You may have mastered walking and chewing gum, but you should reconsider adding texting and cellphone conversations to your ambulatory repertoire, a new study warns.


Scientists at Stony Brook University in New York have found that using a cellphone to talk or text while walking can disrupt your gait to such a degree as to cause accidents.


The study, published in the current issue of the journal Gait & Posture, is the first to focus on the basic mechanics of putting one foot in front of the other while using a cellphone, as opposed to research on unexpected physical dangers, such as walking into a car or down a manhole.


Hang up and walk?

The researchers, Eric Lamberg and Lisa Muratori of Stony Brook's School of Health Technology and Management, recruited 33 male and female adults in their 20s who, in theory, had been perfecting the art of walking and talking for at least 20 years. Being in their 20s, the subjects also were quite skilled at using cellphones.


As a baseline test to assess walking skills, the subjects were asked first to spot a target about 30 feet (9 meters) away and then, while wearing a hood that blocked much of their vision, to walk to that target. The researchers measured the subjects' gaits and other elements of walking as the participants tried the test three times.


Although their vision was shielded so that they couldn't see the floor or target, all the subjects could walk straight to the target, relying on a brain function called working memory.


The subjects came back in a week to try the test again. This time, one group repeated the exact same test, with a hood; one group did it with the hood while talking on a cellphone; and one group did it with the hood while texting, able to see the cellphone clearly.


The cellphone activity clearly interfered with the subjects' working memory, the researchers said. The control group (with the hood and no cellphone) performed the test as easily as in the week prior. Those in the talker group could still walk somewhat straight but were slower compared with the previous week, by 16 percent on average. Those in the texting group, however, veered off course by several feet, or by 61 percent, and walked 33 percent more slowly.


Calling the brain; Come in, brain

Although the authors themselves describe the study as preliminary, they state in their report that the degree to which cellphone use alters gait in a simple, flat 10-yard path "may have significant real-world repercussions."


Beyond the obvious — that cellphones are distracting — the results imply that there is a greater cognitive effort involved in using a cellphone than the user might anticipate, the researchers said. This entails working memory and rudimentary cognitive processing, the ability to extract relevant spatial and temporal information from the environment.


That is, you may think you are sufficiently gazing up while texting, or looking ahead while talking, but your brain is not absorbing enough information to enable you to walk normally. This, in turn, may cause you to misjudge the distance to a curb or to not detect subtle changes in the texture or steepness of the surface you are walking on, which could result in a fall.


The same likely applies to walking and reading on a cellphone. Hmmm, maybe we should have mentioned that at the start of this article.


Christopher Wanjek is the author of the books "Bad Medicine" and "Food at Work." His column, Bad Medicine, appears regularly on LiveScience.


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