Messages beyond the phone: Processing variable message signs while attending hands-free phone calls

• Published in: Accident analysis and prevention Vol. 150; p. 105870
• Main Authors: Tejero, Pilar, Roca, Javier
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.02.2021
• Subjects: Cognitive control; Cognitive distraction; Cognitive effort; Driving performance; Hands-free phone; Variable message signs; Cognitive distraction; Cognitive effort; Driving performance; Cognitive control; Hands-free phone; Variable message signs
• ISSN: 0001-4575; 1879-2057
• DOI: 10.1016/j.aap.2020.105870

•Hands-free phone calls differentially affect high- and low-demand driving tasks.•Visuospatial phone questions increased errors responding to variable message signs.•Information processing of variable message signs was less stable with phone calls.•Visuospatial and conceptual phone questions increased cognitive effort (heart rate).•Cognitive distraction had no effect on vehicle speed or lateral position. We examined the effects of different types of cognitive distraction coming from a hands-free phone conversation on the processing of information provided by variable message signs (VMS), on driving performance indicators, and on a physiological index of mental effort (heart rate). Participants drove a route in a driving simulator and had to respond to VMS messages under three conditions: no-distraction, visuospatial distraction (attending phone calls with questions inducing visuospatial processing), and conceptual distraction (attending phone calls with questions requiring semantic memory). Results showed more errors responding to VMS messages in the visuospatial distraction condition. In addition, both types of questions increased the intraindividual variability of response distances and the heart rate, as compared to the no-distraction condition. These results provide new evidence that talking on a hands-free phone entails costs in the processing of traffic information (in particular, text messages displayed on VMS) and it increases the driver’s cognitive effort. Interestingly, the cognitive distraction had no effect on the driver’s control of the vehicle speed or lateral position. Therefore, the effects of potential risk factors can critically vary among the different driving subtasks due to modulatory factors, such as the level of attentional task demands (relatively high in the processing of messages on VMS, but relatively low in controlling the speed and lateral position of the vehicle in quiet traffic conditions). In consequence, the current paper provides new evidence to discuss hands-free phone policies and highlights the importance of designing technological countermeasures to prevent drivers missing critical information displayed on VMS.