Numerical representation are influenced by spatial relation or finger counting? An eye tracking study

Background: Fingers are employed to represent numerosities before symbolic representations are used meaning that finger use might be the fundamental basis of numerical knowledge. Fingers are a support during the recitation of the numerical chain and they might also help children to understand the cardinal meaning of number words. Fingers are used to point at each object when counting a set, which is important in establishing the one-to-one correspondence principle. Finally fingers can help to keep track of the counted items in mental calculations which alleviates the burden on working memory and increases accuracy. In our study we attempted to investigate the relationship between the embodiment effect and mathematical and spatial representation (SNARC effect). Methods: we presented to adult subjects (N=35) between 19 and 27 years of age, a coupling fingernumber task that involves three different conditions. Each condition depicted a hands in which the numbers from one to five were placed above each finger in a random condition (random), in a inverted condition (number one on the little finger ending with the number five on the thumb) or in an orderly condition (number one on the thumb ending with the number five on the little finger). Parameter taking into account were: Accuracy; response times; number of fixations; difference in the number of fixations; saccades difference. Results: The orderly and inverted configuration resulted the more efficient in order to elicits a decrease of response time and a decrease of saccades and fixation. The random condition resulted in the poorer performance on all parameter analyzed with the higher response times, higher number of fixations and major saccades difference. Conclusions: We observed a facilitation effect in orderly and inverted condition due, in the orderly condition, to embodied effect, and, in the inverted one, to spatial numerical representation