Response of part-time belt users to enhanced seat belt reminder systems of different duty cycles and duration

Enhanced seat belt reminders are an effective means of increasing seat belt use. It is important to optimize the design of these systems so that they increase belt use and are acceptable to vehicle occupants. This study examined the effects of duty cycle and duration on seat belt reminder effectiveness and annoyance. It also evaluated the European New Car Assessment Programme (Euro NCAP) duration requirement. Eighty part-time belt users experienced one of four seat belt reminders in a driving simulator and rated the likelihood that they would buckle up and how annoyed they were every 45 s. Overall, participants that experienced an enhanced reminder said they would be more likely to buckle up than participants that experienced a basic reminder which complied with but did not exceed the US federal requirements. The reported likelihood of buckling up did not change significantly as reminder duration increased. Increasing the duty cycle of the chime and flashing icon in a reminder cycle did not influence these ratings either, but it did make the system more annoying. Reducing the duty cycle of enhanced reminders would be one method of increasing user acceptance while ensuring the reminder system still motivates belt use. Lastly, the variation in duration and duty cycle permitted under Euro NCAP requirements for seat belt reminders did not affect the reported likelihood of belt use for participants in the three enhanced reminder conditions.