Rear interaction zones of 140 smartphone models vs. Ergonomic recommendation

Abstract

Rear interaction is a new interaction method adopted by many recent smartphone models. This study compared the rear interaction zones of 140 smartphone models with Lee et al. (2016)'s recommendation, and examined the effects of smartphone width and height on the location of rear interaction zone. The mean center (X, Y) of the rear interaction zones of these smartphone models was (0.5, 111.6), while the center of the recommended zone was (11.5, 94.5). The mean (SD) distance (D) between the center of rear interaction zone of each model and the recommended center was 21.0 (4.8). The significant interaction effect of width × height on the location of the rear interaction zone indicated that larger models had higher rear interaction zones. Using the K-Means clustering method, the smartphone models were divided into three groups - Small (PS), Medium (PM), and Large (PL). The XY ranges of the rear interaction zones were (-6-16, 78-132) for PS, (-7-16, 99-134) for PM, and (-6-6, 91-140) for PL. The mean center of each smartphone group's interaction zones was deviated from the center of the recommended zone by 18.4mm for PS, 22.7mm for PM, and 24.7mm for PL. Only seven out of the 140 models provided a rear interaction zone that was partially overlapped with the recommended zone. It is recommended to lower the rear interaction zones provided by the current smartphone models regardless of their size in order to enhance hand comfort during rear interactions. Copyright 2017 by Human Factors and Ergonomics Society.