Ranzini, M. 1 , Anelli, F. 1 , Borghi, A. M. 1, 2 , Carbone, R. 1 , Lugli, L. 1 & Nicoletti, R. 1
1 University of Bologna, Bologna, Italy
2 Institute of Cognitive Science and Technology - CNR, Roma, Italy
Several studies have described common processing between numerical and physical magnitudes, and between number and action. However, they did not control for object graspability (affordance). This study investigates the relationship between numerical magnitude, object size, and affordances in two experiments, without (Experiment 1) or with (Experiment 2) motor involvement (i.e. participants had to hold/grasp an object during the task). The task consisted in repeating aloud the odd or even digit within a pair depending on the type of the preceding or following object. Numerical magnitude (small vs. large), object size (small vs. large), object type (graspable vs. ungraspable), and order (object-number vs. number-object) were manipulated for each experiment. Experiment 1 showed a facilitation for graspable over ungraspable objects preceded by the numbers presentation, and a numerical magnitude effect after graspable objects presentation. Thus, graspability was more relevant than size for number processing. Experiment 2 demonstrated that motor involvement interfered with graspability, however enhancing the sensibility to both numerical and object size. Overall, these findings demonstrate that not only object size, but also object affordances, which involve the motor system, affect number processing. Crucially, they suggest that abstract and concrete concepts are linked through perception-action systems.