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Tablet keyboard configuration affects performance, discomfort and task difficulty for thumb typing in a two-handed grip.

Trudeau MB; Catalano PJ; Jindrich DL; Dennerlein JT
PLoS One 2013 Jun; 8(6):e67525
When holding a tablet computer with two hands, the touch keyboard configuration imposes postural constraints on the user because of the need to simultaneously hold the device and type with the thumbs. Designers have provided users with several possible keyboard configurations (device orientation, keyboard layout and location). However, potential differences in performance, usability and postures among these configurations have not been explored. We hypothesize that (1) the narrower standard keyboard layout in the portrait orientation leads to lower self-reported discomfort and less reach than the landscape orientation; (2) a split keyboard layout results in better overall outcomes compared to the standard layout; and (3) the conventional bottom keyboard location leads to the best outcomes overall compared to other locations. A repeated measures laboratory experiment of 12 tablet owners measured typing speed, discomfort, task difficulty, and thumb/wrist joint postures using an active marker system during typing tasks for different combinations of device orientation (portrait and landscape), keyboard layout (standard and split), and keyboard location (bottom, middle, top). The narrower standard keyboard with the device in the portrait orientation was associated with less discomfort (least squares mean (and S.E.) 2.960.6) than the landscape orientation (4.560.7). Additionally, the split keyboard decreased the amount of reaching required by the thumb in the landscape orientation as defined by a reduced range of motion and less MCP extension, which may have led to reduced discomfort (2.760.6) compared to the standard layout (4.560.7). However, typing speed was greater for the standard layout (12765 char./min.) compared to the split layout (11364 char./min.) regardless of device orientation and keyboard location. Usage guidelines and designers can incorporate these findings to optimize keyboard design parameters and form factors that promote user performance and usability for thumb interaction.
Electronic devices; Musculoskeletal disorders; MSD; Posture; Keyboards; Laboratory testing; Task performance; Extremities; Mobile equipment; Ergonomics
Publication Date
Document Type
Journal Article
Email Address
Funding Type
Fiscal Year
Identifying No.
Grant-Number-R01-OH-008373; Grant-Number-T42-OH-008416
Issue of Publication
Source Name
Public Library of Science One
Performing Organization
Harvard University School of Public Health
Page last reviewed: May 11, 2023
Content source: National Institute for Occupational Safety and Health Education and Information Division