Sungryul Park

Effects of display curvature and hand length on smartphone usability

The purpose of this study was to examine the effects of display curvature and hand length on smartphone usability, which was assessed in terms of grip comfort, immersive feeling, typing performance, and overall satisfaction. A total of 20 younger individuals with the mean (SD) age of 20.8 (2.4) yrs were divided into three hand-size groups (small: 8, medium: 6, large: 6). Two smartphones of the same size were used – one with a flat display and the other with a side-edge curved display. Three tasks (watching video, calling, and texting) were used to evaluate smartphone usability. The smartphones were used in a landscape mode for the first task, and in a portrait mode for the other two. The flat display smartphone provided higher grip comfort during calling (p = 0.008) and texting (p = 0.006) and higher overall satisfaction (p = 0.0002) than the curved display smartphone. The principal component regression (adjusted R2 = 0.49) of overall satisfaction on three principal components comprised of the remaining measures showed that the first principal component on grip comfort was more important than the other two on watching experience and texting performance. It is thus necessary to carefully consider the effect of display curvature on grip comfort when applying curved displays to hand-held devices such as smartphones.

Effects of Display Curvature and Task Duration on Proofreading Task Performance, Visual Fatigue, Visual Discomfort, and Display Satisfaction:

With more curved display products in the market and more exposure to such products, it is necessary to examine the effects of display curvature and task duration from the ergonomics perspective. The current study examined the effects of these two factors on visual performance, visual fatigue, visual discomfort, and display satisfaction during proofreading tasks. We incorporated five display curvatures (600R, 1140R, 2000R, 4000R, and flat) and five task durations (0, 15, 30, 45, and 60 min). Each of 50 individuals completed a 1-hr proofreading task at one of five display curvature conditions. The horizontal viewing distance was fixed at 600mm. Proofreading performance (speed and error rate), subjective visual fatigue [on ECQ (Eye Complaint Questionnaire)], physiological visual fatigue [CFF (Critical Fusion Frequency), blink duration, and blink frequency], visual discomfort (on VAS), and display satisfaction (on VAS) were measured. The highest mean proofreading speed was at 600R. The mean proofreading speed and error rate increased by 15.5% and 22.3%, respectively, over the 1-h task. The mean ECQ score and visual discomfort increased by 188.6% and 107.2% during 45 and 60 min of the task, respectively. The mean CFF and display satisfaction decreased by 0.49Hz and 11.2% during 15 and 15-45 min of the task. A polynomial regression model for subjective visual fatigue was developed (adjusted R2 = 0.6). These findings can be used when determining ergonomic display curvatures and predicting visual fatigue.