Passenger and Cell-Phone Conversations in Simulated Driving

Previous work on use of cell phones while driving compared cell phone conversations while driving with driving only conditions. This study investigated how conversing on a cell phone differs from conversing with a passenger. Participants conversed about close-call situations they experienced. We compared how well drivers followed task instructions when driving only, when driving and conversing on a cell phone, and when driving and conversing with a passenger. The results show that the number of driving errors was highest in the cell-phone condition. Analyzing the conversations we found that in passenger conversations more references were made to traffic and more turn taking followed those references than in cell phone conversations. The results show that passenger conversations differ from cell phone conversations because the surrounding traffic becomes a topic of the conversation, helping driver and passenger to share situation awareness, and mitigating the potential effects of conversation on driving.