You’ve seen this person. Maybe you’ve even been this person. We’re talking about someone shuffling along a sidewalk or through a shopping mall, so entranced by the phone in their hands that they bump into people or almost get run over. Yes, this behavior can be annoying. Now we have scientific evidence it can be dangerous. A new study has found that people who type or read on their phones while walking are less likely to look at their surroundings, keep their balance or walk in a straight line. This may seem obvious to anyone who has been jostled by an oblivious text messager. But researchers at Australia’s University of Queensland say theirs is the first study to measure how typing text on a cellphone impacts “gait performance” and kinematics, or the study of body motion. “Texting, and to a lesser extent reading, on your mobile phone affects your ability to walk and balance,” said Siobhan M. Schabrun, an honorary senior fellow at the University of Queensland and the lead author of the study. “This may impact the safety of people who text and walk at the same time.” The perils of texting while driving are well documented. But texting while walking has its own pitfalls. In January 2011 a woman fell headlong into a fountain at a Pennsylvania mall while tapping on her phone, a blunder that was captured by a security camera and was widely mocked on YouTube. Last October an Illinois man was struck by a car while texting on his phone and walking in the middle of a highway (authorities said he also was drinking at the time). And a nationwide study by Ohio State University last year found that the number of pedestrians treated in U.S. emergency rooms for injuries related to phone use while walking has more than doubled since 2005. In the new Australian study, scientists studied the effect of phone use while walking in 26 healthy people. Each person walked in a line over a distance of about 28 feet while doing one of three tasks: walking without the use of a phone, reading text on a phone, or typing the sentence, “the quick brown fox jumps over the lazy dog.” Their bodies’ movements were evaluated using a three-dimensional movement analysis system. Researchers found that texting, and to a lesser extent reading, affected movements while walking. When participants were texting, they walked more slowly, deviated more from a straight line and moved their neck less than when reading on their phones. The study was published Wednesday in PLOS ONE, a peer-reviewed online journal that publishes reports on primary research from a variety of scientific disciplines.