title: Manual actions cover symbolic distances at different speed.
abstract: A privileged way of representing numbers in the human mind is along an oriented mental number line. Activation of this representation has been proposed to account for the impact of numbers on motor tasks, such as on grasping, pointing, and eye movements. Here we evaluated the impact of numbers on motor control, by exploiting the evidence that the speed reached by the manual connection of two points is correlated with their physical distance. We reasoned that, if irrelevant numbers induce a mis-perception of the distance between two points, this should be reflected in the movement speed. Results showed a speed difference in the manual connection of two numerically close numbers (i.e., connected slower) and two numerically distant numbers (i.e., connected faster), placed at equal physical distance. This representational length effect indicates not only that symbolic distance modulates speed movement as physical distance does, but suggests that the impact of numbers on action planning does not only involve action initiation but it extends to the definition of kinematic parameters. More generally, the reported findings show that the representation of numbers along a mental space affects our behaviour in the physical space.
authors.affiliation: Department of Psychology, University of Milano-Bicocca, Milano, Italy; NeuroMI, Milan Center for Neuroscience, Milano, Italy. Electronic address: luisa.girelli@unimib.it.
authors.forename: Luisa
authors.initials: L
authors.lastname: Girelli
authors.affiliation: Department of Psychology, University of Milano-Bicocca, Milano, Italy.
authors.forename: Gelsomina
authors.initials: G
authors.lastname: Perrone
authors.affiliation: Laboratoire des Fluides Complexes et leurs Réservoirs - UMR5150, Université de Pau et des Pays de l'Adour, 64600 Anglet, France.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Croccolo
authors.affiliation: Division of ITCE, Pohang University of Science and Technology, Gyungbuk, South Korea.
authors.forename: Eduardo H
authors.initials: EH
authors.lastname: Roman
authors.affiliation: Department of Psychology, University of Milano-Bicocca, Milano, Italy; NeuroMI, Milan Center for Neuroscience, Milano, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Bricolo
authors.affiliation: Department of Physics "G.Occhialini" and PLASMAPROMETEO, University of Milano-Bicocca, Milano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Mancin
authors.affiliation: Department of Psychology, University of Milano-Bicocca, Milano, Italy; NeuroMI, Milan Center for Neuroscience, Milano, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Rinaldi
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D004215:Distance Perception; D005133:Eye Movements; D005260:Female; D006801:Humans; D008297:Male; D009949:Orientation; D011597:Psychomotor Performance; D011930:Reaction Time; D013028:Space Perception; D013223:Statistics as Topic; D013561:Symbolism; D055815:Young Adult
keywords: Action planning; Kinematic parameters; Mental number line; Spatial representation; Symbolic distance