In New York, when people are texting while walking in front of me, I'm frequently overcome by rage. But since throwing people into the street is "assault" according to "the law," I abstain. However, people--come on.
In this study published in the online journal PLOS One, researchers used motion-capture software to assess the gaits of 26 healthy folks, with and without cellphone use. Here's the setup:
Individuals walked at a comfortable pace in a straight line over a distance of ~8.5 m while; 1) walking without the use of a phone, 2) reading text on a mobile phone, or 3) typing text on a mobile phone. Gait performance was evaluated using a three-dimensional movement analysis system. [Ed note: awesome.]
Eight cameras were set up to monitor the people walking while reading or texting (the phrase, sent on your standard QWERTY virtual keyboard, was "the quick brown fox jumps over the lazy dog"). No surprise, the people reading or texting were slower, deviated from a straight line more, and on top of everything, didn't text very accurately. (_The quikj bbrown fox jumpd _etc. etc.)
Evaluation of gait performance revealed that individuals walk slower, demonstrate greater absolute medial-lateral step deviation, increase rotation ROM of the head with respect to the global reference frame, walk with a flexed head position, reduce neck ROM, and move the thorax and head more in-phase with reduced phase variability, during texting and reading than unconstrained walking.
In short, reading a text or typing one while walking makes you dumb. It likely increases your chances of injury, the researchers suggest, and that's even without factoring in the injury your fellow pedestrians may give you.