The Case Against Multitasking

For years, being able to do several things at once was seen as a sign of competence. Job advertisements asked for "excellent multitaskers", and people boasted about answering emails during meetings. That reputation has now largely collapsed, and the research behind the collapse is worth understanding. The first thing to say is that true multitasking barely exists. The brain cannot focus on two demanding tasks at the same time; what it actually does is switch rapidly between them. Every switch has a cost. Studies at Stanford and elsewhere have shown that people who had been switching between tasks made more mistakes, took longer to finish, and remembered less of what they had done than people who completed the same tasks one after another. Heavy multitaskers were, if anything, worse at filtering out irrelevant information than light ones — the opposite of what they believed about themselves. Why, then, does it feel so productive? Partly because switching provides a small hit of novelty each time, and novelty feels like progress. Partly because the cost is invisible: nobody notices the ten minutes it took to get back into a report after a two-minute chat, because those minutes are spread across the whole afternoon. The second problem is deeper. Work that requires real thought — writing, analysis, learning something difficult — depends on holding a lot of information in mind at once. If that information is repeatedly dropped and rebuilt, the quality of the thinking suffers even when the task eventually gets done. None of this means that variety is bad. Alternating between different kinds of work over a day is healthy. The damage comes from interruption during a task, not from changing tasks between them. The practical advice is therefore simple, if unfashionable: decide what you are going to do, close everything else, and do it. If it had been easy, of course, nobody would have needed the research.