Background: In the last 2 decades, cognitive science and the transportation psychology field have dedicated a lot of effort to designing advanced driver support systems. Verbal warning systems are increasingly being implemented in modern automobiles in an effort to increase road safety.
Objective: The study presented here investigated the impact of directional speech alert messages on the participants' speed to judge whether or not naturalistic road scenes depicted a situation of impending danger.
Method: Thirty-eight volunteers performed a computer-based key-press reaction time task.
Results: Findings indicated that semantic content of verbal warning signals can be used for increasing driving safety and improving hazard detection. Furthermore, the classical result regarding signal accuracy is confirmed: directional informative speech messages lead to faster hazard detection compared to drivers who received a high rate of false alarms.
Conclusion: Notwithstanding some study limitations (lack of driver experience and low ecological validity), this evidence could provide important information for the specification of future Human-Machine-interaction (HMI) design guidelines.