On the relationship between handedness and hand-digit mapping in finger counting.

The purpose of the current investigation was to evaluate hand-digit mapping in finger counting in French children and adults and whether handedness might constraint hand-digit mapping. To this aim, hand-digit mapping used when counting from one to ten by means of fingers, together with performance-based and preference-based measures of handedness, were evaluated in French individuals of four different age groups (4-5 years old, 6-7 years old, 10-11 years old and 24-47 years old). Irrespective of the age group, analyses revealed a strong tendency to use first the right hand to count from one to five and then the left hand to count from six to ten. In addition, a significant interaction between hand-digit mapping and hand preference was found, with participants who used first their right hand to count reporting higher right-hand preference in unimanual activities. These findings are discussed in light of recent studies assuming a link between finger-counting habits and numerical processing.