Math Is Fun Forum

Jai Ganesh

Administrator

Registered: 2005-06-28

Posts: 48,414

Acalculia and Dyscalculia

Acalculia (not to be confused with dyscalculia), from the Greek "a" meaning "not" and Latin "calculare", which means "to count", is an acquired impairment in which patients have difficulty performing simple mathematical tasks, such as adding, subtracting, multiplying and even simply stating which of two numbers is larger. Acalculia is distinguished from dyscalculia in that acalculia is acquired late in life due to neurological injury such as stroke, while dyscalculia is a specific developmental disorder first observed during the acquisition of mathematical knowledge. This condition is associated with lesions of the parietal lobe (especially the angular gyrus) and the frontal lobe and can be an early sign of dementia. Acalculia is sometimes observed as a "pure" deficit, but is commonly observed as one of a constellation of symptoms, including agraphia, finger agnosia and left-right confusion, after damage to the left angular gyrus, knowns as Gerstmann's syndrome (Gerstmann, 1940; Mayer et al., 1999).

Studies of patients with lesions to the parietal lobe have demonstrated that lesions to the angular gyrus tend to lead to greater impairments in memorized mathematical facts, such as multiplication tables, with relatively unimpaired subtraction abilities. Conversely, patients with lesions in the region of the intraparietal sulcus tend to have greater deficits in subtraction, with preserved mulitiplication abilities (Dehaene and Cohen, 1997). These double dissociations lend support to the idea that different regions of the parietal cortex are involved in different aspects of numerical processing.

Dyscalculia (difficulty in learning or comprehending mathematics) was originally identified in case studies of patients who suffered specific arithmetic disabilities as a result of damage to specific regions of the brain. Recent research suggests that dyscalculia can also occur developmentally, as a genetically-linked learning disability which affects a person's ability to understand, remember, and/or manipulate numbers and/or number facts (e.g. the multiplication tables). The term is often used to refer specifically to the inability to perform arithmetic operations, but is defined by some educational professionals and cognitive psychologists as a more fundamental inability to conceptualize numbers as abstract concepts of comparative quantities (a deficit in "number sense"). Those who argue for this more constrained definition of dyscalculia sometimes prefer to use the technical term Arithmetic Difficulties (AD) to refer to calculation and number memory deficits.

Dyscalculia is a lesser known disability, similar and potentially related to dyslexia and dyspraxia. Dyscalculia occurs in people across the whole IQ range, and sufferers often, but not always, also have difficulties with time, measurement, and spatial reasoning. Current estimates suggest it may affect about 5% of the population. Although some researchers believe that dyscalculia necessarily implies mathematical reasoning difficulties as well as difficulties with arithmetic operations, there is evidence (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.

The word 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". That word "calculare" again comes from "calculus", which means "pebble" or one of the counters on an abacus.

Dyscalculia can be detected at a young age and measures can be taken to ease the problems faced by younger students. The main problem is understanding the way mathematics is taught to children. In the way that dyslexia can be dealt with by using a slightly different approach to teaching, so can dyscalculia. However, dyscalculia is the lesser known of these learning disorders and so is often not recognized.

Another common manifestation of the condition emerges when the individual is faced with equation type of problems which contain both integers and letters (3A + 4C). It can be difficult for the person to differentiate between the integers and the letters. Confusion such as reading a '5' for an 'S' or not being able to distinguish between a zero '0' for the letter 'O' can keep algebra from being mastered. This particular form of dyscalculia is often not diagnosed until middle or high school is entered.

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It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

JohnnyReinB

Member

Registered: 2007-10-08

Posts: 453

Re: Acalculia and Dyscalculia

I seem to remember reading some disorder lie that in Discovery.

It seems unfortunate for some that they might never discover the beauty of numbers, don't you think?

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"There is not a difference between an in-law and an outlaw, except maybe that an outlaw is wanted"

Nisi Quam Primum, Nequequam

John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: Acalculia and Dyscalculia

Very interesting ganesh.
I am working to improve my addition and subtraction by getting better at counting up and down.
Like if I think of two single digit numbers, say 3 and 7, then
I see how long it takes me to find the numbers in between, like 4 5 6.
Being that I am weird, I spend a lot of time trying to get faster at this, though most people would be immediately turned off from the increadible boredom of such a remedial task.
Like take 9 and 2, 1 and 0 are between them the short way.
But pairs 3&8 4&7 5&6 are the long way from 2 to 9.
Some people like complicated things; I like easy things.

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