Put down your coffee for a moment. Now, without thinking about it too much, use your hands to count to 10.
How did you do it? Did you start with the left hand, or the right? Did you begin counting on a thumb, or with a pinkie? Maybe you started on an index finger? And did you begin with a closed fist, or an open hand?
If you're European, there's a good chance you started with closed fists, and began counting on the thumb of the left hand. If you're from the Middle East, you probably also started with a closed fist, but began counting with the little finger of the right hand.
Most Chinese people, and many North Americans, also use the closed-fist system, but begin counting on an index finger, rather than the thumb. The Japanese typically start from an open-hand position, counting by closing first the little finger, and then the remaining digits.
In India, it's common to make use of finger segments to get as many as 20 counts from each hand. It's even been reported that the Amazonian Pirah people don't use their fingers to count at all.
Finger counting feels as natural as breathing – but it's not innate, or even, apparently, universal. There are actually many different techniques, and they are culturally transmitted.
In the latest issue of Cognition, German researchers Andrea Bender and Sieghard Beller argue that the extent of cultural diversity in finger-counting has been hugely underestimated. They also say that by studying finger counting techniques, we could better understand how culture influences cognitive processes – particularly mental arithmetic.
There is a mental link between hands and numbers, but that link doesn't come from humans learning to use their hands as a counting aid. It goes back much further in our evolution. Marcie Penner-Wilger and Michael L. Anderson propose that the part of our brain that originally evolved to represent our fingers has been recruited to represent our concept of number, and that these days it performs both functions.
fMRI scans show that brain regions associated with finger sense are activated when we perform numerical tasks, even if we don't use our fingers to help us complete those tasks. And studies show that young children with good finger awareness are better at performing quantitative tasks than those with less finger sense.
Even as adults, the way we mentally picture numbers in space – the SNARC effect – is related to the hand on which we begin finger counting.
We also know, from studies of German sign language, that the type of finger counting system that we use affects how we mentally represent and process numbers. That may be because finger counting has one unique property that sets it apart from written or verbal counting systems: it is a sensory-motor experience, with a direct link between bodily movement and brain activity.
So, knowing that there is a link between hands and numbers, and that how we process numbers mentally is influenced by how we finger-count, what are the implications of the vast cultural diversity in techniques? Does it mean that we think about numbers differently, depending on our cultural background?
It's possible. Take the Eurasian systems. They're quite literal: one finger equals one count, and the brain immediately perceives this concept. But Chinese finger counting uses symbolic gestures to represent any number higher than five, and people from Papua New Guinea utilise much of the upper body to represent number. Such symbolic gestures need to be learned, and then retrieved as needed from our working memory. That requires more cognitive effort, but symbolic systems do allow for more sophisticated arithmetic.
These questions of diversity lead us into the peculiar world of embodied cognition – the somewhat controversial theory that body parts other than the brain can play a role in cognition. Proponents of embodied cognition argue that we reduce the cognitive load on the brain by outsourcing tasks to other parts of our body, and in the related case of distributed cognition, even to external objects.
The cultural diversity of finger counting may lead to new insights into embodied cognition. Does the neurological feedback from these different types of body-based counting influence how we think about numbers? This is fascinating, but those of us who are not naturally good at maths might reasonably ask a more simple question.
Could it be that some people are always going to be better at maths than others, just because of where they grew up?
That's unlikely, says Dr Bender, who points out that some aspects of finger counting are widespread across the world, while others vary even within a given culture. She does, though, believe that by practising different techniques of finger counting we could all improve our mental arithmetic. That hasn't been empirically tested yet, but it might be worth a try.
Burns, Corrinne. 2012. "What does the way you count on your fingers say about your brain?". The Guardian. Posted: June 26, 2012. Available online: http://www.guardian.co.uk/science/blog/2012/jun/26/count-fingers-brain