Smartphone form factors: Effects of width and bottom bezel on touch performance, workload, and physical demand

Seul Chan Lee, Min Chul Cha, Hwan Hwangbo, Sookhee Mo, Yong Gu Ji

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


This study aimed at investigating the effect of two smartphone form factors (width and bottom bezel) on touch behaviors with one-handed interaction. User experiments on tapping tasks were conducted for four widths (67, 70, 72, and 74 mm) and five bottom bezel levels (2.5, 5, 7.5, 10, and 12.5 mm). Task performance, electromyography, and subjective workload data were collected to examine the touch behavior. The success rate and task completion time were collected as task performance measures. The NASA-TLX method was used to observe the subjective workload. The electromyogram signals of two thumb muscles, namely the first dorsal interosseous and abductor pollicis brevis, were observed. The task performances deteriorated with increasing width level. The subjective workload and electromyography data showed similar patterns with the task performances. The task performances of the bottom bezel devices were analyzed by using three different evaluation criteria. The results from these criteria indicated that tasks became increasingly difficult as the bottom bezel level decreased. The results of this study provide insights into the optimal range of smartphone form factors for one-handed interaction, which could contribute to the design of new smartphones.

Original languageEnglish
Pages (from-to)142-150
Number of pages9
JournalApplied Ergonomics
Publication statusPublished - 2018 Feb

Bibliographical note

Publisher Copyright:
© 2017

All Science Journal Classification (ASJC) codes

  • Human Factors and Ergonomics
  • Physical Therapy, Sports Therapy and Rehabilitation
  • Safety, Risk, Reliability and Quality
  • Engineering (miscellaneous)


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