Martin Fischer, University of Dundee, Scotland, recently reported results showing that the majority of adults prefer to start counting on their left hand, regardless of whether they are left- or right-handed. In a subsequent odd-even task, the left-starters had more consistent spatial-numerical associations than the right-starters.

Simple numerical tasks, such as classifying digits as odd or even by pressing left or right buttons reveal that we like to associate small numbers with left space. Where does this preference come from?

The link between finger counting habits and numerical cognition may have implications for mathematics teaching and even the rehabilitation of people who have lost their number sense.

Fischer's study explored the contribution of finger counting habits to the association of numbers with space (the SNARC effect).

First, a questionnaire study indicated that two-thirds of 445 adults started counting on their left hand, regardless of their handedness. Secondly, a group of 53 ‘‘left-starters’’ but not a group of 47 ‘‘right-starters’’ showed a SNARC effect in a parity task.

This significant difference in the strength of the effect between groups suggests that finger counting habits indeed contribute to the association between numbers and space in adults.

Article: Fischer MH: 'Finger counting habits modulate spatial-numerical associations.' Cortex 2008; 44: 386-392.