You've taken in way more information than you

could possibly remember in detail-- things

you've seen, heard, smelled, touched, and tasted.

But somehow, some information gets

stored in a way that lets you access it later.

So what makes this process work?

Our brains are really complicated,

so scientists have come up with models

to represent how our brain takes in and makes sense

of information in our environment.

One of the most influential models

is the information-processing model,

which proposes that our brains are similar to computers--

we get input from the environment, process it,

and output decisions.

It's important to note that this model doesn't really

describe where things happen in the brain.

It's more conceptual.

The first stage, then, is getting the input,

which occurs in sensory memory.

This is sometimes also called the sensory register,

so if you hear that term, just know

it's the same thing as sensory memory.

And this is where you first interact

with the information in your environment.

It's a temporary register of all the information

your senses are taking in.

Even though you have five senses,

the two most studied in terms of memory are sight and sound.

So within sensory memory, you have

iconic memory, which is memory for what you see,

and echoic memory, which is memory for what you hear.

One of the really interesting things about sensory memory

is that it lasts a different amount of time

depending on the modality of the information coming in.

So visual information is incredibly vivid,

but it only lasts for less than half a second.

Auditory information.

on the other hand, lasts a little bit longer.

It lasts for about three or four seconds.

So if you've ever tuned out of a conversation

and your friend gets mad that you're not listening to them,

you can thank echoic memory for helping

you remember the last thing they actually said.

So we have a ton of information coming into our sensory memory,

but we can't possibly process all of it.

We decide what to pay attention to,

and that gets passed along into working memory to be processed.

Working memory is just whatever you're

thinking about right at this moment.

And it's also called short-term memory,

but we're going to stick with working memory

because that's what psychologists call it.

Working memory capacity works a little bit differently.

It's not defined by time so much as quantity.

Just remember the magic number seven.

Your working memory can hold about seven plus or minus

two pieces of information at a time, so about five to nine.

This does vary a little bit based

on how complicated those pieces of information

are, how old you are, that kind of thing.

But generally, it's right around seven.

And an interesting fact is that this is actually

why phone numbers started out as seven digits long.

It was determined that that's as many pieces of information

as a person could hold in mind without getting numbers

confused or mixing them up.

And just like sensory memory has different components

for different types of input, working memory

has different components to process

those distinct types of input.

Visual and spatial information, like pictures and maps,

are processed in the aptly-named visuo-spatial sketchpad,

while verbal information, meaning words and numbers,

are processed in the phonological loop.

Again, think of repeating a phone number

to yourself just long enough to type it in.

That's using your phonological loop.

Be careful here, though.

"Verbal information" means any words and numbers, so

words and numbers you heard that came from the echoic memory,

and words and numbers you saw that came from iconic memory.

So we've got a little bit of mix-and-match here.

Now, you might be thinking that sometimes you

need to process input place that has

verbal and visual information together,

such as a map with street names and landmarks.

In that case, you need someone to coordinate

the efforts of the visuo-spatial sketchpad

and the phonological loop.

So something called the central executive fills that role.

You can think of him kind of like a traffic cop who

directs the other components of working memory.

Once the central executive tells the visuo-spatial sketchpad

and the phonological loop to coordinate,

then they create an integrated representation

that gets stored in the episodic buffer, which

acts as a connector to long-term memory.

Long-term memory is the final stage

in the information processing model.

When stuff gets in here, it's like hitting the Save button

on your computer.

Unfortunately, our memories aren't quite as foolproof

as that.

It doesn't work perfectly.

But we can store a lot of information

in long-term memory.

Once again, there are different components

that specialize in different types of memories.

We have two main categories-- explicit, also called

declarative, and implicit, also called non-declarative.

As you can see, psychologists like

to give these things multiple names,

but fortunately, they can generally

be broken down into something that

makes sense, so don't get intimidated.

Explicit memories, for example, are facts or events

that you can clearly or explicitly describe.

So any time you take a vocabulary test or remember

the state capitals, you're using a specific type

of explicit memory called semantic memory.

And "semantic" just means "having to do with words,"

so you can think about it as being

able to remember simple facts like the meaning of words.

A second type of explicit memory is

called episodic memory, which is memory for events,

like your last birthday party.

Just like a TV episode is a sequence of events,

your episodic memory stores event-related memories.

While explicit memories are easy to define,

implicit memories are a little bit fuzzier.

They involve things you may not be able to articulate,

such as how to ride a bicycle.

You probably can't say clearly how much

pressure to put on the pedals or exactly how

to turn the handlebars.

But provided that you ever learned in the first place,

if you get on a bike and just do it,

you probably won't fall over.

Memories for procedures like riding a bike

are conveniently called "procedural memories."

The last type of implicit memory is

called priming, which means that previous experience influences

your current interpretation of an event.

For example, if I say the word "hair," what do you think of?

If you paid attention at the beginning of this video,

then you might have thought of "hair" as "H-A-R-E,"

meaning "rabbit," because you were primed with the bunny

picture at the beginning.

Your recent experience of seeing a bunny stayed in your memory

and influenced your interpretation of the word

that I said.

If you weren't paying attention, or if you've maybe had to push

your hair out of your face in the last few minutes,

then you might have thought of "hair" as "H-A-I-R,"

because it's generally a more common word.

With all these components of memory,

you might be wondering how much it can actually hold.

I think we've all had the feeling that we can't possibly

take in any more information, and while it might be true

but you can't process any more information at the moment,

unlike like the computer in front of you, as far as we

know, long-term memory capacity is unlimited.

So your brain never actually gets

too full for more information.