I keep hearing about how great multitasking is; lots of people seem to be constantly texting, (even while driving/walking), checking email every five minutes and juggling seven different to-do lists at the same time. It's a neat trick of you can manage it, and you certainly look busy , but do you actually get much done.
As notorious single-tasker (a characteristic shared by many programmers), I have long held an unreasonable disdain for the alleged benefits of mutitasking and at last there is evidence to support me.
A study from Stanford University presented to the USA National Academy of Sciences [PNAS] shows that habitual multitaskers perform worse at all types of tasks - not just when they're multitasking, but always.
Vindicated at last!
It's not the most comprehensive study imaginable (100 subjects, four different task types), but given that it started with an expectation of finding where (not if) multitaskers performed better, I don't see any reason to dispute the basic findings. As always 'more research is needed'.
[PNAS] Proceedings of the National Academy of Sciences Cognitive control in media multitaskers
[Stanford] Standford University News Media multitaskers pay mental price, Stanford study shows
[PT] Psychology Today The Madness of Multitasking (includes references to some additional reports)