Researchers from the University of Missouri wanted to know how subjects behaved when parted from their iPhones, so they recruited 208 students for a survey on "media usage." The researchers used the survey to screen for iPhone users and eventually recruited a group of 41 respondents for an experiment in cell phone separation anxiety. During the study, participants were placed in a cubicle and asked to perform word search puzzles. Researchers monitored their anxiety levels, heart rate, and blood pressure while the subjects had their iPhones with them.

Then, the real experiment began. Researchers told participants that their iPhones were causing interference with the blood pressure cuff and asked them to move their phones. The phones were placed in a nearby cubicle close by. Next, the researchers called the subjects' phones while they were working on the puzzle. Immediately afterwards, they collected the same data.

The results changed dramatically. Not only did the participants' puzzle performance decline significantly while the phones were off-limits, but their anxiety levels, blood pressure and heart rates skyrocketed. One of the researchers concluded, "iPhones are capable of becoming an extension of selves such as that when separated, we experience a lessing of 'self' and a negative physiological state."