Chapter 18: Attention & Higher Cognition

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I want to start today by taking you into a medical mystery.

It's a story that sounds like it was ripped straight out of a neurological thriller, but it's very much real.

It centers on a woman named Parminder.

Yes.

And the text describes her family in a really touching way.

They were known for being bid -hearted.

Right.

Just generous, friendly, wonderful people.

But, and this is the strange part, in a cruel twist of linguistic fate, they were also bad -hearted in the medical sense.

That is a tragic irony.

There was a significant history of cardiovascular issues in her lineage.

And when Parminder reached her 68th year, that genetic legacy caught up with her.

She suffers stroke.

And strokes are unfortunately common, but what happened to Parminder was, well, it was statistically incredibly rare.

She didn't just have one stroke.

No.

She suffered two very specific strokes separated by a few months.

And the location of these injuries is what makes this case such a cornerstone of neuroscience.

The first stroke damaged a region in her left parietal lobe.

The second stroke, months later, damaged the exact, and I mean exact identical region in her right parietal lobe.

So she had these perfect mirror image injuries.

Both sides of the parietal lobes were essentially knocked offline.

Exactly.

Bilateral parietal damage.

And normally when we hear stroke, we think of paralysis

or facial drooping, maybe the inability to speak.

Sure.

The classic signs.

Right.

And initially, her doctors might have feared the worst.

But a few weeks after that second stroke, Parminder seemed

surprisingly okay.

Yeah, that's what's so strange.

She could speak perfectly fine.

Her memory was sharp.

She knew who she was.

She knew her family.

Her intellect was totally intact.

Even her vision, technically speaking, was fine.

She wasn't blind.

Her retinas were working.

The signals were getting to the brain.

But her perception of reality had fundamentally shattered.

She had lost the ability to see more than one object at a time.

This is the part I had to read three times to really wrap my head around it.

The source material describes it so vividly.

If she looked at her husband's face, she could see his face.

But if he was wearing glasses, she could see the glasses or are the face, but never both at the same time.

It is a condition called somal technosia.

It's a profound restriction of attention.

Imagine a world where your visual attention is a tiny pinhole spotlight.

Okay.

You can illuminate one thing a spoon, but if there's a bowl right underneath that spoon, to you, the bowl simply does not exist.

It's not that it's blurry.

It is cognitively absent.

The text actually says she was lost in space.

She was because without the ability to perceive the relationship between objects, to see the spoon in the bowl or the glasses on the face, you lose the scaffolding of space itself.

You're living in a world of isolated floating fragments.

And that mystery, the case of Parmunder, is our gateway into today's deep dive.

We are unpacking chapter 18 of behavioral neuroscience, which is titled Attention and Higher Cognition.

And it is the perfect starting point because Parmunder's case forces us to confront a question we usually just ignore.

What actually is attention?

We think of it as just focusing or paying attention in class, but when we look at Parmunder, we realize attention is so much more than that.

It is the glue that binds our visual reality together.

Without it, the world just, it falls apart.

So our mission today is huge.

We are going to go from the biological definition of attention, what is it really, down into the electrical wiring, the literal neurons that make it all happen.

We're going to talk about what happens when those networks fail, like in Parmunder's case or in some other, frankly, bizarre disorders.

And finally, we're going to end on the biggest mystery of them all.

Consciousness.

Consciousness.

It is a massive topic.

And maybe the best place to anchor ourselves is with a definition from, well, the grandfather of American psychology, William James.

He wrote this all the way back in 1890, and it still holds up beautifully.

He said,

everyone knows what attention is.

It is the taking possession by the mind in clear and vivid form of one out of what seems several simultaneously possible objects.

Everyone knows what attention is.

It feels so intuitive, doesn't it?

It's the spotlight.

It's my choice to look at the bird instead of the tree.

But scientifically, we have to be much more precise than everyone knows.

We need to draw a hard line between attention and arousal.

These are often confused.

Okay, let's break that down.

Arousal is, it's just being awake, right?

Yeah.

Your level of alertness.

Essentially, yes.

Arousal is your global level of alertness.

Are you in a deep sleep?

Are you groggy?

Are you hyper caffeinated and wide awake?

That is arousal.

Right.

But you can be highly aroused, panicked, and have completely scattered attention.

Attention is the selective process.

It's the filter.

It is the mechanism that says, okay, I am going to ignore these million sensory inputs and process this one thing for meaning.

So arousal is like the power switch on the computer, but attention is the mouse clicking on a specific file.

That is a great analogy, a perfect analogy.

And we execute that click in two primary ways.

There is the obvious way, which we call overt attention.

That's me turning my head to look at you right now while you're speaking.

Correct.

You are orienting your sensory organs, your eyes, your ears,

toward the target to get the best possible signal.

But there's also covert attention.

This is the sneaky attention.

Precisely.

