It’s been proven time and again (and a million times in my personal experience – just ask my spouse!), that you can only focus on a single thing at a time. This is why interruption technology like Slack is dangerous to your business.
People have told me, “I can focus on more than one thing at a time.” This is certifiably false, unless they have a natural talent for this sort of thing (for example, Bill Clinton could play bridge, hold a conversation about international policy, and do a crossword puzzle at the same time). Maybe they can give attention to more than 1 thing at a time (every parent can attest to this fact), but not focus.
Check out this article by Matt Richtel explaining how the military has adjusted to this reality, and how businesses can become more profitable by accepting this premise.
What has your experience been with attention and focus?