A woman sits at a table reading a book while using chopsticks to eat noodles.

Why Can’t I Multitask?

OK, can you can multitask, as long as the tasks don’t conflict with each other. You can hold your breath while you text a message (no conflict). However, you can’t sing a song while you’re drinking a glass of water (conflict).

The brain can experience conflicts, too. While it’s easy to recite a telephone number while you’re dialing it, it’s difficult to complete the Stroop task of reading the names of colored letters when the letters spell out a different color.

How does the cerebral cortex organize mental tasks to prevent conflicts? That is the job of attention, perhaps the most important executive function of the brain. While attention is often occupied making sense of our ambiguous sensations using a process called binding, it also delegates cognitive resources where they’re needed most. Unfortunately, those resources are limited. Focusing on shopping or meeting someone at the mall can make us forget we left the baby in the car.

Attention is not one process. It comprises three prominent processes, according to Michael Posner: alerting, orienting, and executive attention. Executive function performs two crucial operations in perception: spotlighting information that needs deeper analysis, and filtering out irrelevant distractions. Although the filter may be more important than the spotlight, the spotlight has an interesting pulsatile character.

Executive attention is such a high-level function that we are often unaware of its limits. Once we are paying attention to something, there’s simply no higher part of the mind to watch where our attention is going. Fortunately, a loud honk will catch the attention of drivers who keep texting at an intersection after the red light changes.

Multitasking illustrates this, too. When we are juggling tasks it feels like we manage them simultaneously, but that’s often not the case.

More often, we try to cope with competing demands for our attention by switching attention. Trying to juggle different objects of attention can be helpful but it doesn’t always work and interruptions can be stressful. Attention is limited in capacity and speed, keyed to the limitations of the brain, we discover.

You can have fun with these limitations, but they’re a nuisance when we have several things to do at once. One way to look at the limitations of executive attention is to see its operations as serial, one-at-a-time, rather than parallel. The lower, brainstem-level processes that carry out executive commands are more often parallel, going on simultaneously.

So multitasking is a bit of a myth, for a variety of reasons. If we excelled at multitasking,  rubbernecking wouldn’t cause traffic backups.

True multitasking is impossible. Psychologists call our attempts task-switching.  That is, we can perform multiple tasks that call on different resources, but we can’t dribble two balls with the same hand very well, physically or mentally. Trying too hard just produces overload or choking. (As Dan Simon of “Gorilla” fame puts it, we can’t talk, whistle and chew gum at the same time.) Doesn’t mean we don’t like it. ☺

The exceptions are supertaskers. It may not be something we can learn, but there are diagnostic tests like this one. For the rest of us, everyday life can be a real challenge. The overload* degrades attention. But then we have forgetting as a helper. We’ll get to more on that later, but for now do overload and the forgetting that results from it explain infantile amnesia–why we can’t remember infantile memories?

A prevailing metaphor to illustrate the problem is the bottleneck. Eventually we all run out of resources and encounter the infamous bottleneck.

Bottlenecks are familiar to us in a variety of ways: traffic, ketchup, even sheep at a gate. Attention shows several bottlenecks, such as the psychological refractory period and the attentional blink.

Somewhere, someone is probably calling for a program to eliminate the bottlenecks and speed up our thinking. I’m not so sure that the bottleneck is a bug. I think it’s a feature.

Consider that there are many more sensory neurons than motor neurons. We are aware of more than we can act upon. The bottleneck is not just a limitation on what we perceive but on what decisions we can make.

So even if we could fully and quickly analyze everything we see and hear, what good would it do? We can’t multitask. Instead we want to know what’s going on–what’s the gist?–in order to decide what action to take.

As I see it, provisionally and for the time being, the bottleneck is analogous to a manager’s span of control. The executive systems of the brain may not want too many inputs, just the most important ones.

*An exabyte is one quintillion bytes.

A multi-armed man holds tools for many different tasks.

BIO: The major attentional systems of the brain were discussed in another topic. Although the orienting reflex and some basic discrimination tasks reveal attentional processes in a wide variety of mammals such as rats and humans, the systems of selective attention that we are discussing in this topic may be restricted to humans—in fact, to human adults. As with other executive functions, it develops largely through learning.

