Information overload!!!

There's yet another article on information overload, this time in the WSJ online. This one starts out with this sober warning:

Warning: On average, knowledge workers change activities every three minutes, usually because they're distracted by email or a phone call. It then takes almost half an hour to get back to the task once attention is lost. So if you're trying to read this column at the office or within range of your mobile device, what should be a few minutes can take much longer. Consider the rest of this article an 800-word test of your ability to maintain attention.

Okay, I'm having trouble parsing this. The casual reader might think that this means that once you get distracted, it takes 30 minutes to focus again. But if you're changing activities every three minutes, that means that in that 30-minute span you're cycling through ten activities. Right? So what is this business about "the task"? How are tasks defined? Does this string of ten activities represent several steps in a larger activity (like the Communication Event Models that Bill Hart-Davidson creates from studying knowledge workers)? Does it represent touching several different genres in a genre ecology, which collectively coordinate and mediate a larger work activity? Unfortunately we don't get any answers in the loose string of personal anecdotes that make up the bulk of this article.