Ludovica Veggiotti, Gisella Decarli, Maria Dolores de Hevia Université de Paris, INCC UMR 8002, CNRS, F-75006 Paris, France
Humans’ inborn ability to discriminate, represent, and manipulate numerical quantities’ is supported by the parietal cortex, which is also involved in a variety of spatial and motor abilities. While the behavioral links between numerical and spatial information have been extensively studied, little is known about the behavioral connection between number and action. Some studies in adults have shown a series of interference effects when simultaneously processing numerical and action information. We investigated the origins of this link in human infants (7-9 m.o.) using an habituation paradigm. Forty infants were tested in one of two experimental conditions: one group was habituated to congruent number-hand pairings, where the larger the number, the more open the hand-shape associated; the second group was habituated to incongruent number-hand pairings, where the larger the number, the more close the hand-shape associated. In test trials, both groups of infants were presented with one instance of a congruent and one instance of an incongruent pairing (using new combinations of numbers and hand-shapes). We found a significant Habituation conditionxTest trial interaction, as only infants habituated to a congruent number-hand pairing showed a significantly higher looking time to the test trial depicting an incongruent pairing; in contrast, infants habituated to an incongruent pairing did not show any looking time difference between test trials. These findings show that infants spontaneously associate magnitude-related changes across the dimensions of number and action-related information, offering thus support to the existence of an early, preverbal number-action link in the human mind.
