I used to multitask a lot when I was a waiter. I wasn't able to do the task as well when I focus my mind on one of them at a time. I would forget a customer's drink or didn't do a good job of cleaning up the table or forgot what's the to go order. Good thing those people are nice about it
I notice a lot of the time, people who talks on the phone while driving tend to drive very slower than the ones who didn't. The speed limit is 35, they'd drive 30, whereas the traffic of non-phone-talkers are all 40 miles + I wish they'd stop doing that...many a times did I get close calls with those people...