"I've been busy all day, so I must have got a lot done"

At ten past five you were tired, and tiredness normally means work was done. You answered perhaps sixty messages and touched a dozen tasks. It seems impossible that such a day produced nothing. So you conclude that it must have produced a lot, and that the report's lack of progress is a puzzle, or bad luck, or somebody else's fault.

There are two separate things here, how busy you were and what you got done. They feel like the same thing, and they aren't.

Gloria Mark, Daniela Gudith and Ulrich Klocke ran an experiment in which people did an office task, some with interruptions and some without. The interrupted people finished the task in less time, with no loss of quality. They did it by working faster. They also reported more stress, more frustration, more time pressure and more effort. People who are interrupted speed up to compensate, and the speeding up is tiring. So the tiredness at ten past five is real. A good part of it came from the switching and wouldn't have been there on a day of steady work.

A second study explains why the juggling day feels good while it's happening. Zheng Wang and John Tchernev had students report their activities, needs and satisfactions over four weeks. The students often multitasked for practical reasons, to get more done or learn more. Multitasking didn't satisfy those practical needs. What it did deliver was emotional satisfaction, which the students hadn't been seeking. The researchers suggest this is why the habit persists. You juggle in order to get more done, you get less done, and you feel good about it anyway, so you do it again.

That matches the experience. Each small completion pays a little. You send a reply, clear a notification, or answer a colleague's question. None of them is the report. But there are sixty of them in a day, and together they produce a steady sense of getting through things. The report pays nothing until it's finished, and on a juggled day it never is.

So the feeling isn't a reliable measure, and you need a better one. At the end of each day, write down what you finished. It has to be completed and gone, sent or filed or handed over. "Worked on the report" doesn't count. "Sent section two to Priya for comment" does. A day's list might have three things on it, or none, and either way it's an honest record. Most people who try this find that the list is a shock for the first week. It's also the quickest way I know to change the habit, because it measures output, which the habit has been neglecting.