Effects of Smartphone Size and Hand Size on Grip Posture in One-Handed Hard Key Operations

Younggeun Choi,Wonsup Lee,Jangwoon Park,Heecheon You,Xiaopeng Yang

doi:10.3390/app10238374

Abstract

Greater understanding of the grip postures preferred by users is needed for the ergonomic design of smartphone user interfaces. The present study identifies user-preferred grip postures by smartphone size and hand size in one-handed hard key operations. Grip postures of 45 participants were photographed while major smartphone tasks were simulated in standing with smartphone mockups of nine screen sizes (3.0″–7.0″). The grip postures were encoded by the locations (left side: L, right side: R, top: T, bottom: B, front: F, back: K) of a smartphone and the number of fingers at each contact location. Three grip postures (L3-R1-K1: 70.0%, L4-R1: 13.3%, L3-R1-T1: 12.0%) were found dominant and the distribution of grip posture changed by smartphone size and hand size—the larger the smartphone size or hand size, the higher the frequency of L3-R1-K1. The grip posture frequency distribution by smartphone size would be of use to determine the optimal locations of hard keys on a smartphone of a particular size.

Highlights

Greater understanding user-preferred grip postures in one-handed operation of hard keys on a smartphone is needed to determine their optimal locations for better operational efficiency and comfort
The frequency distribution of grip posture varied significantly by smartphone size, as shown in over the smartphone size range of 3.0 to 5.0 inches and levelled off in the smartphone size range of 5.0 to 7.0 inches, while that of L4-R1 gradually decreased from 21.1% to 6.7% over the smartphone size range of 3.0 to 7.0 inches and that of L3-R1-T1 linearly decreased from 39.3% to 2.2% over the smartphone size range of 3.0 to 5.0 inches and became negligible (
The skewness of a frequency distribution of the three dominant grip postures increased toward L3-R1-K1 as smartphone size increased: a slightly skewed frequency distribution

Summary

Introduction

Greater understanding user-preferred grip postures in one-handed operation of hard keys on a smartphone is needed to determine their optimal locations for better operational efficiency and comfort. The operational efficiency of the hard keys can be improved if they are properly located based on the information of user-preferred grip postures. Since one-handed (single hand) hard key operations have more usability problems than two-handed (both hands) hard key operations in terms of mobility of the fingers, comfort, efficiency of key operation, and stability of grip [3,4,5], the locations of the hard keys need to be determined by considering user-preferred grip postures in a one-handed hard key operation. No research has been conducted to examine the effects of task type, device size, and hand size on user-preferred grip posture to determine the proper locations of hard keys on a hand-held mobile

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Discussion

Conclusion