Article: Divided Attention (classroom multitasking)
Published in The Chronicle of Higher Education, January 31, 2010
A worthwhile read citing both studies and anecdotal evidence from college professors about the lowered comprehension, test performance and reasoning capabilities of students who multi-task while in class.
"Heavy multitaskers are often extremely confident in their abilities," says Clifford I. Nass, a professor of psychology at Stanford University. "But there's evidence that those people are actually worse at multitasking than most people."
Several specific procedures for testing the brain's capacity and effectiveness at juggling several tasks simultaneously, including simple classroom demonstrations of counting and reciting the alphabet, are described in the article.
Found this article via the Mind Hacks blog.