This great article on the subject of multitasking discusses whether it's actually possible to concentrate on more than one task at any given time. The conflict between being busy and being productive is obvious in every work environment and often the appearance of being busy is rewarded. After reading this, I'm going to make a conscious effort to prioritize tasks rather than multitasking and to reward productive behaviours.
Switching cost is the disruption in performance that we experience when we switch our attention from one task to another. A typical person checks email once every five minutes and that, on average, it takes 64 seconds to resume the previous task after checking your email.In other words, because of email alone we typically waste one out of every six minutes.