THE ROUGH GUIDE TO PSYCHOLOGY
The psychologist Maggie Snowling at the University of York is
one of the world’s leading authorities on dyslexia. In 2008, she reaf-
firmed that the most effective interventions for dyslexia target readers’
difficulties with phonemes, including providing training in letter
knowledge and how to make links between letters and sounds.
Less well known than dyslexia is dyscalculia – from the Greek
to “count badly”. Children with this diagnosis have mathematical
skills that are far weaker than you’d expect based on their overall
intelligence. They display problems with both arithmetical processing
and arithmetic facts, such as learning multiplication tables. In severe
cases, such children find even basic numerical challenges difficult, such
as being able to say whether the answer to 3 + 4 is in the region of 30 to 40.
Dyscalculia often coincides with other learning problems, including
ADHD (see p.320) and, in about forty percent of cases, dyslexia. Psycholo-
gists have attempted to find out whether these other conditions are
the root cause of the number difficulties, but the results are extremely
inconsistent. Babies and even some animals show basic numerical skills
in terms of distinguishing between quantities, which points to there
being a core numerical system in the brain. Increasingly, the consensus
view is that dyscalculia probably reflects a problem with this core system.
Supporting this idea, research has shown that children with dyscalculia
lack a fundamental numerical ability known as subitising – this is the
ability to glance at a group of items of four or less and know in an instant,
without counting, how many items there are. Children with dyscalculia
will often resort to counting to three or four instead of being able to
recognize these quantities on sight.
Recently, psychologists have turned their attention to finding where
in the brain the core number-system resides. The intra-parietal sulcus,
towards the back of the head, is a prime candidate. For example, a 2007
study found that the application of transcranial magnetic stimulation
to this area – a technique that involves placing a magnet near the skull,
thereby temporarily affecting neuronal activity underneath – disrupted
people’s performance in a task that depended on their sense of numerical
magnitude. What’s more, brain-imaging studies have found that children
with dyscalculia have abnormal functioning in this same neural region.
nextflipdebug5
(nextflipdebug5)
#1