Exercise scientist Conrad Earnest was dodging some oblivious pedestrians in England when inspiration struck. He was trying to walk down the sidewalk, but all around him people were weaving back and forth as they focused on their smartphone screens. Earnest suggested to two of his students that they study the dangers of texting while walking. Specifically, they could ask whether texters are more likely to trip and fall—perhaps wishful thinking on Earnest's part as he walked among them. The two University of Bath undergrads, Robynne Smith and Sammy Licence, dove into the project. A recent study by other researchers had looked at people who were texting while walking in a straight line. But for this study, they'd try to provide a challenge that was closer to a real-world sidewalk. Subjects would walk an obstacle course that included stairs, a curb, and even fake pedestrians. The researchers recruited 30 subjects who ranged from 18 to 50 years old. First they familiarized their subjects with the obstacle course. Subjects would make a big zigzag around a room. On the way they would have to step over a "curb," walk along a slightly raised platform, go up two steps, and pass between a pair of soccer dummies (below, in blue). Reflective markers stuck on subjects' sneakers and waistlines let the researchers track their steps with 3D motion-capture cameras. Everyone completed the course three times. They walked it once with no distractions. Another time, they walked it while responding to a standardized set of text messages on their own phones. And in case that wasn't hard enough, they walked the course while using their phones to answer a mental math quiz. Whether subjects were simply texting or doing onscreen math problems, the results were the same. People on their phones were roughly 25 percent slower to finish the course. While they tapped away on their screens, subjects also took shorter, more frequent strides. They spent longer navigating the stairs. And they took higher, more cautious steps over obstacles. Overall, the researchers called this a "more conservative locomotion strategy." Earnest is now at Texas A&M University. Despite his initial hypothesis—or hope—people didn't seem any more likely to trip and fall while on their phones. The researchers measured this by counting how many times subjects bumped into obstacles. There was no difference between texters and non-texters, suggesting that the "conservative" strategy was working. The researchers also failed to see people weaving on their zigzag course. Still, Earnest wishes people would knock it off. If your text message or email really can't wait, he suggests, how about pulling over? That way you won't slow down and get in everyone's way. On the other hand, if you wipe out, there are some scientists who may be eager to study you.
Image: top by Simon Birch (via Flickr); bottom courtesy of Conrad Earnest.
Licence S, Smith R, McGuigan MP, & Earnest CP (2015). Gait Pattern Alterations during Walking, Texting and Walking and Texting during Cognitively Distractive Tasks while Negotiating Common Pedestrian Obstacles. PloS one, 10 (7) PMID: 26222430