A persistent seat belt reminder system that chimes for up to five minutes gets an increased number of drivers to use their safety belts, an insurance industry safety group said on Dec. 20. The Insurance Institute for Highway Safety (IIHS) said the chime, fitted to recently made Ford Motor Co. vehicles, increased driver belt use to 76 percent from 71 percent in a study conducted in Oklahoma. Seat belt reminders in other vehicles usually chime for no more than eight seconds when started, as mandated by the U.S. federal government, according to IIHS. If a driver doesn't buckle up under the Ford system, a light flashes and a chime sounds for six seconds followed by a 30-second pause before repeating the cycle for up to five minutes. The IIHS said the gains were important because it was hard to change the behaviour of the minority of motorists who still don't buckle up despite evidence about the effectiveness of seat belts and laws requiring their use. "It has proven difficult to get these people to buckle up, and vehicle-based systems like Ford's clearly help," said Allan Williams, the insurance Institute's chief scientist. The system probably motivates these drivers to buckle up more through the annoyance factor than through any newfound awareness of seat belt safety, according to at least one industry observer. Ford's belt reminder system is in some 2000 model year vehicles, most 2001 models and all its 2002 products. The study was conducted by observing driver belt use when cars were brought in for service at 12 dealerships in Tulsa and Oklahoma City during August and September.