PSYCHO: Stress impairs attention switching, though, curiously, it does not impair response reversals*. (Response reversal in escaping a burning building would appear as changing from pushing on the door to pulling, while attention switching would be looking for an axe instead of pushing the door.)

There’s a cost to switching attention. It’s one source of mental fatigue. (Another is making tough decisions.) The cost may increase with age as a cause of irritability, for example.

One hundred years ago the Zeigarnik effect was first reported. It is improved memory for uncompleted tasks over completed tasks. (Watch out for uninformed websites that describe interruption as a way to increase the accuracy of your memory for a job. That is not what Zeigarnik reported!)

A few bloggers (here’s one) have written that the cost of switching attention comes from an accumulation of attention residue. I would suggest taking this with a grain of salt–in fact, the whole salt cellar. This is based on a claim by Sophie Leroy (and adopted by others) that first used that label for the performance decrement caused by switching tasks and then used it to explain the same performance decrement! That’s circular reasoning. Her report came out a little after the paper by Liston, McEwen, and Casey that I linked to as “impairs attention switching”, above.

In all likelihood there is no “attention residue”. If there were such a residue in the brain, its physical form would probably be soluble in coffee and hot chocolate! As attention fatigue**, it will blow away if you take a walk or climb a mountain.

Attention varies with our environment and how we fit into it. Paying attention with our feet can help in the office and halfway up the nearest coconut tree. Compared to some talented feet, most of us qualify as rather deficient, psychopodiatrically speaking. Of course, if we were efficient multitaskers it would be a blow to stage magicians.

Magicians learned to exploit our attention long before there were psychologists to study them. Part of the trick is that we think we see things that we really don’t. We wouldn’t enjoy magicians performing the retention vanish as much as we do if we were accurate recording machines. The NY Times article featured a not-to-be missed video of the trick (which you can try for yourself).

Nowadays it may seem that for every magician as good as Apollo Robbins there are ten psychologists looking over his shoulder. And there are a few charlatans out there, too, trying to take advantage of a childlike trait, magical thinking***, which tempts many adults.

The misperception that magicians create in us exploits two attentional quirks called change blindness and inattentional blindness, which you can see also here (change) and there (inattentional).  And of course misdirection can be found in many other places.

Which effect do you think was demonstrated in this illusion? But that’s just a trick. Magic should also open our eyes to the hidden worlds around us every day, hiding in plain sight (video here).

Distractibility is a personality trait with some stability as part of a person’s temperament.

That means that some folks will almost never lose themselves in a piece of music or while climbing a mountain road on a bicycle. This may not be an impediment to success as a writer or a cook or even a musician.

Goleman perhaps could have mentioned that self-regulation and working memory capacity count, too.

As with so many traits described on the Internet, you can diagnose yourself here and there with unvalidated tests.

Probably most of us will score about in the middle, since a lot of traits vary broadly even if they are not normally distributed in the population. Though I’m happy with cosmic silence**** when I work, it’s clear that a lot of folks prefer some music in the background. (Maybe that’s not a perfect example, because the effect of background music depends on the task…like, um, surgery.)


*There’s one study that found different results.

**That’s the Stroop task mentioned in the introduction to this discussion topic. You can find more here and there.

***from Oxford Handbook of the Development of the Imagination, 2013.

****There aren’t a lot of music psychologists. Williamson is one of them. A leading “distractologist”, Adam Gazzaley, agrees with her explanation of music’s effects.

SOCIAL: The warnings against multitasking seem to fall apart in social situations. Don’t we often carry on conversations in a group, talking to several people at once?

This involves the process of social attention. Part of a conversation is tracking the gazes of other participants, and the neural networks of gaze-following are under investigation.

But unless we’re all talking about the same thing, which constitutes really one conversation, multitasking gets us in trouble when we really have to concentrate on the subject at hand. We can’t keep track of the difficult conversation (or do much of anything else) while we’re monitoring a cell-phone exchange, for example. Think of the stress of being interrupted while you’re firing someone at work or breaking up with a long-time partner.

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