Building a Better Mouse

BingYune Chen in the UCSF-UCB Ergonomics Laboratory. Photo credit: Abby CohnBingYune Chen in the UCSF-UCB Ergonomics Laboratory. (Photo by Abby Cohn.)Computer mice are a weighty matter for BingYune Chen.

Chen, a senior who graduates this month in bioengineering, is studying how weight affects the speed, accuracy and ease of use of a computer mouse. “It’s a new issue,” says the 22-year-old Chen, who helped conduct a pilot project as an undergraduate researcher at the UCSF–UCB Ergonomics Laboratory, where he is now an employee. While extensive research has been done on the design of computer mice, Chen says, little is known about mouse weight and its impact on performance. The experiment, conducted at the lab facility at UC’s Richmond Field Station, was largely funded by Microsoft.

After recruiting 24 volunteer subjects who were regular computer users, Chen ran them through a battery of point-and-click tasks of varying difficulty. They manipulated four mice weighing 90, 120, 150 and 180 grams, corresponding to the weights of mice currently being manufactured. Participants tested each mouse for 20 minutes with a software program that uses a variety of icons and other targets and enabled Chen to calculate speed, accuracy and “acceleration” or force. “We tried to cover the whole range of activities standard computer users would come across,” says Chen. Participants also answered a questionnaire addressing preferences and any discomfort they may have experienced.

The preliminary findings: weight may make a difference. The 90-gram mouse was more accurate than the 150-gram model when test subjects performed more complicated maneuvers, Chen says. Participants also reported preferring the 90- and 120-gram mice over the 180-gram version.

More extensive studies are needed to build on the experiment, Chen says, but for him the mouse project and other ergonomics research he’s conducted at the lab have been transformative. “Working in this lab, I just really got interested in the field,” he says. “The whole idea is preventive medicine, coming up with solutions before the problems occur.” Chen, who is from San Bernardino, plans to continue working in the lab when he enters UC Berkeley’s Master of Public Health program this fall.

The Ergonomics Lab, jointly operated by UC San Francisco and UC Berkeley, conducts studies aimed at reducing the risk of chronic injuries from a wide variety of workplace tools and equipment. Although it specializes in computer keyboards and mice, the lab has also investigated pipettes in the biotech industry, pruning tools for agricultural work and chairs for sewing machine operators. Lab director David Rempel, who designed the study on mouse weight, encourages undergraduate interns to take an active role in research. “It helps everyone,” says Rempel, who holds joint appointments at UCSF and UC Berkeley’s Department of Bioengineering. Researchers “need help with their projects, and the undergraduates learn a lot.”

Chen got immediate hands-on experience when he started volunteering in the summer of 2006. His first project involved a new cake decorating device intended to reduce the incidence of carpal tunnel syndrome and wrist injuries suffered by professional cake decorators. “I looked at hand and arm biomechanics,” says Chen, who helped study 17 cake decorators applying frosting with a new trigger-controlled device and with the old-fashioned method of squeezing a piping bag. The work fueled Chen’s interest in ergonomics. Its other consequence was more gastronomic. After watching decorators spread gallons of frosting, he recalls, “I couldn’t eat pastries that whole summer.”

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