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 Cognition2， German researchers Andrea Bender and Sieghard Belier argue that the extent of cultural diversity3 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 （算術(shù)）.
　　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 recruited4 to represent our concept of number， and that these days it performs both functions.
　　FMRI （Functional Magnetic Resonance Imaging） 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.
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