Because in our multi-tasking life, we keep using the standards of mono-tasking for everything we do. Casey Schwartz reviews Cathy Davidson's Now You See It: How the Brain Science of Attention Will Transform the Way We Live, Work, and Learn:
We've been trained to assume that working hard means focusing on a single task to completion, then doing it again. But, says Davidson, "the new workplace requires different forms of attention than the workplace we were trained for."
The result is that we feel anxious and guilty, convinced we’re not getting enough done, not achieving an honest day’s work, failing to live up to the iconic model of our hard-working, brick-and-mortar grandparents. As Davidson puts it, "We’ve inherited a sense of efficiency modeled on attention that is never pulled off track."
But these days, according to research, "the contemporary worker switches tasks an average of once every three minutes."
The Dish 