Influence of size and location of buttons on the usability of interface on large touch screens

Abstract

This study examined how large touchscreen buttons affect user task completion time, error rate, and subjective satisfaction (ease of pointing and clicking on targets). In this experiment, 31 participants completed button click tasks of square targets placed at 30 (5 × 6) different locations, with seven button sizes (10 mm, 30 mm, 50 mm, 70 mm, 90 mm, 110 mm, and 130 mm). Repeated measures ANOVAs showed that on a 65'' large touch screen (W 1428 × H 803 mm), 70 mm buttons achieved essentially the best performance in completion time, 50 mm in error rates, and 90 mm in subjective satisfaction, respectively. We also compare the differences in efficiency among different button areas and button sizes. The surrounding area and lower area require a bigger button size to achieve the best performance in terms of error rates and subjective satisfaction. The right area requires a bigger optimal button size than the left area considering error rates, while it is the opposite for subjective satisfaction.

Practitioner summary: This study investigates how the size and location of buttons on the increasingly popular large touch screen affect user experience. The study reveals that 70, 50, 90 mm size buttons are recommended when speed, accuracy and satisfaction are priorities respectively. The interaction between button size and button area is significantly different. The surrounding area and lower area require a bigger button size to achieve the best performance in terms of error rate and subjective satisfaction. Considering error rates, the right area requires a bigger optimal button size than the left area, while it is opposite for subjective satisfaction. These findings could facilitate the optimal design of usable large touch screens.

Keywords:

• Large touch screen
• button size
• button location
• interface usability

Acknowledgments

The authors would like to express their sincere gratitude to Fengqi Wang and Weijie Zhong at Shiyuan Innovation Design Institute for providing experimental equipment. We would also like to thank the graduate students of the Neuroaesthetics and Design Laboratory for their help in data collection.

Declaration statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was funded by grants from the Humanity and Social Science Youth Foundation of Ministry of Education of China (19YJCZH041), the 13th Five-Year Planning for Philosophy and Social Science of Guangdong Province (GD18YXL01).