And this was demonstrated by the German physicist Hermann von Helmholtz way, way back in the late 19th century.

He built this box with a screen inside that he could illuminate with a spark of electricity.

Wow, a literal spark.

A literal spark.

This was before light bulbs were common.

And he found that he could keep his eyes fixed on a central point, just staring dead ahead.

But he could mentally shift his focus to the corner of the screen.

So his eyes didn't move an inch, but his mind's eye did.

Exactly.

When the spark flashed, he could identify the letters in that corner where he was mentally focusing, even though he wasn't looking directly at them.

He proved that attention can be decoupled from your gaze.

You can look one place, pay attention to another.

I feel like everyone does this on a first date.

You're looking at your date's face, but you're covertly attending to the waiter walking by with a tray of food to see if it's yours.

That is a perfect example of covert spatial attention.

You are shifting the spotlight of your mind without moving the spotlight of your eyes.

And that spotlight concept is so crucial.

Our attention really does act like a beam, shifting around the environment, highlighting specific things for processing while leaving, well, leaving the rest in the dark.

Let's talk about that leaving things in the dark part, because that implies there are limits.

We can't possibly pay attention to everything at once.

And the most famous example of this is something we've all experienced probably too many times, the cocktail party effect.

Yes.

This is one of the most robust and frankly fascinating findings in psychology.

But let's really pause and think about the physics of it.

Imagine you are at a crowded party.

There's a jazz band playing, glasses are clinking, and 50 people are talking at once.

A nightmare for recording audio, by the way.

An absolute nightmare.

Exactly.

Now think about your ear.

It's just a funnel.

It catches sound waves.

All those sounds, the music, the laughter, your friend talking right in front of you, they are physically mixing together in the air before they even hit your eardrum.

Right.

Your ear receives one single, muddy, complex pressure wave.

It's like blending 10 different soups together in a bowl.

So how on earth do we unmix the soup?

How do I hear my friend and somehow ignore the guy laughing five feet away?

Your brain has to solve a massive engineering problem.

It uses cues to segregate the streams.

First, it uses what we call binaural cues, basically spatial origin.

Binaural meaning two ears.

Two ears.

If your friend is slightly to your right, the sound hits your right ear a fraction of a millisecond before your left ear.

Your brain uses that tiny, tiny delay to triangulate their location in 3D space and essentially tag that voice.

So I can mentally lock on to the coordinates x, y, z.

My friend is right there.

Right.

And secondly, it uses pitch and tone.

Your brain latches onto the fundamental frequency of your friend's voice and creates a filter that says, pass this frequency, reject everything else.

It effectively tunes your auditory cortex like you're tuning a radio.

But the source material mentions that there's a specific party foul that makes this much, much harder.

Alcohol.

Yes.

And this is biological.

It's not just behavioral.

Alcohol acts as a depressant on the central nervous system.

Specifically, it seems to dampen the processing power of the auditory cortex.

It essentially widens that tight filter we just talked about.

So instead of a laser beam on my friend's voice, I have a big, wide floodlight.

Exactly.

The filter gets leaky.

You start letting in all the background noise.

And as the night goes on and people have a few more drinks, everyone's filters start to fail.

So what do they do?

They talk louder to be heard.

They talk louder.

And then the person next to them has to talk louder to be heard over them.

It's a feedback loop.

It creates a feedback loop called the Lombard effect.

The room gets exponentially louder because everyone is shouting to overcome their own failing auditory filters.

That explains so much about my college years.

It wasn't just enthusiasm.

It was failing neuroscience.

Now, scientists didn't just study this at parties.

They took it into the lab with something called shadowing experiments.

This is the classic dichotic presentation setup.

You put headphones on a participant.

In the left ear, they might hear a story about, say, politics.

In the right ear, a completely different story about gardening.

Okay.

And they are told to shadow the left ear, meaning repeat word for word out loud what they hear in the left ear as it's happening.

Which is incredibly hard to do, by the way.

You have to hyper -focus.

You do.

It takes all of your attentional resources.

And afterward, the researchers ask the million -dollar question,

what did you hear in the right ear, the one you were ignoring?

And the answer is usually nothing.

Almost nothing.

It's stunning.

They can usually tell you if the voice was male or female.

They can tell you if it was a human voice or just buzzing sound.

But they cannot tell you the content.

Not a single word.

Not a single word.

They often don't even notice if the language in the unattended ear changes from English to German.

That is wild.

It's like the unattended ear just hits a brick wall.

It suggests a very, very strong filter.

However, there is a famous catch.

Let me guess.

If someone says your name.

If someone says your name in the unattended ear, you will often notice it.

It pops out.

Ah, the cocktail party exception.

You hear your name from across the room.

But wait, this creates a logical paradox, doesn't it?

It does.

Lay it out.

Okay.

If I hear my name, that means my brain must have processed the meaning of the sound.

It had to know it was my name before it could decide to pay attention to it.

