In another test, students were asked whether they were seeing an even or odd number or a vowel or a consonant when shown a letter and a number simultaneously. A prompt asked students to answer either the letter question or the number question.
Frequent multi-taskers took longer to answer than lighter multi-taskers, indicating they had a more difficult time switching between numbers-based and letters-based tasks.
"This was shocking," Ophir said. "You'd think multi-taskers would be better at task-switching, but they were slower."
The reasons for the decreased cognitive control are unclear, Ophir said. Researchers cannot say if the multi-tasking itself damages cognitive control -- and if so, how much multi-tasking it takes for damage to occur -- or if those who tend to multi-task with media have less cognitive control to begin with.
"Either way, the prescription is to multi-task less," Ophir said. "The big take-away from me is to try to build periods of focus, to create times you are really focused on one thing."
Media multi-tasking includes doing one or more activities at once, including e-mailing, surfing the Web, writing on a computer, watching TV, texting, playing video games, listening to music or talking on the phone.
"It seems from our survey that everybody is doing some amount of multi-tasking," Ophir said. "It's hard to find people that don't multi-task. But it's all about intensity."
The findings have implications for today's universities and workplaces, where multi-tasking has become the norm, said Dr. John Lucas, a clinical assistant professor of psychiatry at Weill-Cornell Medical College.
"There is no free lunch in switching from one task to another," Lucas said. "People multi-task without an awareness that transitioning from one set of responsibilities to another involves some lag time, and when
All rights reserved