis mathematics disorder can be applied to people whose mathematical abilities are well below the expected level for their age.
• Dyslexia
• Dysgraphia
• Numerical cognition
• Number sense

Notes[link]

References[link]

• Abeel, Samantha, 2003. My Thirteenth Winter. Orchard Books. ISBN 0-439-33904-9
• Attwood, Tony, 2002. Dyscalculia in Schools: What It Is and What You Can Do. First and Best in Education Ltd. ISBN 1-86083-614-3
• Butterworth, Brian, 2004. Dyscalculia Guidance: Helping Pupils With Specific Learning Difficulties in Maths. David Fulton Publications. ISBN 0-7087-1152-9
• Chinn, Steve, 2004. The Trouble with Maths: A Practical Guide to Helping Learners with Numeracy Difficulties. RoutledgeFalmer. ISBN 0-415-32498-X
• Henderson, Anne, Came, Fil, and Brough, Mel, 2003, Working with Dyscalculia. Learning Works International Ltd. ISBN 0-9531055-2-0
• Sharma, Mahesh. Dyscalculia
• Sharma, Mahesh and Loveless, Eugene, 1988. Dyscalculia. Focus on Learning Problems in Mathematics, CT/LM.
• Sharma, Mahesh, 1989. Dyslexia, Dyscalculia and other Mathematics Problems. The Math Notebook, CT/LM.
• Sharma, Mahesh. Berkshire mathematics
• Campbell, Jamie I.D.,2004. "Handbook of Mathematical Cognition". Psychology Press.

External links[link]

• Dyscalculia at the Open Directory Project
• The Dyscalculia Forum - International nonprofit support forum
• Dyscalculia Testing for Children - General testing and treatment