But if the filter blocked it out before processing the meaning, I shouldn't have heard it in the first place.

You have just stumbled into the great early selection versus late selection debate of the 20th century.

Let's unpack that.

What's the difference?

So the early selection model, which was proposed by Donald Broadbent, says we filter things out immediately at the sensory level.

Think of a bouncer at a club entrance who checks your ID before you even get inside.

Okay.

Irrelevant stuff is tossed out before it ever reaches the meaning center of the brain.

But the name phenomenon contradicts that.

Right.

So the late selection proponents argued that the bouncer is actually at the door of the VIP section, which is consciousness.

They argued that we process everything for meaning subconsciously and then only let the most important stuff into our conscious awareness.

So who won the debate?

Is the bouncer at the front door or the VIP door?

The current consensus, largely thanks to a researcher named Nilly Levy,

is a resolution called Perceptual Load Theory.

And the answer is, it depends on how tired the bouncer is.

I love that.

Explain.

Think of attention as a fuel tank of processing resources.

If you are doing a task that is incredibly difficult, so high perceptual load like solving a complex math problem or searching for a contact lens on a patterned rug.

Oh, that's the worst.

It is.

You use up all your fuel.

You have no resources left.

In that case, the filter happens early.

You literally don't process the background because you can't afford to.

But if I'm doing something easy,

like just watching TV.

If the task is simple, low load, you have leftover fuel.

Your brain, being an information gathering machine, inadvertently processes the background chatter because it has the spare capacity.

That's when late selection happens and you get distracted by your name or conversation across the room.

So if I'm really, really focused on a hard problem, I'm essentially deaf and blind to everything else.

Effectively, yes.

And blind is the key word here.

This leads us directly to the visual equivalent, the phenomena of inattentional blindness.

The gorilla.

We have to talk about the gorilla.

The famous study by Simas and Chabris.

I'm sure many listeners have heard of it, but it's worth breaking down.

Participants watch a video of two teams, one in white shirts or one in black shirts, passing basketballs around.

And your job is to count the passes made by the white team.

Right.

So high perceptual load.

You have to track the ball, ignore the black shirts, and keep a running count.

It's not easy.

Not at all.

In the middle of the video, a person in a full gorilla suit walks into the frame, stands in the very middle of the circle, beats their chess, and then walks out.

The whole thing takes about nine seconds.

And people just miss it.

About half the people completely miss it.

They are so focused on the ball that their brain literally deletes the gorilla from their reality.

When they're told about it later, they are shocked.

They often accuse the researchers of switching the video on them.

But the textbook has an example that I found even more disturbing than the basketball game because the stakes were, well, life and death.

It involved radiologists.

This was a study from 2013 and it is chilling.

Researchers asked a group of trained radiologists to screen CT scans of lungs looking for cancer nodules.

These are experts.

This is what they do for a living.

Right.

They're highly trained.

Highly trained.

The researchers inserted a picture of a gorilla, a tiny but clearly visible gorilla, into the lung scam.

A gorilla in the lungs?

Yes.

And it wasn't even that small.

It was 48 times larger than the average cancer nodule they were looking for.

Okay.

So did they see it?

83 % of the radiologists missed it.

83%.

And here's the kicker.

Eye tracking technology showed that many of them looked directly at it.

Their eyes physically fixated on the gorilla pixels.

But they didn't see it.

They didn't see it.

Because their attentional set, their mental search filter, was tuned to white, round cancer nodules, their brains simply did not perceive the gorilla.

That is terrifying.

It shows that seeing isn't just about having your eyes open and light coming in.

It's about what your brain is prepared to find.

Precisely.

Attention creates our reality just as much as our eyes do.

Okay.

So we've established that attention is a filter.

It's a limited resource and it can make us literally blind to things that are right in front of our faces.

But let's get into the mechanics of it.

There are different types of attention, right?

It's not just one thing.

Right.

Broadly, we distinguish between voluntary attention and reflexive attention.

Okay.

So voluntary is what I'm doing right now.

I'm trying to focus on this script.

I'm trying to ignore the fact that I'm a little hungry.

Yes.

Voluntary attention is endogenous, meaning it comes from within.

It is top down.

You have a goal.

I want to find my car keys on this messy desk.

And you consciously direct your spotlight.

Okay.

It is relatively slow to activate.

It can take a few hundred milliseconds,

but it can be sustained for a long, long time.

And reflexive.

Reflexive attention is exogenous coming from the outside.

It is bottom up.

If a loud glass smashes on the floor behind you or a bright flash of light appears in your periphery, your attention snaps to it automatically.

You don't choose to do it.

Right.

It's a reflex.

It's a reflex.

It's very, very fast, but it also fades very quickly.

Scientists actually measure the speed of these things using queuing paradigms.

And I want to visualize this for you, the listener, because it explains so much about how our brain anticipates the future.

