Using a smartphone while walking: The cost of smartphone-addiction proneness

•Using a smartphone while walking increased decreased walking-performance.•Higher smartphone-addiction proneness lead to higher number of missed stimuli across all experimental conditions.•Emotional arousal mediated the relationship between the experimental conditions and the number of missed stimuli.•Emotional arousal also mediated the relationship between the experimental conditions and accuracy.•The gaming condition was the most distracting smartphone task performed.