Cognitively Demanding Object Negotiation While Walking and Texting.

Cell phone related pedestrian injuries are increasing, but the underlying causes remain unclear. Here, we studied how cell phone use directly affected obstacle avoidance ability. Thirty healthy adults participated. Cognitive capacity was quantified using standard tests. Participants walked on a treadmill in a virtual reality environment with and without performing a texting-like cell phone task. Participants also navigated either 'no', 'simple' or 'complex' object negotiation tasks that directly manipulated the cognitive complexity of this object negotiation task. Cell phone use led to more collisions, delayed responses, and increased variability of responses when navigating objects. Mean object avoidance responses were further delayed for the cognitively more complex object negotiation task. Individuals' baseline attentional capacity inversely predicted the number of object collisions when participants used the cell phone. Individuals with higher cognitive flexibility (i.e., better ability to switch between tasks) performed better on the cell phone task when they had to negotiate obstacles. Importantly, cognitive ability predicted performance only when both tasks (texting and negotiating objects) were being performed. Thus, using a cell phone while walking introduces a visual distraction that impairs healthy adults' ability to respond to cognitively demanding object negotiation tasks in their environment.