Abstract:

With the development of communication technology and popularization of smart phones, pedestrians using cell phones while crossing road have become more prevalent. It is estimated to account for nearly 20% of all pedestrians in both observations and self-report surveys. Consistently, the proportion of pedestrian casualties involving mobile phones during road crossing keeps increasing. This study reviewed 34 papers to evaluate how using a cell phone affected their safety and efficiency in road crossing. We also highlighted some mechanisms in terms of human information processing from scene perception, decision making to movement control.
Overall, the evaluation shows detrimental effect of using cell phone on both safety and efficiency in crossing a road. Compared with non-distracted pedestrians, pedestrians using a cellphone are exposed to higher risk as indicated by more conflicts with vehicles, higher likelihood of violations such as going against red light and crossing outside of crosswalks, and less vigilance behaviors such as looking at vehicles. In virtual environments, they also had more collisions with vehicles or near misses where the safety margin is so small that the vehicle almost collides with the pedestrians. In terms of efficiency, pedestrians distracted by cell phones usually waited longer before starting to cross. What’s more, they are more likely to deviate from a straight route and have a lower walking speed. Consequently, their overall efficiency in road crossing declined.
The above decline in safety and efficiency results from impairments in earlier processes of information processing. First, during the scene perception phase, distracted pedestrians tend to have a narrower scope of attention (esp. in the peripheral visual field), making it more difficult to perceive visual and auditory cues in traffic scenes. What’s worse, the distraction from a channel (visual or audial) can not only affect scene perception of the same channel, but also affect other channels by occupying central cognitive resources. Second, during the decision-making phase, distracted pedestrians are also more likely to miss street crossing opportunities when the gap between vehicles are large enough to cross or make risky decisions when the gap between the vehicle are too small to cross. Finally, using a cell phone also harms pedestrian movement control ability. Their gait patterns are more conservative with less frequent stepping and alternation between the two feet, shorter stride, and larger lateral deviation of feet movements. Besides, their action stability declined as a result of trying to reduce the relative movement of cellphones and head while browsing messages from cell phones.
The above impairments of information processing are modulated by specific task types (e.g. conversing vs. browsing), pedestrian age and experience in cell phone usage. To integrate these findings within a framework, a conceptual model was proposed to describe the effect of mobile phone distraction on pedestrians’ information processing and behavior based on previous pedestrian cognitive models. Based on the model, we highlighted several gaps for future research. In the scene perception phase, future research needs to evaluate how mobile phone distraction affects pedestrian auditory scene perception, which is important to locate risky targets in traffic scenes. During the decision-making phase, efforts are still needed to evaluate how using a cell phone impacts the sub processes within the gap acceptance decision-making, such as estimation of vehicles’ time to arrival and pedestrians’ needed time to cross a road. The evaluation will help to develop targeted interventions to improve pedestrian safety while using cell phones.

Key words: information processing, distraction, mobile phones, pedestrian, transportation safety