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Attention is the focusing of our mind's lens on the world. Our brain is constantly taking in our surroundings and forming predictions about what we may see next. Like a camera focusing on the world, our mind focuses on thoughts, facts, conversations, sounds, or smells, shaping the course of our conscious experience.

It seems that attention exists obviously in the humans and higher primates. But it extends down the evolutionary scale quite far. I've come across papers that claim to be studying selective attention in Drosophila, for example— in fruit flies. So it's very widespread.

You might wonder, why? What do we need attention for?

There's actually a lot of different approaches to thinking about what attention does for an organism from an evolutionary perspective. There's way too much information out in the world to conceivably process in an efficient way.

An organism needs some way of deciding what's important information and focusing on that. And so we don't sit around worrying about the direction that the sunlight is coming from, if that's not going to help us figure out where a predator is going to come from.

And so attention is those presettings, or the way that we are preset to focus in on what seems to be just the kind of information that we need to get around and survive in the world. And not spend a lot of time processing information that's not really important or useful.

Life is pretty easy when we're just focusing on one thing, but a lot of the time we find ourselves moving through our day with divided attention. While the brain is a massively parallel machine with millions of neurons processing information at the same time, it seems that as a whole, the brain is more suited for single attentive moments rather than split attention.

And we like to think that we're able to attend to two tasks at the same time. It turns out that we're probably actually not that good at it. And any time we're attending to two or more tasks at the same time, there's some costs.

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There's some very wonderful examples to think about in the real world. Maybe the one that's most current is the notion that it's dangerous to use a cell phone while you drive. And it is.

There have been studies that show that a cell phone conversation— I'm not even talking about texting, just the normal cell phone conversation— is essentially the equivalent of having a blood alcohol level of 0.08, which is of course the legal criterion for being under the influence of alcohol. So it's illegal to drive at a 0.08 level, and yet that's what a cell phone conversation does.

So not only that, but the driving also impairs your cell phone talking. So it's a two-way street, and it's a divided attention task. And you lose at both of those tasks.

Certain kinds of experiments show just how vulnerable our attention is to distraction.

A very striking example— try to imagine— well, you can't really imagine this. You have to see it on screen— or not see it. The situation is that there are a group of about six people, and they are playing a game.

You are given a task, and it might be, count the number of times the ball is passed by the people in white shirts.

Watch these players closely. See if you can count how many times the white-shirt team passes the ball back and forth to one another.

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How many passes did you count? There should be 24.

Let's go back and check the tape. Let's pause it right there. Did you notice the gorilla?

In the meantime, walking right through this group of people is a man in a gorilla suit. Many, many, many people— most people— fail to see the man in the gorilla suit.

There's nothing tricky about this. It's not like he's little. He's a normal-sized person. He's not sidling around, trying to be inconspicuous. He's walking right through the group of ball players, and you don't see him.

That is divided attention at its best. You are so taken with the task of counting the passes of the ball that you missed entirely the man in the gorilla suit.

[telephone ringing]

Hello? Oh, hi, Mom.

Attention can be shared and transmitted through very simple signals. In joint attention, an individual communicates attention through outward cues— a glance of the eyes, a nod.

Joint attention is one of the most basic forms of communication we share with other species.

We had a pretty healthy dinner, so yeah.

It's an ancient nonverbal system of directing focus around the world and communicating the presence of important stimuli to others.

Joint attention is an interesting phenomenon that's usually studied not so much by cognitive scientists or neuroscientists, as so much as by developmentalists.

It's something that develops in the first year or two of life. Infants will first develop a dyadic relationship, a one-on-one relationship with the mother. And so they will look at the mother.

Then they will enter into a state where they're willing to and interested in looking at things that the mother is looking at. So the mother might look at something, and then the child may look at the same thing. Or the mother might point, and the child will look at the same object.

It turns out to be quite important. There are some psychologists who think that joint attention is a precursor to language learning.

In some disorders, attention can go wrong. In the brain, the regions that seem to be most active as we shift attention from one object to the other are the prefrontal cortex and thalamus.

The prefrontal cortex has been tied to working memory, the ability to keep information in short-term storage for a brief period of time. If normal function of the prefrontal cortex is disturbed or hindered, it could be difficult to focus our attention on one task at a time.

The thalamus is another key region involved in attention. As the incoming sensory relay center of the brain, the thalamus can also act as a filter, separating out the important parts of our sensory experience from the useless background chaos, allowing us to focus on one sound or one face amidst the crowd.

These structures help conduct and direct our attention as we move through the world.

These days everyone seems interested in the question of, is the modern world so different from the worlds that we have experienced throughout most of human history? Such that we are really taxing our attentional and working memory and visual capacities in a way that we didn't tax them before.

One thing we might look at is research on enhancing attention. What could that be like? Well, there is work on drugs to enhance cognition.

On the other side though— and equally important— is crafting the world to fit the human.

It's not that we are in danger because there is too much stuff out there. We are in danger because we think we can process all of it at the same time. And we probably don't realize that we are actually not.

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So in all likelihood it would be a good idea to put down some of the devices, say, while we are driving. Or to put down some of the devices while we are studying for an exam or trying to learn something important.

Because while we have the impression that we're getting everything into working memory that we want— or that we are attending to everything that we want— we probably aren't. And really we couldn't possibly be, because those systems are extremely capacity limited.

Attention is one of our most valuable and fragile assets.

[music playing]

[door sliding open]

Oh. Hey, Mom.

[door sliding shut]