"In one recent study, Russell Poldrack, a psychology professor at the University of California, Los Angeles, found that “multitasking adversely affects how you learn. Even if you learn while multitasking, that learning is less flexible and more specialized, so you cannot retrieve the information as easily.”
The Kaiser report noted several factors that increase the likelihood of media multitasking,
“In this media-heavy world, it is likely that brains that are more adept at media multitasking will be passed along and these changes will be naturally selected,” the report states. “After all, information is power, and if one can process more information all at once, perhaps one can be more powerful.”

and .. sometimes more is less ....