The effect of hand position on perceived finger orientation in left- and right-handers

Abstract

In the absence of visual feedback, the perceived orientation of the fingers is systematically biased. In right-handers these biases are asymmetrical between the left and right hands in the horizontal plane and may reflect common functional postures for the two hands. Here we compared finger orientation perception in right- and left-handed participants for both hands, across various hand positions in the horizontal plane. Participants rotated a white line on a screen optically superimposed over their hand to indicate the perceived position of the finger that was rotated to one of seven orientations with the hand either aligned with the body midline, aligned with the shoulder, or displaced by twice the shoulder-to-midline distance from the midline. We replicated the asymmetric pattern of biases previously reported in right-handed participants (left hand biased towards an orientation ~30° inward, right hand ~10° inward). However, no such asymmetry was found for left-handers, suggesting left-handers may use different strategies when mapping proprioception to body or space coordinates and/or have less specialization of function between the hands. Both groups’ responses rotated further outward as distance of the hand from the body midline increased, consistent with other research showing spatial orientation estimates diverge outward in the periphery. Finally, for right-handers, precision of responses was best when the hand was aligned with the shoulder compared to the other two conditions. These results highlight the unique role of hand dominance and hand position in perception of finger orientation, and provide insight into the proprioceptive position sense of the upper limbs.

The signing body: extensive sign language practice shapes the size of hands and face

“…However, within the SL group, worse performance (i.e., more distortion) was demonstrated at the estimation of finger length compared to that of the dorsum. This confirmed the association of body size representation with specific use and functional experience (Caggiano and Cocchini 2020 ; Ferretti 2016 ; Fraser and Harris 2016 , 2017 ; Romano et al 2019 ), and not with an overall bias to underestimating lengths. In other words, the larger underestimation of length was specific for fingers, and not a general tendency affecting the whole hand.…”

“…Owing to the idea of manual practice and functional workspace (Fraser and Harris 2016 , 2017 ), differences in the representation of the hands were only seen in the near-reaching space, within the boundaries of the signing space, and not in the far-reaching space, whereby performance between groups was not significantly different. This was due to a reduction of the gain by the SL group in near-reaching space from 38.46 to 17.88% in far-reaching space.…”

The Influence of Hand Dominance in Wrist Fracture Post-Operative Functional Evaluation

“…Hand dominance has been found to affect perceived finger orientation and proprioception. 33 The study by Fraser et al highlights the complexity of proprioception sense, and how this sense is affected by different factors such as use and regular posturing. 33…”

“…33 The study by Fraser et al highlights the complexity of proprioception sense, and how this sense is affected by different factors such as use and regular posturing. 33…”