Windows and other graphic programs have made the mouse ubiquitous, its use accounting for as much as two thirds of computer time. Few large studies have addressed the impact of this input device. That represented a fraction of total claims but 6.1 percent of RSIs from computer use. The Occupational Safety and Health Administration has begun eking out national ergonomic standards to identify and reduce workplace risks. Trouble is, most computer users develop disorders because they ignore warnings like tingling fingers, a numb hand, or a sore shoulder.
Cures are elusive, partly because RSIs present a grab bag of ills that often defy easy diagnosis.
Social factors sometimes intrude. Much of the apparent mouse threat would vanish if users parked their input device in a better spot, according to a study by Boston University's School of Occupational Therapy. Complaints eased once keyboard extenders placed the mouse closer to the space bar. Unconscious habits also can make matters worse. People tend to squeeze a mouse harder when trying to aim it precisely, notes Chris Plott, senior ergonomist at U S West.