"Watch Out!" - Semi-Autonomous Vehicles Using Assertive Voices to Grab Distracted Drivers' Attention.

Semi-autonomous vehicles are gradually appearing on our roads, and have already been involved in several high-profile accidents. These accidents usually occurred because the driver did not intervene in time when the automated system failed. An important issue for the design of future semi-autonomous vehicles is identifying effective methods for alerting drivers to critical events that require their intervention. To investigate this, we report the results of a lab-based simulator study in which participants had to respond to driving events while also playing an immersive mobile game on a phone. Results show that a more assertive voice alerting the driver to driving events resulted in faster reaction times and was perceived as more urgent than a less assertive voice, regardless of how immersed the driver was in the mobile game. These results suggest that the designers of future semi-autonomous vehicles should use assertive voice commends to alert drivers to critical events that require their intervention.