One thing at a time, please

4th December, 2010

I just splashed out on a new widescreen monitor, which I have rotated and set alongside the near-identical widescreen monitor I already own. Now I have two tall screen monitors, side by side, and I feel like the operator of a nuclear power station.

Publilius Syrus, a Roman slave with a knack for writing maxims, observed that “to do two things at once is to do neither”. Presumably he would not have approved of the twin-monitor arrangement, had he had the faintest idea what a twin monitor was.

Poor old Publilius would have gone into conniptions if he’d seen what today’s teenagers get up to: watching television while sitting with a laptop, surfing the web, sending text messages and instant messages, and listening to music. No wonder so many commentators are concerned about our growing addiction to multitasking.

I have some sympathy. When I indulged, for the first time, in “live-tweeting” one of the leaders’ election debates in April (I’m @timharford on Twitter, by the way: follow me if you’d like to see my Publilius Syrus impersonation) I discovered something striking: while I had fun commenting and reading the comments of others, I later had very little recollection of what any of the three potential prime ministers had actually said. This is worth bearing in mind: I now strongly suspect that anybody who claims to be commenting live from any event is unlikely to remember much about what happened.

Researchers who study multitasking wouldn’t be surprised. In 2006 Karin Foerde, Barbara J. Knowlton and Russell A. Poldrack, then psychologists at the University of California, Los Angeles, showed 14 people various shapes flashing on a computer screen while playing them low and high tones. In some experimental runs the subjects were asked simply to make predictions based on recognising patterns in the shapes; in other runs they also had to count the number of high tones.

The result was fascinating: on the multitasking runs, people were perfectly good at making predictions on the fly, but couldn’t then explain the underlying patterns, or apply them flexibly in other contexts. The technical term for this is that their “declarative learning” was stunted by the distraction. In short, multitaskers seem competent at the time but may not be taking much away from their experiences.

I try hard not to make that mistake. Even the twin monitors are designed so that while I’m reading a research paper on screen, this column stays in view.

But I am guilty of an entirely different form of multitasking: in any given month, I have lots of projects on the go. This feels a world away from distracting myself with instant messaging. In fact it feels symptomatic of being a grown-up in the 21st century. But perhaps it, too, is unhelpful.

The psychologists’ lab isn’t well-suited to testing that hypothesis, but there is a new working paper from three economists, Decio Coviello, Andrea Ichino and Nicola Persico. They studied the caseload of 31 judges in a specialised court in Milan, who over five years dealt with over 58,000 cases. Because of the way cases are randomly assigned, and a rule stating that cases must open no later than 60 days after assignment, some judges find themselves with many more cases open at the same time. Coviello and his colleagues find that judges who have been obliged to work on many cases in parallel take longer to complete similar portfolios of cases. One implication is that the 60-day rule probably slows the average case down rather than speeding it up.

The message for the rest of us is that Publilius Syrus was right about multitasking. One thing at a time is best. The exception, I suppose, is if you’d rather not remember what you’re supposed to be doing. No wonder so many of us check our BlackBerries in meetings.

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