Nicholas Carr's latest, erudite work The Shallows: What the Internet is Doing to Our Brains is well worth reading. In particular, I would recommend the chapter "The Juggler's Brain" which does an excellent job of compiling and refuting such notions as multi-tasking. He refutes well the contention of Everything Bad Is Good for You (Johnson, 2005). With connections to work on working memory (cf. Alloway, Tracy) and suggestions as to how technology, when not used with circumspection, can change our ability to think, while suggesting that the internet could be related, too, to ADHD, some LDs etc. A great read.