As I mentioned
in an earlier post (about Dyscalculia screener), numerosity is the ability to
represent, estimate and manipulate quantities.
This new
article sheds more light on numerosity:
Why do we differ in number sense? Evidence from a genetically
sensitive investigation.
M.G. Tostoa, S.A. Petrill , J. Halberda , M.
Trzaskowski , T.N. Tikhomirova , O.Y. Bogdanova ,R. Ly , J.B. Wilmer , D.Q.
Naiman, L. Germine , R. Plomin, Y. Kovas.
Intelligence 43
(2014) 35–46
Apparently,
numerosity is a developing
ability. Six months old babies
can distinguish between arrays of items of 4 from 8, and 8 from 16 (ratio
1:2). Nine months old babies can
discriminate between displays of 8 and 12 items (ratio 2:3). Three year olds can distinguish between
ratios of 3:4 and six year olds – of 5:6.
Adults can discriminate between arrays with ratios of 9:10 (!). The ability to discriminate between
quantities improves till the age of 30 and then begins to deteriorate.
The article
describes a large scale research about numerosity with 16 year old twins. The twins were presented with arrays of yellow
and blue dots for a very brief time. They
had to decide whether there were more yellow or blue dots. It was
found, that numerosity correlates 0.3 with math achievement, 0.25 with
processing speed, 0.22 with visual spatial working memory, 0.27 with nonverbal
ability and 0.2 with language.
It was also
found, that individual differences
in numerosity among the 16 year olds were only modestly (32%) influenced by
genetic factors. Most of the variance
was explained by environmental effects.
Individual differences
in the ability to distinguish between quantities appear as early as in 6 months
old babies. The authors suggest that in infancy, individual
differences in numerosity are heavily influenced by genes, but in later
development, numerosity is more affected by exposure to math stimuli, interest
in activities with numbers and the amount of practice in math activities. That means that numerosity can be trained and improved. Even in infancy, 6 months old babies that
received quantitative stimuli that were both visual and auditory, were able to
distinguish between quantities with a ratio usually found in 9 months old
babies. It's possible that the multisensory
information the babies received improved numerosity.
It's also
possible, that children born with poor numerosity and/or low general cognitive
ability are less inclined to engage in activities with numbers and thus don't
give their numerosity a chance to develop to its full potential.
That’s why it's
especially important for children with poor numerosity not to give up and be
exposed to math experiences and games. This
will help them train and improve their numerosity.
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