It's not uncommon in a New York City subway car, an airport terminal or just about any other public space to see a dozen or more people completely consumed by what's happening on the screen of their smartphone, to the exclusion of the world around them.

Despite their power to connect, smartphones are also used to disconnect their owners. Thirty percent of 18- to 29-year-olds surveyed in a Pew Research Center study (pdf) released earlier this week said they pretended to be using their phone in order to avoid interacting with the people around them.

Even when they're not calling, texting or surfing the Web, smartphone users (more than one third of American adults these days) immerse themselves in online video games such as Angry Birds, Solitaire and FarmVille. Or they watch movies, one of the reasons handset makers LG Electronics and HTC have launched mobile phones in Taiwan with glasses-free 3D screens.

Smartphones and even plain old cell phones obviously are popular as well for quick information retrieval (so much so that their absence can cause panic attacks among some users). In fact, half of the 2,277 mobile phone owners surveyed had used their phone at least once during the survey period—April 26 to May 22, 2011—to get information they needed right away, according to Aaron Smith, the Pew senior research specialist who led the study.

Forty percent of mobile phone owners reported finding themselves in an emergency situation in which having their phone with them helped. More than one quarter admitted having experienced a situation during that month in which they had trouble performing some task because they did not have their phone with them. And 42 percent admitted to using their handset simply to stave off boredom.

Another indicator of how indispensable mobile phones have become: Amazon CEO Jeff Bezos and company VP Greg Hart earlier this year filed a patent for ways of protecting handsets from damage when dropped or otherwise impacted. The patent covers, among other things, an airbag deployable from a side of the portable device if impact is imminent.

Image courtesy of Justin Horrocks, via iStockphoto.com