As it is simply impossible for the human brain to multi-task, it's a hindrance. It wastes the time of the rest of the team.
Even a computer can't multi-task. The computer is much more efficient at switching tasks from window to window so it appears to be multi-tasking but it's not.
A brain however cannot pay attention to two things requiring thought processing or learning functionality. Can't be done. Actually over time, it will do irreparable damage to the human brain.
Stop kidding yourself and get in the game. You're at the meeting for a reason, or you should have declined the meeting if it is not the best use of your time. You own it to your employer if not to yourself. Saving Changes...
I take it as an opportunity to coach them on the evils of unhealthy multitasking. There are a number of great team games which can be used to educate the whole team on that.
For agile teams, I'd also suggest that avoiding multitasking is a good working agreement...
I like this. A working agreement should include things to show respect for other and their time.
In a meeting or conversation, saying "I'm sorry. what was it you wanted to know now that you've specifically addressed me?" is not respectful of others. It says listening to you talk is beneath my importance.
Good item to add to my next working agreement! Saving Changes...