The Sluggish Multitasker
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Economics Strategy Apr 7, 2014

The Slug­gish Multitasker

Cog­ni­tive demands aside, mul­ti­task­ing can be inef­fi­cient and demoralizing

Based on the research of

Decio Coviello

Andrea Ichino

Nicola Persico

Sev­en open brows­er win­dows, a chim­ing smart phone, and an ongo­ing Skype call: these are the hall­marks of the mod­ern-day, mul­ti­task­ing employee. 

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Orga­ni­za­tions are becom­ing more com­plex and infor­ma­tion tech­nol­o­gy is becom­ing more preva­lent,” says Nico­la Per­si­co, a pro­fes­sor of man­age­r­i­al eco­nom­ics and deci­sion sci­ences at the Kel­logg School. As such, work­ers are often asked to do more in the same amount of time — a chal­lenge that invari­ably leads to doing more at the same time.

But should it? There are, of course, costs to such a strat­e­gy. The idea that work­ing on many things at the same time can actu­al­ly slow you down — it’s not a new idea,” says Per­si­co. In recent years espe­cial­ly, the down­sides of mul­ti­task­ing have been broad­cast far and wide. Don’t Mul­ti­task: Your Brain Will Thank You” warns an arti­cle in Time. Break the Mul­ti­task­ing Habit” encour­ages USA Today. Most of the warn­ings have focused on our lim­it­ed cog­ni­tive resources: we can only do so much at once before every­thing starts to suf­fer — and there are men­tal costs asso­ci­at­ed with piv­ot­ing between projects too.

But Per­si­co — along with Decio Coviel­lo of HEC Mon­tréal and Andrea Ichi­no of the Uni­ver­si­ty of Bologna—recent­ly built a math­e­mat­i­cal mod­el that offers anoth­er rea­son for the pro­duc­tiv­i­ty loss­es asso­ci­at­ed with mul­ti­task­ing. Men­tal costs aside, switch­ing back and forth between projects is fun­da­men­tal­ly inef­fi­cient. If there is val­ue in fin­ish­ing a project” — as opposed to mere­ly mak­ing progress — then the best thing you can do is to fin­ish one before you start the next one,” says Persico.

The Inef­fi­cien­cies Com­pound
Con­sid­er a sce­nario in which you have two projects, each of which requires a sol­id five days of work to com­plete. If you switch back and forth between the two tasks equal­ly, fin­ish­ing them on the same day, each project will take you an aver­age of two five-day work­weeks to com­plete. But if you ded­i­cate all of your time to one project before switch­ing to the oth­er, each project will take you, on aver­age, just a week and a half (a week for the first and two weeks for the second). 

Stack­ing projects back to back, in oth­er words, allows you to fin­ish one project much ear­li­er than you oth­er­wise would, and takes you no longer to com­plete the sec­ond. As the num­ber of projects increas­es, so do the effi­cien­cies gained by tack­ling them one by one.

If there is val­ue in fin­ish­ing a project” — as opposed to mere­ly mak­ing progress — then the best thing you can do is to fin­ish one before you start the next one,” says Persico.

The inef­fi­cien­cies, accord­ing to Persico’s mod­el, have the fur­ther effect of demo­ti­vat­ing work­ers. If I jug­gle more,” says Per­si­co, then it means that the rewards of my efforts are going to be more and more post­poned.” After all, a pay­check, or com­ple­tion bonus — or even just a pat on the back — does not mean as much when it is a month away as when it is just few days away.

Throw mul­ti­ple super­vi­sors into the equa­tion, and a prob­lem­at­ic sit­u­a­tion gets even worse. As a work­er,” says Per­si­co, you don’t real­ly choose what to work on in iso­la­tion. You do so under the pres­sure of oth­er peo­ple — maybe your cowork­ers, maybe your supe­ri­ors — and as this unco­or­di­nat­ed set of pres­sures takes place, then nat­u­ral­ly you will be dri­ven to multitask.”

If each of your super­vi­sors lob­bies you to work on her task first, you will be pushed to work on more projects simul­ta­ne­ous­ly than if left to your own devices. But the lob­by­ing becomes some­thing of a vicious cycle: as the num­ber of projects increas­es, so do the com­ple­tion times, which in turn increas­es the impor­tance of lob­by­ing efforts in the future.

A Note to Man­agers
In addi­tion to offer­ing employ­ees yet anoth­er rea­son to avoid mul­ti­task­ing, Persico’s research sug­gests poten­tial draw­backs to orga­ni­za­tion­al struc­tures in which a sin­gle work­er or group reports to mul­ti­ple super­vi­sors. There are plen­ty of rea­sons why an orga­ni­za­tion might be struc­tured this way, of course — indi­vid­ual divi­sions may not have the need for their own legal team, or HR depart­ment, for instance — but, says Per­si­co, I think you have to care­ful­ly con­sid­er the trade-offs.” Work­ers are left between a rock and a hard place” should one man­ag­er not observe (or care) how much a work­er is required to do for anoth­er manager.

Persico’s research is based on the premise that the val­ue of a project is only real­ized on its com­ple­tion. But he acknowl­edges there are occa­sions when this is not true. If I’m a con­trac­tor and I only get paid when a house is ful­ly remod­eled, then my best option is not to work on sev­er­al hous­es at the same time — I’m bet­ter off fin­ish­ing up the first one quick­ly and get­ting paid for it.” He con­tin­ues: But if, rather, I am a plumber and I am being paid on an hourly basis, then it makes no dif­fer­ence to me whether I task jug­gle or not.” 

Still, there may nonethe­less be costs asso­ci­at­ed with switch­ing between gigs: even an hourly plumber los­es time and mon­ey trekking from one job to anoth­er. And for many knowl­edge work­ers, the only valu­able project is a fin­ished one — if only because a client or super­vi­sor can­not eval­u­ate it until it is done.

In his research, Per­si­co has quan­ti­fied what most peo­ple already under­stand about mul­ti­task­ing: that work­flow slows as projects increase. But now we are able to grasp this intu­itive phe­nom­e­non on a math­e­mat­i­cal lev­el. If I can make a com­par­i­son that is prob­a­bly too ambi­tious,” Per­si­co says with a laugh, every­body intu­itive­ly under­stands that grav­i­ty makes things fall down. But there is still a great advan­tage in know­ing the exact math­e­mat­i­cal law that gov­erns … the force that attracts bod­ies to each other.”

Art­work by Yev­ge­nia Nayberg.

Featured Faculty

Nicola Persico

Professor of Managerial Economics & Decision Sciences, Director of the Center for Mathematical Studies in Economics & Management

About the Writer

Jessica Love is the staff science writer and editor for Kellogg Insight.

About the Research

Coviello, Decio, Andrea Ichino, and Nicola Persico. Forthcoming. “Time Allocation and Task Juggling.” The American Economic Review.

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