The range of visual detection of ground-level cues during distracted walking: Effect of cue contrast and walking speed.

Walking while distracted by a smartphone has been a major safety concern for pedestrians. Visual and cognitive attention paid to the smartphone while walking with the head tilted downward would affect the ability to perceive walkway hazards and elevate risks for pedestrian accidents associated with physical contact with obstacles. A laboratory experiment was conducted to evaluate the performance of detecting ground-level visual cues during texting while walking. Forty young smartphone users performed walking trials at faster, preferred, and slower speeds for the dual-task walking on a treadmill and detected approaching cues of three contrast levels. Detection distance was quantified from the location of cue detection to the participants to assess the effects of walking speed and cue contrast on detection performance. Results show that detection distance varied from 1.7 m to 2.9 m for Low to High contrast cues and from 2.3 m to 2.5 m for Slower to Faster walking speeds, and the effects of contrast and speed were statistically significant (p < 0.05). Study findings suggest that higher contrast fixtures or in-ground signals and slower walking would help smartphone users perceive walkway hazards and in-ground safety signals earlier during their distracted walking.