Smaller is Better, Tablet Users Find

Photo: Study subject holding tablet with the left hand while posture and muscle activity are recorded.
Study subject holding tablet with the left hand while posture and muscle activity are recorded.

People on the go may be more comfortable and productive using small to mid-size hand-held tablets compared to larger ones, according to researchers at the University of California. Adding a ledge or handle grip also increases its usability and decreases fatigue, their study concludes.

“Users showed a high preference towards comfort,” says alumna Anna Pereira, PhD ‘13, lead author of the paper published in Ergonomics. “When you’re in a mobile environment there’s a trade-off between what you carry and hold versus productivity. But users are pointing toward smaller devices.”

Applications of mobile technology continue to surge as more and more organizations realize their potential. Yet there is a gap of empirical evidence on tablet and smart phone design features that increase usability and biomechanics, the authors report. Unlike desktops, no national design guidelines exist for hand-held computers.

“As smart phones and tablets become more prominent, we were curious to look at how people are going to use them in a mobile environment and how we can start to design for that,” said Pereira, who is now a researcher on the Surface Team at Microsoft.

Photo: Pictures of the tablets and tablet features tested in the study. The largest tablet is the size of an iPad.
Pictures of the tablets and tablet features tested in the study. The largest tablet is the size of an iPad.

The study involved 15 men and 15 women ages 16 to 64 years. Participants performed tasks using eight tablets and three styluses. Standing, they held the tablet in their left hand and touched a prototype screen with their right while researchers measured user preference, productivity, fatigue, muscle activity, posture, shoulder movement, tablet tilt, and eye distance.

Tablet size and weight had an effect on usability, fatigue, and biomechanics. Participants favored small to mid-size tablets and rated a ledge or handle grip significantly better for not dropping the tablet. They estimated they could hold small to mid-size tablets twice as long as large tablets. The large tablet was similar in size to the iPad and the mid-size was similar to an iPad mini.

Usability and fatigue improved with a ledge or handle grip compared to a flat grip, which suggests “adding a handle or a textured grip is useful for mobile settings,” according to Pereira.

The study included co-investigators Tevis Miller, Yi-Min Huang, Dan Odell, and David Rempel from the School of Public Health and Department of Bioengineering and received funding from the National Institute for Occupational Safety and Health. Pereira conducted the study while she was a PhD student in the Environmental Health Sciences – Ergonomics Program at UC Berkeley.

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