Conversing while driving: The importance of visual information for conversation modulation

Abstract Multiple studies have shown an increased accident risk due to telephoning while driving. On the other hand, driving with passengers leads to a decreased accident risk. One explanation is a conversation modulation by passengers in cars which leads to a different conversation pattern which is not so detrimental to driving as that when phoning. A driving simulator study was conducted in order to examine this conversation modulation more closely and to find out more about the factors involved in this modulation, especially about the role of visual information available to the passenger. In a within-subject design the conversational patterns of 33 drivers and passengers in different in-car settings (passenger as usual, passenger without front view or passenger without view of the driver) were compared to a hands-free cell phone and to a hands-free cell phone with additional visual information either about the driving situation or the driver. Participants were instructed to have a naturalistic small-talk with a friend. Results of the drivers’ speaking behavior showed a reduction of speaking while driving. Compared to a conversation partner on the cell phone, a passenger in the car varies his speaking rhythm by speaking more often but shorter. Further analyses showed that this effect is also found with a cell phone when providing the conversation partner additional visual information either about the driving situation or the driver. This latter finding supports the idea that conversation modulation is not triggered by being in the car but by the visual information about the driver’s state and the driving situation.