So imagine you are sitting at a computer.

You are told to keep your eyes fixed on a cross in the center of the screen.

Your task is simple.

Press a button as soon as you see a target, say a small dot, appear anywhere on the screen.

Easy enough.

It's a reaction time test.

But there's a twist.

Before the target appears, you get a cue.

In the case of voluntary attention, maybe an arrow appears in the center pointing to the right.

That arrow is a hint.

It's telling you, hey, the target is probably going to appear on the right side.

So I mentally shift my spotlight to the right side of the screen, even though my eyes are still locked on the center.

Exactly.

That's covert attention and action.

Now, if the target actually appears on the right, what we call a valid cue,

your reaction time is incredibly fast.

You are primed and ready for it.

But if the arrow points right and the target appears on the left, it's an invalid cue and your reaction time is significantly slower.

Because I have to mentally drag my spotlight all the way from the right side back over the left before I can even begin to process the dot.

Precisely.

That time cost, those extra milliseconds, is the physical time it takes for your attention to move across your mental space.

But here is where it gets really interesting with reflexive attention.

This is the inhibition of return.

Yes.

So instead of an arrow, let's use a reflexive cue, like a bright, sudden flash on the right side of the screen.

Your attention snaps there instantly, automatically.

If the target appears in that spot immediately after the flash, you are very fast.

But if there is a delay,

say the flash happens and then 200 milliseconds or more pass, and then the target appears in that same spot,

you are actually slower to respond.

Wait, that seems counterintuitive.

The flash grabbed my attention.

I should be ready.

Why would I be slower?

Because your brain is smart.

It's efficient.

It basically says, okay, a flash happened over there.

I looked.

Nothing interesting was there.

I am now going to mark that spot as boring and inhibit my attention from returning there for a little while.

That makes so much sense from an evolutionary standpoint.

If I'm a hunter -gatherer looking for berries in a forest, I don't want to keep checking the same empty bush over and over again.

Exactly.

Inhibition of return is a foraging mechanism.

It prevents our reflexive attention from getting stuck in a loop.

It forces us to scan new unexplored areas of the environment.

Speaking of scanning, let's talk about visual search.

This is the where's Waldo part of the brain.

The text distinguishes between two main types,

feature search and conjunction search.

This is a fun one you can try at home.

Imagine I show you a picture filled with dozens of green circles, and I hide one single red square in it.

I see it instantly.

It just pops out of me.

It pops out.

That is feature search.

You're looking for one unique attribute, red.

It doesn't matter if there are five green circles or 5 ,000.

The red square jumps out because your brain processes a unique feature like color in parallel across the whole visual field.

You don't even really have to search for it.

But then there's conjunction search.

This is harder.

Now, imagine you're looking for a red circle, but the background is a mix of red squares and green circles.

Oh, that's much, much harder because now the red isn't unique and the circle isn't unique either.

I can't just look for red.

I have to look for the specific combination of red and circle.

Exactly.

You're looking for the conjunction of features.

In this case, the target does not pop out.

You have to move your attentional spotlight from item to item.

Is this a red circle?

No, that's a red square.

Is this one?

No, that's a green circle.

It becomes a serial one by one process.

It takes time.

And this leads to something called feature integration theory, which sounds fancy, but it's basically about how the brain glues different features together.

It is the glue theory.

The idea proposed by Anne Treisman is that your brain has separate maps for different features.

You have a color map that knows where all the red things are and a separate shape map that knows where all the circles are.

But they're separate files, basically.

They're separate files.

To know that this specific object is both red and d a circle, you have to shine your attentional spotlight on that exact location in space.

Attention is the act of binding the maps together for that one spot.

So without attention, we just have a soup of redness and roundness and squareness floating around in our perception.

In a way, yes.

And there's evidence for this.

If you flash an image of multicolored letters too quickly for attention to work properly, people make what are called illusory conjunctions.

What's that?

They might report seeing a red X when what was actually on the screen was a red O and a blue X.

Their brain grabbed the red from one object and the X from another and accidentally glued them together because attention didn't have time to do its job correctly.

That explains so much about why eyewitness testimony can be so unreliable.

I saw a man in a red hat.

Well, maybe you saw a red car drive by and a man in a hat at the same time.

It's very possible.

Attention is the binding agent of perception.

Okay, let's go deeper.

We've talked about behavior.

Now I want to plug into the matrix.

What is happening electrically in the brain when we pay attention?

The text talks about ERPs.

Event -related potentials.

This is how we track the speed of thought in a way.

To understand this, imagine a football stadium filled with 50 ,000 people screaming.

That is your brain's baseline activity.

It's always active regulating your heart, thinking about lunch, feeling your shoes.

It is incredibly noisy.

And the signal, the brain's reaction to one specific thing, like a flash of light, is just one person whispering in that stadium.

That's a perfect way to put it.

The electrical signal of seeing a flash is tiny measured in microvolts.

