In-vehicle alerting system for older and younger drivers - Does experience count?

Experienced older drivers and relatively inexperienced younger drivers drove a simulator equipped with a headway detection and alerting device (HDAD): The device alerted the driver when the time headway (TH) to the lead car was too short. The device occasionally emitted false alarms on the basis of a predefined reliability level. The HDAD was not activated for the control group. The experimental groups that drove with the HDAD maintained a TH within an "optimal" zone (2 s <= TH <= 4 s) during significantly more of the driving time than the control group. Drivers who used the HDAD discriminated between true alerts and false alarms and responded more often to true alerts. All groups maintained, on average, a safe headway (> 2 s). Although the average time in the danger zone was different for the younger and the older drivers, the variance within both groups, especially within the older driver group, was large and neutralized the difference. When the reliability of HDAD was the highest (99%), the driver's headway was shorter, although it was still well within the safe range. This could indicate increased confidence inspired by a very reliable device. Although multiple auditory stimuli were clearly defined during the experiment, they still caused confusion, especially for the older drivers, and may have hindered better performance. The results associate conflicting auditory signals as possible deterrents to the effective use of in-car aids for older drivers who may have trouble dividing attention among the inputs. Suggestions are given as to how in-car driver-aid interfaces can be improved for older drivers.