Effects of Voluntary Handheld vs. Speech-Based Text Entry on Driving Performance in (Un)Predictable Critical Situations

It is often suggested that speech-based entry systems for text messages might provide a solution for the safety problems that arise because of handheld texting. However, although such systems have the advantage of allowing drivers to keep their eyes on the road, there is still a considerable portion of cognitive load associated with texting, which might impair the processing of relevant information. At the same time, drivers do not tend to text always and everywhere, but rather only in situations, they consider “suitable”. The selection of relevant test scenarios, and the free choice to (not) text in these scenarios are key aspects in the investigation of the effects of texting that have often been neglected. The aim of this experiment was to investigate the consequences of voluntary visual-manual and speech-based text messaging on reaction time and crashes in critical situations that might or might not be anticipated with the help of an environmental cue. We conducted a driving simulator study in which at one point, a child crossed the road, sometimes preceded by a ball rolling across, sometimes not. Participants (82, three groups: handheld writing, speech-based entry, control group) were free to (not) engage in a texting task while driving. While the pre-information had a positive impact on brake reaction time, there were no significant differences between the different groups in either crash rate or brake reaction time. The results highlight the role the design of test scenarios plays for the effects of texting on driving performance