Abridged extract from “Attention, balance and coordination – the A,B,C of learning success” by Sally Goddard Blythe, of INPP. Due to be published by Wiley-Blackwell Professional. Autumn 2008.
Dys means difficulty and calculia is derived from the Latin word for calculus meaning small stone. In the original context it refers to the ancient use of pebbles used for counting which later developed into the abacus. This earlier use of stones as “mind tools” or concrete representations of concepts, suggests that physical interaction has been used as an aid to support and precede conceptual understanding of numbers for generations.
Dyscalculia describes developmental lag of 1 year or more in the acquisition of numerical skills, including:
Dyscalculia is more prevalent in children of lower socio-economic status. Unlike Dyslexia it is equally distributed between the sexes and there is an association between premature birth and later difficulties with number skills. Badian (1983)i proposed 3 types of dyscalculia:
Dysfunction in either hemisphere can impair acquisition of numerical skills but appear to be more profound if present in the left hemisphere. Left hemisphere dysfunction has been found to be associated with construction dyspraxia and below average performance on tasks such as The Embedded Figures Testi (figure ground effect), poor auditory and visual discrimination and motor coordination abilities.
Right hemisphere dysfunction in a group of children who showed no signs of structural abnormality on brain scans (MRI or CT) manifested itself as grapho-motor impairments and slow cognitive and motor performance, although reading development was normali. Additional right hemisphere symptoms included: emotional and inter-personal difficulties, difficulty adapting to new situations, difficulty maintaining friendships, tendency to be withdrawn and shy, poor eye contact and difficulties with spatial perception and imagery. Some of this group also had features of ADHD which it was suggested might be a secondary effect of right hemisphere dysfunction and brain stem factors. Many of these symptoms associated with right hemisphere dysfunction can also occur as a result of dysfunction in the vestibular system and associated pathways, which support the processes of visual perception in the right hemisphere.
Risey and Briner (1990) found a relationship between patients with central vertigo and Dyscalculia, which affected their ability to perform certain tasks counting backwards accurately. Patients with vertigo, which is indicative of faulty vestibular functioning, consistently made the same error each time they were asked to perform the task. They recognised the mistake when it was pointed out to them, but could not avoid repeating the same error, each time they were asked to perform the task. They also had difficulties with mental arithmetic and central auditory processing, lower scores for arithmetic and digit span errors on the Wechsler Adult Intelligence Scale (WAIS) and difficulty with backward digit span recall compared to non vertigo patients, suggesting that vestibular dysfunction can affect visual, auditory and mental sequencing processes.