Compatibility between object size and response side in grasping: the left hand prefers smaller objects, the right hand prefers larger objects.

Christian Seegelke,Peter Wühr

doi:10.7717/peerj.6026

Abstract

It has been proposed that the brain processes quantities such as space, size, number, and other magnitudes using a common neural metric, and that this common representation system reflects a direct link to motor control, because the integration of spatial, temporal, and other quantity-related information is fundamental for sensorimotor transformation processes. In the present study, we examined compatibility effects between physical stimulus size and spatial (response) location during a sensorimotor task. Participants reached and grasped for a small or large object with either their non-dominant left or their dominant right hand. Our results revealed that participants initiated left hand movements faster when grasping the small cube compared to the large cube, whereas they initiated right hand movements faster when grasping the large cube compared to the small cube. Moreover, the compatibility effect influenced the timing of grip aperture kinematics. These findings indicate that the interaction between object size and response hand affects the planning of grasping movements and supports the notion of a strong link between the cognitive representation of (object) size, spatial (response) parameters, and sensorimotor control.

Highlights

According to ‘‘A Theory of Magnitude’’ (ATOM), there exists a generalized magnitude system in the brain, that processes quantities such as space, size, number, time, and other magnitudes using a common neural metric (Walsh, 2015; Walsh, 2003)
We address two domains whose potential interactions have largely been neglected in the literature, but clearly are relevant for sensorimotor control: physical object size and space
movement time (MT) were shorter with the compatible than the incompatible mapping, whereas the opposite was true for the left hand

Summary

Introduction

According to ‘‘A Theory of Magnitude’’ (ATOM), there exists a generalized magnitude system in the brain, that processes quantities such as space, size, number, time, and other magnitudes using a common neural metric (Walsh, 2015; Walsh, 2003). This notion is supported by studies showing interaction effects between several dimensions addressed in ATOM such as number and space (Dehaene, Bossini & Giraux, 1993; Winter et al, 2015), number and size (Henik & Tzelgov, 1982; Reike & Schwarz, 2017), time and space. The SNARC effect has led to the suggestion that numbers are spatially organized along a mental number line (MNL) with small numbers represented to the left and large numbers to the right (Restle, 1970; Dehaene, Bossini & Giraux, 1993)

Methods

Results

Discussion

Conclusion