It gets completely drowned out by the stadium roar.

So to find it, scientists use a clever trick.

They average the data over many trials.

How does averaging help?

They show you that flash of light 100 times and they record the brain wave 100 times.

Because the stadium noise is random people yelling at different times.

When you average it, it cancels itself out.

It goes to zero.

But the whisper, the brain's reaction to the light, happens at the exact same moment every single time.

So when you stack and average the recordings,

that consistent signal gets reinforced and rises out of the noise.

And what does that signal look like when we are paying attention versus ignoring something?

It is dramatic.

We see a specific wave called the P1 effect.

It happens incredibly early, about 70 to 100 milliseconds after the visual stimulus appears.

Wow, that's instantaneous.

It is faster than you can think.

Oh.

And here's the key.

If you are paying attention to the location where the light flashes, that P1 wave is huge.

It's a big clear spike.

If you are ignoring that location, the P1 wave is tiny, almost non -existent.

So it's proof.

It's physical proof that attention is boosting the signal right at the very beginning in the sensory cortex before you were even consciously aware of what you were seeing.

Exactly.

It's a huge piece of evidence for that early selection idea we talked about earlier.

The text also mentions a wave called the N2PC.

What's that one?

Yes.

The N stands for negative, 2 for about 200 milliseconds.

This wave appears when you are mentally focusing on a specific item during a visual search.

It's essentially the electrical signature of your attentional spotlight moving and locking onto something.

If we see the N2PC shift, we know you found the target.

That's the crowd view.

The EEG looking at millions of neurons at once.

But I want to zoom in.

If we could shrink down and put a tiny microphone next to one single brain cell,

what does attention do to it?

This was the part of the chapter that really blew my mind.

The single unit recordings.

This is one of the most elegant findings in all of neuroscience.

It involves a compound called the receptive field.

Right.

Define that for us.

Every neuron in your visual cortex has a receptive field.

It's the specific patch of space in the outside world that it looks at.

It's like the neuron's personal window on the world.

Okay.

So Neuron Bob is in charge of looking at the top left corner of my vision.

Pretty much.

Yeah.

Now imagine Neuron Bob's window is fairly wide.

It can see a generic patch of the upper left.

If you were just sitting there passively, the window is wide open.

But if you direct your attention to a specific object within that window, say a bird sitting on a branch,

something incredible happens.

What?

Neuron Bob's receptive field actually shrinks.

It shrinks.

It physically changes its property.

It remodels itself.

It sharpens.

It wraps tightly around the bird and actively excludes the distracting branches and leaves nearby.

That is incredible.

So attention isn't just some vague concept of thinking harder.

The physical hardware of the eye to brain connection changes its tuning properties on the fly.

It's like the neuron puts on blinkers to block out the distraction.

Exactly.

It actively excludes the noise.

The brain literally reshapes its sensitivity at the cellular level to give you a clearer, more high definition picture of what you care about.

We also have to mention the subcortical stuff, the more ancient, deeper parts of the brain, because it's not just the shiny new cortex doing all this work, right?

No, not at all.

We have very old structures that are absolutely crucial.

The superior colliculus in the midbrain, this helps guide your eye movements.

It's the structure that frogs use to snap their tongues out of flies.

If this is damaged, you have trouble moving your eyes toward a target.

It's essential for overt attention.

And the pulvinar.

The pulvinar is a nucleus deep in the thalamus.

The thalamus is like the brain's central relay station.

The pulvinar acts like a switchboard operator for attention, helping to shift and orient your focus.

If you inhibit the pulvinar in monkeys, they really struggle to shift their attention to new things.

They get stuck.

So we have this ancient hardware moving the eyes and shifting the focus, and then the more modern cortex is doing the high level filtering and selection.

Let's map out those cortical networks.

The text mentions two main streams, or systems.

Yes, a good way to think of them is the goal setter and the circuit breaker.

I like that.

Let's start with the goal setter.

This is the dorsal frontoparietal system.

That's a mouthful, so just think top down.

This network includes the intraparietal sulcus, the IPS,

and the frontal eye field, or FEF.

This is the system that is active when you consciously decide, I am going to look for a yellow taxi.

It holds the map of your goals and directs your eyes and attention accordingly.

And the circuit breaker.

That's the right temporoparietal system.

Correct.

This system involves the temporoparietal junction, or TPJ, which is located a bit lower down in the brain.

This system is specialized for reflexive, bottom -up attention.

It's usually quiet when you are focused on a task.

But if something unexpected and relevant happens, a flash, a loud noise, a tiger jumping out of the bushes, this system fires up and interrupts the dorsal system.

It basically shouts, hey, stop looking for the taxi.

Look at the tiger.

Exactly.

It breaks your current focus to alert you to potential danger or novelty.

And crucially, this reflexive system is strongly lateralized to the right hemisphere of the brain.

