Act on Numbers: Numerical Magnitude Influences Selection and Kinematics of Finger Movement

Abstract

In the past decade hand kinematics has been reliably adopted for investigating cognitive processes and disentangling debated topics. One of the most controversial issues in numerical cognition literature regards the origin – cultural vs. genetically driven – of the mental number line (MNL), oriented from left (small numbers) to right (large numbers). To date, the majority of studies have investigated this effect by means of response times, whereas studies considering more culturally unbiased measures such as kinematic parameters are rare. Here, we present a new paradigm that combines a “free response” task with the kinematic analysis of movement. Participants were seated in front of two little soccer goals placed on a table, one on the left and one on the right side. They were presented with left- or right-directed arrows and they were instructed to kick a small ball with their right index toward the goal indicated by the arrow. In a few test trials participants were presented also with a small (2) or a large (8) number, and they were allowed to choose the kicking direction. Participants performed more left responses with the small number and more right responses with the large number. The whole kicking movement was segmented in two temporal phases in order to make a hand kinematics’ fine-grained analysis. The Kick Preparation and Kick Finalization phases were selected on the basis of peak trajectory deviation from the virtual midline between the two goals. Results show an effect of both small and large numbers on action execution timing. Participants were faster to finalize the action when responding to small numbers toward the left and to large number toward the right. Here, we provide the first experimental demonstration which highlights how numerical processing affects action execution in a new and not-overlearned context. The employment of this innovative and unbiased paradigm will permit to disentangle the role of nature and culture in shaping the direction of MNL and the role of finger in the acquisition of numerical skills. Last but not least, similar paradigms will allow to determine how cognition can influence action execution.

Peer Review #1 of "Compatibility between object size and response side in grasping: the left hand prefers smaller objects, the right hand prefers larger objects (v0.1)"

“…Although most studies have examined interactions between numerical information and motor-related spatial coding (e.g., Andres et al, 2004;Andres et al, 2008;Lindemann et al, 2007;Namdar et al, 2014;Namdar and Ganel, 2018;Rugani et al, 2018;Rugani et al, 2017;Badets and Pesenti, 2010;Ranzini et al, 2011), similar interactions have also been observed for other magnitude domains. For example, when participants reached out to grasp a wooden block, their movements had a larger grip aperture after reading a word representing a larger object (e.g.…”

Neural activation patterns and connectivity in visual attention during Number and Non-number processing: An ERP study using the Ishihara pseudoisochromatic plates

“…Faster RT emphasizes faster nervous system processing time with faster muscular movement (Spirduso et al 1975), which defines as higher cognitive function (Gavkare et al [26]). Interestingly a recent study investigated the 'mental number line' which is oriented from left to right on the SNARC (spatial-numerical association of response codes) effect (faster response to the small number on the left side and to the large numbers on the right side) using kinematics of fingers movement besides response time and found that numerical processing affects action execution (Rugani et al [66]). Therefore, we used RT as a marker of cognitive processing speed in this study together with ERP.…”

Numerical Affordance Influences Action Execution: A Kinematic Study of Finger Movement

“…The open question is whether number processing influences only the grip component or the preceding reaching movement as well (grasp and transport components). To pursue this question in an unbiased way, we recently adopted a new and not-overlearned paradigm ( Rugani et al, 2017 ; see also Betti et al, 2015 for a previous application of this paradigm). We specifically combined a “free response” task with the kinematic analysis of a finger movement and we provided the first demonstration that numerical processing affect not only the grasping, but also the reaching component of movements.…”