From the Law Librarian Blog, “A series of tests show that people who multitask the most have a hard time concentrating and avoiding distractions compared to those multitasking the least. . . . Multitaskers consistently had performance problems when tested. I'd tell you more but I can't remember much about it having checked my three email accounts for the 30th time in the last five hours. Luckily I can remember where the citation is from. Read about it in Wired, here."
The original study is, “Cognitive control in media multitaskers.” By Eyal Ophira, Clifford Nass, and Anthony D. Wagner. Proceedings of the National Academy of Sciences, Vol. 106 No. 33, August 25, 2009.