CHANGES IN DRIVER BEHAVIOR AS A FUNCTION OF HANDSFREE MOBILE PHONES -A SIMULATOR STUDY

The effects of a mobile telephone task on drivers' reaction time, lane position, speed level, and workload were studied in two driving condi tions (an easy or rather straight versus a hard or very curvy route). It was predicted that the mobile telephone task would have a negative effect on drivers' reaction time, lane position, and workload and lead to a reduction of speed. It was also predicted that the effects would be stronger for the hard driving task. The study was conducted in the VTI driving simulator. A total of 40 subjects, experienced drivers ag ed 23 to 61, were randomly assigned to four experimental conditions (t elephone and easy or hard driving task versus control and easy or hard driving task). Contrary to the predictions, the strongest effects wer e found when the subjects were exposed to the easy driving task. In th e condition where drivers had to perform the easy driving task, findin gs showed that a mobile telephone task had a negative effect on reacti on time and led to a reduction of the speed level. In the condition wh ere drivers had to perform the hard driving task, findings showed that a mobile telephone task had an effect only on the drivers' lateral po sition. Finally, the mobile telephone task led to an increased workloa d for both the easy and the hard driving task. The results are discuss ed in terms of which subtask, car driving or telephone task, the subje cts gave the highest priority. Some implications for information syste ms in future cars are discussed.