In most jobs, one needs to be able to switch quickly between tasks, but this is easier said than done. Thought processes from the first task are hard to shut off - “attention residue,” in the words of the author of a new study - and can interfere with the second task. Not only can attention residue impede performance on the second task, but attempting to make the transition when the first task is unfinished - or when the first task did not have a tight deadline - makes the problem worse. The only transition that didn’t suffer from attention residue was when the person believed that the first task had been finished under deadline pressure. In other words, put yourself and your co-workers under the gun, do one task at a time, and then move on.

via Uncommon knowledge: When friends make you poorer - The Boston Globe.