The Bias toward the Right Side of Others Is Stronger for Hands than for Feet

Chiara Lucafò,Federico Smerilli,Luca Tommasi,Przemysław Zdybek,Daniele Marzoli,Gianluca Malatesta,Cosimo Ferrara

doi:10.3390/sym13010146

Chiara Lucafò, Federico Smerilli + Show 5 more

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https://doi.org/10.3390/sym13010146

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Abstract

As shown by a series of previous studies, ambiguous human bodies performing unimanual or unipedal actions tend to be perceived more frequently as right-handed or right-footed rather than left-handed or left-footed, which indicates a perceptual and attentional bias toward the right side of others’ body. However, none of such studies assessed whether the relative strength of such a bias differs between the upper and lower limbs. Indeed, given that the prevalence of right-handedness is slightly larger than that of right-footedness, and given that hands provide more information than feet as regards both communicative and aggressive acts, it is plausible that the bias toward the right side of human bodies should be stronger for the hand than for the foot. We performed three experiments in each of which participants had to indicate the rotating direction (revealing the perceived handedness/footedness) of ambiguous human figures with either one limb (arm or leg) or two limbs (one arm and the contralateral leg) extended. The hypothesized advantage of the right hand over the right foot was found in both the second and the third experiment.

Highlights

Handedness, which refers to the preferential use of one limb over the other for manual activities, is the most studied behavioral asymmetry in humans [1]
Most research studying human motor asymmetry initially concerned handedness, there has been a growing interest for foot preference [2]. This topic came to be popular probably because footedness might be a less biased measure of lateral preference than handedness (e.g., [3]), foot preference being less influenced by environmental and social factors, and/or by years of practice in performing complex unilateral tasks compared with hand preference [4,5,6,7]
This might be linked to several factors, including the aforementioned difference between hands and feet with regard to external influences and asymmetrical practice [4,5,6,7], the fact that mixed-handedness is less frequent (2–7%) compared with mixed-footedness (26–35%; [7]), and the observation that the concordance between handedness and footedness is more common among righthanders than among left-handers [9,10,11,12,13]

Summary

Introduction

Handedness, which refers to the preferential use of one limb over the other for manual activities, is the most studied behavioral asymmetry in humans [1]. Laterality surveys indicate that the prevalence of dextral bias appears to be larger for handedness than for footedness (e.g., 88.2% vs 83.2%; [8]) This might be linked to several factors, including the aforementioned difference between hands and feet with regard to external influences and asymmetrical practice [4,5,6,7], the fact that mixed-handedness is less frequent (2–7%) compared with mixed-footedness (26–35%; [7]), and the observation that the concordance between handedness and footedness is more common among righthanders than among left-handers [9,10,11,12,13]. A perceptual frequency effect [15]

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