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Front. Psychol. | doi: 10.3389/fpsyg.2018.00637

Numerical affordance influences action execution: A Kinematic Study of Finger Movement

  • 1Università degli Studi di Padova, Italy

Humans represent symbolic numbers as oriented from left to right: the Mental Number Line (MNL). Up to now, scientific studies have mainly investigated the MNL by means of response times. However, the existing knowledge on the MNL can be advantaged by studies on motor patterns while responding to a number. Cognitive representations, in fact, cannot be fully understood without considering their impact on actions.
Here we investigated whether a motor response can be influenced by number processing. Participants seated in front of a little soccer goal. On each trial they were visually presented with a numerical (2, 5, 8) or a non-numerical ($) stimulus. They were instructed to kick a small ball with their right index toward a frontal soccer goal as soon as a stimulus appeared on a screen. However, they had to refrain from kicking when number five was presented (no-go signal).
Our main finding is that performing a kicking action after observation of the larger digit proved to be more efficient: the trajectory path was shorter and lower on the surface, velocity peak was anticipated. The smaller number, instead, specifically altered the temporal and spatial aspects of trajectories, leading to more prolonged left deviations. This is the first experimental demonstration that the reaching component of a movement is influenced by number magnitude. Since this paradigm does not require any verbal skill and non-symbolic stimuli (array of dots) can be used, it could be fruitfully adopted to evaluate number abilities in children and even preschoolers. Notably, this is a self-motivating and engaging task, which might help children to get involved and to reduce potential arousal connected to institutional paper-and-pencil examinations.

Keywords: mental number line, Spatial-numerical association, kinematics, reaching, action execution, finger movement, Numerical cognition

Received: 13 Dec 2017; Accepted: 16 Apr 2018.

Edited by:

Hans-Christoph Nuerk, Universität Tübingen, Germany

Reviewed by:

Samuel Shaki, Ariel University, Israel
Thomas J. Faulkenberry, Tarleton State University, United States  

Copyright: © 2018 Rugani, Betti and Sartori. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Dr. Rosa Rugani, Università degli Studi di Padova, Padova, Italy, rosa.rugani@unipd.it
Dr. Luisa Sartori, Università degli Studi di Padova, Padova, Italy, luisa.sartori@unipd.it