Analysis of Grip Posture for Ergonomic Smartphone Interface Design

Abstract

Grip posture needs to be considered to ergonomic smartphone interface design for better usability in terms of controllability, user performance, and stability. The present study is intended to objectively classify grip postures of smartphone when users conduct tasks with hard keys. Forty five smartphone users conducted tasks with nine smartphone mock-ups in different sizes. Two cameras were located above and under a smartphone mock-up and recorded synchronized videos of grip postures. The grip postures of smartphone were classified by counting the number of fingers at each side of smartphone. Three dominant grip postures of smartphone were identified in the experiment: (1) 3-finger left, 1-finger right, and 1-finger back support (70.0%), (2) 4-finger left and 1-finger right (13.3%), and (3) 3-finger left, 1-finger right, and 1-finger top (12.0%). Device size, hand width, and hand length were found significantly influential to grip posture. The grip postures identified in the present study would be of use in ergonomic smartphone interface design.