Which is a perfect transition to what happens when these systems break.

And this is where the chapter gets really heavy with some fascinating clinical disorders.

We started with Parmander, but let's talk about the most common disorder of attention,

hemispatial neglect.

Hemispatial neglect is fascinating and honestly quite heartbreaking to witness.

It usually happens after a stroke damages the right parietal lobe.

And because that right hemisphere controlled attention for both sides of space, but predominantly the left,

damage here causes the patient to completely ignore the left side of the world.

And when you say ignore, listeners might think, oh, so they're blind in their left eye or their left visual field.

No, and that is the hardest part for people to grasp.

Their eyes work perfectly.

The retina captures the photons from the left side of space.

The signal goes to the brain.

But the concept of left has been deleted from their mental operating system.

The examples in the text are just wild.

Patients will be served a plate of food.

They will eat everything on the right side of the plate and then stop complaining that they're still hungry.

And if you, as the clinician, rotate the plate 180 degrees, so the uneaten food is now on their right.

They see it.

They will gasp and say, oh,

where did all this food come from?

And then they'll eat the rest.

Or they will shave only the right side of their face.

Or put makeup on only the right side.

The clock drawing test is the classic diagnostic tool here.

You ask the patient to draw a clock face from memory.

A simple task.

You draw a circle.

You put the numbers one through 12.

They will draw the circle.

No problem.

But then they will squash all the numbers.

One, two, three, all the way to 12 into the right hand side of that circle.

The entire left side is left completely blank.

But wouldn't they look at that drawing and say, wait, that looks all crowded on one side.

Why is half the circle empty?

They don't.

To them, it looks perfect.

Because the left side simply doesn't exist to be filled.

The concept of leftness is gone.

There's also this really specific phenomenon called extinction.

Extinction is a more subtle form of neglect that really reveals the competitive nature of attention.

If you stand in front of the patient and wiggle a finger on their left side, they'll see it.

OK.

If you wiggle a finger on their right side, they'll see it.

They aren't blind.

But if you wiggle fingers on both sides at the exact same time, what happens?

They only report seeing the right one.

The good signal from the right visual field

completely overwhelms and extinguishes the weaker signal from the damaged left side.

It shows that our attention is a constant battleground for resources.

And with a damaged parietal lobe, the left side always loses that battle.

And the most disturbing part of this for me is the anosognosia.

The denial of illness.

It's profound.

These patients will often argue with you.

You point out that they haven't finished their food or that their left arm is paralyzed and they might make up an excuse or say it belongs to someone else or just genuinely not understand what you mean.

They do not know that they are neglecting half the universe.

It really, really challenges your sense of reality.

It implies that my entire reality, everything I think is out there, is just a construction project going on inside my head.

And if the foreman of that project calls in sick, half the world just vanishes.

That is the profound philosophical insight of this whole field of study.

We don't see reality.

We see our brain's model of reality.

And neglect reveals the glitch in the matrix.

Which brings us full circle back to Parminder.

She didn't have neglect.

She had balance syndrome.

Right.

Because Parminder had bilateral damage, both sides of the parietal lobe were injured.

Balance syndrome is a classic triad of three specific debilitating symptoms.

First, simultagnosia.

That's the one thing at a time symptom we discussed at the very beginning.

Okay, that's one.

What's the second?

Second is oculomotorapraxia.

This is a difficulty in voluntarily steering your gaze.

Parminder might want to look at your face.

She knows where your face is.

But her eyes just won't move there on command.

It's like the steering wheel of the eyes is disconnected from the driver.

And the third.

Optic ataxia.

This is an inability to reach for objects using visual guidance.

So if I hold out a pen to her, Parminder can see it.

Assuming it's the only thing she's attending to.

But if she tries to grab it, she will miss.

She will grope blindly in the air, often just inches from the object.

It really highlights that seeing something and acting on what you see are totally different brain pathways that can be separately damaged.

Precisely.

Balance syndrome disconnects the what system from the where and the how systems.

It's a devastating fragmentation of visual motor control.

So if attention is the gatekeeper, what lies behind the gate?

We have to pivot now to the biggest, most difficult topic in all of science.

Consciousness.

C -word.

It is.

It is slippery.

It's not just arousal.

It's not just attention.

It involves awareness of your own existence, the passage of time,

and a sense of volitional control.

The text mentions the default mode network, or DMN.

This seems to be a big key to understanding the resting mind.

It is.

For a long time, scientists focused on what parts of the brain light up when you do a task.

But then, around the turn of the century, they noticed something interesting.

When you stop doing a task, when you just sit there and stare at a blank wall,

the brain doesn't shut down.

A very specific, widespread network actually lights up.

That's the default mode network.

So this is the daydreaming network, the mind -wandering network.

Yes.

It involves parts of the frontal, temporal, and parietal lobes.

It seems to be the seat of introspection, self -reflection,

and metacognition, which is just a fancy word for thinking about thinking.

