March 25, 2007
Brain Limits Ability To Multitask Interruptions

A New York Times article reports on lots of recent research which demonstrates human minds become much less efficient when multi-tasking.

Several research reports, both recently published and not yet published, provide evidence of the limits of multitasking. The findings, according to neuroscientists, psychologists and management professors, suggest that many people would be wise to curb their multitasking behavior when working in an office, studying or driving a car.

These experts have some basic advice. Check e-mail messages once an hour, at most. Listening to soothing background music while studying may improve concentration. But other distractions most songs with lyrics, instant messaging, television shows hamper performance. Driving while talking on a cellphone, even with a hands-free headset, is a bad idea.

I've yet to get a cell phone in large part because I view it as an automated interrupt generator device. Ditto for a Blackberry. I sometimes wear earplugs at work so as to avoid hearing conversations. I need concentration time to get real work done. Oh, and voice mail? Why give someone a place to record a message to tell you something that they'll just repeat once they finally get ahold of you? I know people who do exactly that. They are driven by a deep instinctive need to communicate and be heard.

What I want: An automated device that will take spoken language in an email or a conversation and turn it into text. One can read text in less time than it takes to listen to a slow voice mail or, for that matter, a slow person in a meeting. What, you mean zone out on what someone is saying and then read the transcript? Yes, exactly. Besides, such a device could provide a useful history of what got said and agreed to in a meeting.

Younger people lose their brain speed advantage when interrupted.

Recently completed research at the Institute for the Future of the Mind at Oxford University suggests the popular perception is open to question. A group of 18- to 21-year-olds and a group of 35- to 39-year-olds were given 90 seconds to translate images into numbers, using a simple code.

The younger group did 10 percent better when not interrupted. But when both groups were interrupted by a phone call, a cellphone short-text message or an instant message, the older group matched the younger group in speed and accuracy.

How much productivity is lost by instant messaging and cell phone conversations? I watch people all the time fielding calls in office settings from someone who would not otherwise be calling them if the caller just didn't have a cellphone. The vast bulk of such conversations (at least from the side I hear) could have happened much later or never at all.

At Microsoft each interrupt costs an extra 15 minutes for a full return to work after the interrupt completed.

In a recent study, a group of Microsoft workers took, on average, 15 minutes to return to serious mental tasks, like writing reports or computer code, after responding to incoming e-mail or instant messages. They strayed off to reply to other messages or browse news, sports or entertainment Web sites.

I was surprised by how easily people were distracted and how long it took them to get back to the task, said Eric Horvitz, a Microsoft research scientist and co-author, with Shamsi Iqbal of the University of Illinois, of a paper on the study that will be presented next month.

Years ago (15 or 20?) Tom DeMarco and Anthony Lister published a book called Peopleware arguing that workplace interruptions cost each computer programmer a substantial amount of time (I faintly recall 30 minutes) per interruption. They based this on consulting work they'd done in companies where they did test of programmer coding speed combined with having programmers keep logs of every time they got interrupted. In DeMarco and Lister's experience some companies generated so many interruptions (e.g. phone calls, nearby conversations, intercom announcements) that in the course of a normal workday the programmers had 0 hours of useful work time.

Interrupts are bad. A study based on surveys and interviews with office workers put the cost of interrupts at $650 billion per year.

The productivity lost by overtaxed multitaskers cannot be measured precisely, but it is probably a lot. Jonathan B. Spira, chief analyst at Basex, a business-research firm, estimates the cost of interruptions to the American economy at nearly $650 billion a year.

That's a lot of potatoes.

What we need: Multiple phone numbers (or perhaps an extra digit on each phone number) with priorities on each cell phone. Let the callers send a priority signal for a call. If you are busy you could ignore priority levels below 1 or below 2. For example, parents could tell their kids to use 1 when a matter of life and death and 2 when they are stuck somewhere and so on.

