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Fundamental study on the size and inter-key spacing of numeric keys for touch screen
H Harada1, T Katsuura, Y Kikuchi
1Department of Ergonomics, Faculty of Engineering, Chiba University, Japan.
Journal of Human Ergology
|December 1, 1996
Summary
For optimal touch screen performance, numeric square keys should be larger than 21 mm, with inter-key spacing between 3-6 mm. Smaller key sizes and zero spacing increase errors and slow response times.
Area of Science:
- Human-Computer Interaction
- Usability Engineering
- Ergonomics
Background:
- Touch screen interfaces are ubiquitous, yet optimal design parameters for numeric keypads remain crucial for efficient user interaction.
- Key size and spacing significantly impact data entry speed and accuracy on touch devices.
Purpose of the Study:
- To determine the optimal size and inter-key spacing for numeric square keys on touch screens.
- To identify key dimensions that minimize response times and error rates during data entry tasks.
Main Methods:
- A controlled experiment involving nine student participants (six male, three female) performing data entry tasks.
- Systematic variation of numeric key sizes (6-39 mm) and inter-key spacing (0-21 mm).
- Measurement of response times, error rates, and subjective user ratings.
Main Results:
- Key sizes of 21 mm and 30 mm yielded significantly faster response times than 6 mm and 12 mm keys (p < 0.001).
- A 6 mm key size resulted in significantly more errors compared to larger key sizes (p < 0.05).
- Inter-key spacing of 3 mm significantly improved response times (p < 0.001) and reduced errors compared to 0 mm spacing.
Conclusions:
- Optimal numeric square key size for touch screens should exceed 21 mm.
- Recommended inter-key spacing ranges from 3 mm to 6 mm for improved usability.
- Key size optimization must consider device screen size limitations.