It's the part of you that replays an awkward argument you had five years ago while you were in the shower.

And interestingly, the text says that in disorders like autism or schizophrenia,

the connectivity within this network is often altered.

Yes.

But where we really see the powerful link between attention and consciousness is in states of reduced consciousness, like comas or vegetative states.

There is a story in the text that gave me chills.

It's about locked -in syndrome and how researchers used an fMRI machine to basically talk to people who couldn't move a single muscle.

This is the work of Adrian Owen and his colleagues.

It is absolutely incredible.

You have patients who are diagnosed as being in a vegetative state.

They are completely unresponsive.

But the researchers put them in an fMRI scanner and gave them instructions through headphones.

They said, imagine you are playing tennis.

Why tennis?

Specifically.

Because imagining playing tennis, swinging a racket, running around the court

activates the supplementary motor cortex in a very specific, recognizable way.

What happened?

And in some of these patients, people who have been unresponsive for years, the motor cortex lit up.

It looked just like the brain of a healthy, conscious person imagining tennis.

Then they said, now imagine walking through all the rooms of your house.

And the parahippocampal gyrus, a spatial navigation area, lit up.

So they were conscious.

They were in there the whole time.

They were listening.

They were attending.

They just couldn't move their bodies to signal it.

The researchers were even able to use this to ask yes or no questions.

Imagine playing tennis for now.

Imagine walking through your house for no.

That is profound.

It completely redefined how we diagnose consciousness.

But it also highlights the difference between the hard problem and the easy problem of consciousness.

Yes, a distinction coined by the philosopher David Chalmers.

The easy problem, which is not actually easy at all, is identifying the objective brain patterns.

When you look at a rabbit, neurons A, B, and C fire in this pattern,

we can theoretically solve that.

We are solving that.

And the hard problem.

The hard problem is qualia.

Why does neuron A firing feel like the color red?

Why does a specific frequency of air pressure vibration feel like the sound of a cello?

Why does it feel like something to be you?

Why aren't we just biological robots processing data without any internal movie playing?

And the answer to the hard problem is?

We have no idea.

The textbook is very honest about this.

We're not even close to bridging that expandatory gap between matter and subjective experience.

Well, while we wait on the hard problem, let's talk about something we do know a bit more about.

Executive function,

the CEO of the brain.

The prefrontal cortex, or PFC, this is the most evolved part of the human brain.

It takes up a huge percentage of our cortex compared to cats or even chimpanzees.

It is responsible for planning, impulse control, working memory, and decision making.

And you really can't talk about the PFC without talking about Phineas Gage.

We need to tell his story properly because it is the founding myth of this entire field.

Phineas Gage, the man, the myth, the medical miracle.

The year is 1848.

Gage is a railroad construction foreman in Vermont.

And he wasn't just some random guy.

The records say he was sharp, capable.

He was the best foreman they had.

Efficient, capable, smart, polite.

A good businessman.

He was the guy you wanted in charge of the crew.

And then the accident.

He was packing explosive powder into a hole in a rock.

He was using a tamping iron.

A huge metal rod, over a meter long, about an inch thick, pointed at the tip.

He turned his head for a second to look at his men.

The iron struck a spark against the rock, and the powder ignited.

The iron rod shot upward like a missile.

It entered under his left cheekbone, went behind his left eye, plowed straight through the front part of his brain, his frontal lobes, and exited out the top of his skull.

It landed about 80 feet away, covered in blood and brain matter.

And the craziest part of the story, he didn't die.

He didn't even lose consciousness for more than a moment.

He sat up.

He rode in an ox cart back to town.

When the doctor arrived, Gage was sitting on the porch and famously said, Doctor, here is business enough for you.

That is just pure adrenaline talking.

But he physically healed.

Right.

He did.

He lost the eye.

But he was walking and talking within a few months.

But, and this is the absolute key to the story, he wasn't Gage anymore.

His friends and family said Gage was no longer Gage.

How did he change?

What was different?

He went from being a responsible, well -liked leader to being fitful, irreverent, and incredibly profane.

He couldn't stick to a plan.

He would devise some scheme for the future, and then abandon it five minutes later for something else.

He had no social filter.

This is the disinhibited syndrome the text talks about.

Exactly.

The rod destroyed his orbitofrontal cortex,

the part of the brain right above the eyes.

This area is the brake pedal of your personality.

Without it, Gage became a slave to his immediate impulses.

If he wanted to say something rude, he said it.

If he wanted to quit his job, he quit.

He lost the ability to simulate the future social consequences of his actions.

It's so fascinating because it separates intelligence from character.

He was still smart.

He could do math.

His memory was fine.

But he couldn't be a responsible person anymore.

It suggests that morality and social propriety aren't just abstract things we learn in school.

They are biological functions housed, at least in part, in the orbitofrontal cortex.

