Investigation of icon design and touchable area for effective smart phone controls

Youngjae Im, Taeil Kim, Eui S. Jung

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


As the full-touch screen is being implemented in more smart phones, controllability of touch icons need to be considered. Previous research focused on recommendations for absolute key size. However, the size of tactual input on touch interface is not precisely equal to the icon size. This study aims to determine the suitable touchable area to improve touch accuracy. In addition, there was an investigation into the effect of layout (3 × 4, 4 × 5, 5 × 6, and 6 × 8) and icon ratio (0.5, 0.7, and 0.9). To achieve these goals, 40 participants performed a set of serial tasks on the smart phone. Results revealed that the layout and icon ratio were statistically significant on the user response: input offset, hit rate, task completion time, and preference. The 3 × 4 and 4 × 5 layouts were shown to have better performance. The icon ratio of 0.9 was shown to have greater preference. Furthermore, the hit rate (proportion of correct input) of touchable area was estimated through the bivariate normal distribution of input offset. The hit rate could vary, depending on the size of touchable area, which is a rectangle that yields a specific hit rate. A derivation procedure of the touchable area was proposed to guarantee the desirable hit rate. Meanwhile, the locations of the central region indicated a pattern of vertical touch and showed better performance. The users felt more difficulty when approaching the edge of the frame. The results of this study could be used in the design of touch interfaces for mobile devices.

Original languageEnglish
Pages (from-to)251-267
Number of pages17
JournalHuman Factors and Ergonomics In Manufacturing
Issue number2
Publication statusPublished - 2015 Mar 1


  • Controllability
  • Hit rate
  • Icon design
  • Smart phone design
  • Touchable area

ASJC Scopus subject areas

  • Human Factors and Ergonomics
  • Industrial and Manufacturing Engineering


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