We also need more structure in communications so that responses get caught and put into categories and fields. Also, I really want to be able to send an email with a marker that says "Bring this email back to my attention if it does not produce a response from the first 3 people on the To: list in N days.". Make it so that one can more easily track whether tasks are getting done and answers getting generated.

Also see my previous posts Brains Can Not Process Two Tasks In Parallel and Human Brains Limited Parallel Processing Capabilities.

Share |      Randall Parker, 2007 March 25 01:37 PM  Brain Limits

Gary Olsen said at March 25, 2007 6:15 PM:

Most people overestimate their own ability to keep track of multiple threads of activity.

Torr Noretranders covered this pretty well several years ago under the heading "bandwidth of consciousness" in "The User Illusion." Interesting book.

dave tweed said at March 26, 2007 8:08 AM:

On a slightly tangential note, this study discusses the "switch back to concentrating" time as one of the factors affecting multitasking.

I tend, partly because of having a work email address that's used only for work, to not get that much email on it during the day. (Also the fact that people know that if they send me pointless looking email I probably won't read it, let alone respond helps.) One thing I've noticed that has made a slight but noticeable dent in my workday concentration over recent years is moving to webmail. Previously on unix you could set an xbiff (small icon that changes colour when you've got new, unread mail for non unix people) in some corner of all your desktops. However, all the newer mail services I've encountered want you to use webmail (and don't provide documentation for anything else). Given that I park my web-browser on a non-visible desktop when working, whenever I'm waiting for an important email (asking a remote collaborator about an api point, etc) I find myself switching to check that my mail every half hour. Once the browser window is actually up, I give in to temptation and things go downhill...

I wonder if part of the reason for this is that webmail designers/programmers always have the browser visible in their "proper work", so never end up thinking of it as a "tempting cookie jar" you want out sight most of the time. If web-based apps like word-processors, etc, ever take off in big way, it'll be interesting to see if they have any productivity implications.

rsilvetz said at March 26, 2007 12:41 PM:

Actually, while I agree with the conclusions, part of it has to do with the study method. This was a left-brain dominant conscious-induced task activity.

Right-brain timeless tasks do not suffer interruption in the same manner. This is familiar to advanced aikidoists and athletes in the zone. The simulflow, for lack of a better term, is seamless. Driving is a multi-factorial experience that goes right-brain all the time. It takes major interruption to blow back to left-brain immediate mode.

Just a thought...

Mike said at March 26, 2007 2:16 PM:

Here is a site that promises to do what you ask. I signed up for a free trial, but did not receive a response until three weeks later. I can't vouch for it at all, I just know it exists.

Mthson said at March 27, 2007 5:26 AM:

re: "whenever I'm waiting for an important email ... I find myself switching to check that my mail"

I believe most major webmail providers can alert you with the authors of new email when it arrives: MSN messenger for Hotmail etc.

Lono said at March 27, 2007 9:18 AM:

I find cell phones are great - as long as I only turn them on when I need to make an outgoing call.

I also use that opportunity to check for voicemail, missed calls, etc - as I am at that time away from my technical tasks.

I firmly believe that the world governments enjoy the passifying/distracting effect of multitasking more than they dislike the lost productivity.

I would not discount that some businesses have also found this effect to be useful in lowering turnover and worker dissatisfaction.

I, personally find it disgusting how uniformed the Average American has become - particularly in this age of ubiquitous internet access, but I am sure it is do to this multitasking effect.

I recall my peers in elementary school being far more reflective and decisive than my adult contemporaries.

Of course I do not discount the effect that television has also had in this sad situation.

Bob Badour said at March 30, 2007 3:43 PM:
That's a lot of potatoes.

Recently, local farmers were getting $0.02/lb for potatoes, which makes $650billion more than 32 trillion pounds of potatoes, in fact. Even at the year-to-year norm of $0.08/lb, that's over 8 trillion pounds.

Yep, that's a lot of potatoes!

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