Dyscalculia (or math disability) is a specific learning disability involving innate difficulty in learning or comprehending simple mathematics. It is akin to dyslexia and includes difficulty in understanding numbers, learning how to manipulate numbers, learning math facts, and a number of other related symptoms (although there is no exact form of the disability). Math 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.
Lateral surface of left cerebral hemisphere, viewed from the side. (Intraparietal sulcus visible at upper right, running horizontally.)
Although math learning difficulties occur in children with low IQ dyscalculia can also be found in people with normal to superior intelligence. Estimates of the prevalence of dyscalculia range between 3 and 6% of the population.
History
The term dates back to at least 1974.
Mental disabilities specific to math 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 and Brian Butterworth 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 math abilities build.
Etymology
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”, which means “pebble” or one of the counters on an abacus.
Symptoms
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.
Causes
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.
- Deficits in working memory: Adams and Hitch argue that working memory is a major factor in mental addition. From this base, Geary conducted a study that suggested there was a working memory deficit for those who suffered from dyscalculia. 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, 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.
Treatment
Some people with Dyscalculia have advocated a shift in attitudes toward the view 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.
Software intended to remediate dyscalculia has been developed.
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.