Nature Science Update
Females faster at spotting small numbers
by Joanne Baker
Nature Science Update: 11th September, 2003.
Women have a better instinct for small numbers than men, hints a new
In a maths test based at a science museum, female volunteers recognized
one to four dots more quickly than males did. Both sexes did equally well
at counting larger numbers of dots.
"This is not what we predicted," says study leader Brian Butterworth of
University College London. "We thought it just got steadily harder to
count more and more objects."
The findings add to evidence that the brain deals differently with small
and large numbers. We seem to have a built-in idea of 'two-ness' or
'three-ness', but must count to distinguish 12 and 13, say. The time
difference between tallying 2 or 3 objects is much smaller than for
differentiating 12 and 13, or 22 and 23.
Researchers hope that understanding the brain's counting mechanisms will
help the 5% of children who have severe difficulty in learning maths.
Butterworth installed his computer test at Britain's @Bristol science
museum. It measured reaction times for 18,000 people aged between 5 and
65. Visitors tapped buttons on a screen to say whether a number of dots
displayed agreed with a figure shown next to it. "We wanted to engage the
public in science by getting them to be part of the experiment itself,"
says exhibition manager Penny Fidler.
It takes about half a second to tot up a few dots. Women beat men by 50
thousandths of a second on average. This advantage disappeared for five or
Museum visitors also counted large numbers more easily with their left
eye. This implies that the right side of the brain, which governs the left
eye, is involved in counting. "The right hemisphere is important for
estimating numbers in a non-verbal way," says Butterworth. The left brain
associates numbers with words - the digit 7 with its title 'seven', say -
and is involved in calculating.
Why the brain treats small and large numbers differently is not clear.
Some social animals - rats, lions and chimpanzees - can count, a skill
that perhaps enables them to decide how their group should react to single
or multiple intruders.
Joanne Baker is a British Association Media Fellow