The text actually outlines three distinct types of prefrontal syndromes.

Gage had the disinhibited type.

What are the other two?

The second is disexecutive syndrome.

This comes from damage to the dorsal lateral PFC, the side part.

These patients have major trouble with planning and task switching.

They have what's called cognitive impersistence.

They just can't stay on task.

So they can't manage their goals.

Right.

If you ask them to sort a deck of cards by color, they can do it.

But if you then say, OK, now I want you to sort the same cards by shape,

they can't switch.

They get stuck on the old rule.

And the third syndrome.

Apathetic syndrome.

This is from damage to the medial frontal area, the middle part.

These patients lose their spark.

They lose spontaneity.

They might sit in a room and not speak or move for hours unless you ask them a direct question.

It is a profound loss of the will to act.

It's amazing how personality can be fractionated like that.

You can lose your filter or you can lose your drive or you can lose your ability to plan, depending on which centimeter of the frontal lobe is damaged.

It connects to this new field called neuroeconomics, the science of how our brains make choices.

We like to think we are rational beings, but the brain has these different, often competing systems.

The text calls them the valuation system and the choice system.

Right.

The valuation system involves the ventromedial PFC, the same area damage engaged, and the dopamine reward system.

It's the emotional calculator.

It asks, is this yummy?

Is this fun?

Is this worth the risk?

The choice system involves the dorsolateral PFC.

It's the more logical processor that actually weighs the options and executes the decision.

And there was a study with rats that proved you can actually hack the system.

Yes, they took rats that were natural gamblers, risk -preferring rats that like to go for big, uncertain rewards.

They used optogenetics, using light to control specific neurons to stimulate their dopamine receptors.

By overstimulating the anxiety and valuation signals, they instantly turn them into cautious,

risk -averse rats.

Wow.

They changed their economic personality with the flip of a light switch.

So my entire investment strategy might just depend on how my dopamine receptors are firing on a particular morning.

That's probably a bigger factor than you would like to admit.

We are coming to the end of the chapter now, and we have to talk about the cutting edge section.

Mind reading.

Is it real?

Or is it still just science fiction?

It is.

It is becoming real.

This ties back to that easy problem of consciousness we mentioned, identifying objective brain patterns.

Researchers put subjects in an fMRI scanner and had them watch YouTube clips.

Just random videos from the internet.

Pretty much.

Planes flying, Steve Martin doing comedy, nature scenes.

While they watched, the computer monitored the activity in their visual cortex.

It built a huge model, essentially learning when the brain makes this pattern of activity, the eyes are seeing a vertical line.

When the brain does that, the eyes are seeing movement to the right.

So the computer was learning the unique visual language of that person's brain.

Exactly.

Then came the test.

They showed the subjects new movie clips, ones the computer had never, ever seen.

And they asked the computer to reconstruct what the movie looked like, just by reading the brain waves.

And could it do it?

The results are spooky.

You can see them in the textbook.

It's blurry, for sure.

It looked like a surreal dream.

But if the person was watching a clip of Steve Martin in a white suit,

the computer reconstructed a blurry but recognizable image of a man shape in white.

If they watched a plane fly across the screen, you saw a plane -shaped blob moving across the reconstruction.

So we can read the visual cortex.

We can, in a blurry way, see what someone else is seeing.

We can.

But the limit, and this is a very important limit, is that we can't read thoughts yet.

We can read the sensory input, the movie playing on the screen at the visual cortex.

But we cannot read the memory of your grandmother or your abstract concept of justice.

That data is stored in a much more complex, distributed way.

We aren't in the movie inception yet.

Yet.

So we've traveled all the way from the single neuron sharpening its receptive field to block out distractions, to the parietal lobes that allow us to see a face and glasses at the same time, to the executive planner in the front of our brain, and finally to the edge of reading the mind itself.

It is a long journey.

And it really brings us back to that core idea from the beginning.

Attention is the gatekeeper of reality.

We are bombarded by an infinite amount of information every single second.

Without these mechanisms, the filters, the spotlights, the suppressors, we wouldn't be conscious beings.

We would just be confused, overwhelmed inputs.

As William James said all that time ago, my experience is what I agree to attend to.

It's a very empowering thought.

But in the modern world, it's also a bit of a warning.

How so?

Because if your experience is defined by what you attend to, then what happens when you lose control of your attention?

What happens when algorithms on your phone or devices on your wrist are specifically designed to hijack that spotlight for profit?

In a very real neurobiological sense, if you aren't controlling your attention, you aren't controlling your life.

You are letting someone else write the script of your reality.

That is a provocative thought to leave you with.

If technology can one day literally read our visual attention, and if modern distractions are constantly fracturing it,

are we losing a fundamental piece of ourselves?

It's something to mull over before you check your next notification.

Indeed.

Thanks for listening to this deep dive into attention and higher cognition.

This has been the Last Minute Lecture Team.