Impact of distracting activities and drivers' cognitive failures on driving performance

The rapid increase in the availability of smart phones and other infotainment devices, and their widespread use while driving, contributes significantly to car crash rates. This is since the human brain has limited capacity and cannot perform two tasks at the same time, but rather switches from one to another rapidly. Understanding of the impact of distracting activities on drivers’ behavior is essential in order to support the development of effective technology and policy solutions to mitigate its potential risk. The main objective of this study is to investigate the impact of several distracting activities, drivers’ characteristics, their reported frequency of involvement in distracting activities, and cognitive failures on driving performance. A driving simulator experiment was developed to collect data on several driver performance measures while undertaking different distracting activities. 101 volunteer drivers participated in the study (68 males and 33 females) with age range between 18 to 57 years old. Each driver drove four scenarios on two-lane rural highway, while undertaking various activities: (1) using a hand-held cell-phone; (2) texting; (3) eating; and (4) a control scenario (no distracting activity). In all of these scenarios the distracting activity started with the beginning of the scenario and lasted till the scenario ended. Each scenario took on average 4 minutes. During the scenarios the speeds of the other vehicles in front of the subject varied between 20-100 km/h, and their acceleration and decelerations varied between 0.4-2.5 m/sec2. The speeds and accelerations were chosen randomly from pre-defined uniform distributions. Data on the longitudinal and lateral movements of the vehicles were recorded in the experiment and various measures were calculated and extracted from this raw data. In addition, all participants completed a questionnaire on their personal characteristics, their frequency of involvement in distracting activities and level of distractibility, and the “The Cognitive Failures Questionnaire”. Significant differences were found in the driving performance measures among the distracting activities. In particular, texting had the largest negative effect on driving performance. It increased the variability in driving speeds, lateral deviations and the distance gaps from the lead vehicle. Similar but milder effects were also found for the other two distracting activities. Gender effect was small and insignificant, except in the lateral deviations, in which males had lower values. Compared to the older drivers, younger drivers (