Effects of Hands-Free Device Conversation and Operation on Driving Performance

Abstract

The aim of this study was to examine impacts of cell phone conversation and operation on the driving performance. Ten male students participated in following two experiments: one is to examine the effect of cell phone conversation on driving performance, and the other is to examine the effect of cell phone operation while driving. In the former experiment, the subjects performed No-task and conversation (cognitive tasks) with hands-free (HF) and hand-held (HH) cell phone while driving in city traffic in which the maximum speed limit is 40 km/h. In the latter experiment, they were instructed to operate (dialing or talking) HH and HF such as touch screen, earphone, and voice recognition while driving. We measured driving performance, heart rate, eye tracking, and NASA-TLX. The results were as follows: (1) Regardless of phone type, cell phone conversation while driving increased the drivers' psychophysiological stress and also had negative impacts on the driving performance. (2) Break reaction time in response to pop-up event was significantly slower in operation of both HH and all hands-free kits than in No-task. The results suggest that using all hands-free cell phone while driving is not safer than hand-held cell phone or driving without a cell phone; inattentional blindness itself may be a risk factor for traffic accidents.