All right. I'm going to start out
with a challenge for you. I'm going to show you
a series of shapes, and I want you to count
the number of yellow stars that you see. Also, count the number of red
X's that pop up on the screen, so that's two
separate numbers, one for how many yellow
stars you see and one for how many red
X's come up on the screen. All right. So that was probably
a challenging task because you had to count
two different things and I kept talking to you while
you were trying to do that. That's an example of
divided attention, which we'll talk about
in just a second. But first, you probably
want to see how you did. So let me show you
everything you just saw. All right, this is everything
that popped up on your screen. There were 15 yellow stars and
13 red X's, and also one smiley face. Don't worry it if you
didn't see this guy. We'll talk about that later. But now that you have
a good example of how limited a resource
your attention is, let's talk more about it. When you're paying
attention to something, that means that you're
concentrating on it at the exclusion of the other
stimuli in the environment. A lot of times, though, we
try to divide our attention and do multiple things at once. So maybe you watch
TV while studying, or try to count yellow stars
while trying to count red X's. The thing is, as you
just saw, attention is a limited resource, and we
can't split it all that well when it comes to
complicated stimuli. So if you're trying to
do two things at once, you usually end up switching
between those tasks rather than doing
them simultaneously, even if you're switching so
fast you can barely tell. So think back to when you
had to count the yellow stars and the red X's. You couldn't really do
that at the same time. You had to kind of
flip back and forth. When you switch,
or if you do just intend to focus on
one thing at a time, you're exercising your
selective attention. You can think of selective
attention like a flashlight beam on some aspect
of your environment. You can move the
flashlight around, depending on what
you want to focus on, but at any given moment,
it's illuminating one particular area of
interest, and everything else is just kind of dimmer. So the question is, what
causes your flashlight beam to swing around and focus
on one thing or another? There are two types of cues
that can direct our attention, exogenous and endogenous. Exogenous cues are external
to any goals we might have, meaning we don't have
to tell ourselves to look for them in order for
them to capture our attention. They include things like
bright colors or loud noises, because you can be in the middle
of a gripping conversation and have every intention
on focusing on it, but a loud noise will still
cause your focus to shift. And with salient visual cues,
the ones that really stand out, this is called the
pop-out effect. Something just pops out at
us, like a yellow circle amidst a bunch of green circles. Endogenous cues,
on the other hand, are more internalized
and higher order, meaning they involve
the internal knowledge to understand the cue
in the first place, and the intention to follow it. Take an arrow, for example. If you didn't know
what an arrow meant, then you wouldn't
know to follow it. It's just some random
lines on a piece of paper. But because you have
the internal knowledge of what an arrow is,
you can carry out an intention to look
where it's pointing. One really good example
of selective attention is the cocktail party
effect, which you've probably experienced yourself
multiple times. And this is your ability to
attend to one voice even amidst many others. And it most commonly occurs
when you hear your own name amid those voices. So, for example,
picture the last time you had a big family
dinner, and you're at one end of the table
talking with someone, and then Grandma down at
the other end of the table says your name. And even though you
haven't been listening to grandma's conversation,
you instantly swing your flashlight
beam of attention down to hear what
she's saying about you. And if you had to
guess what type of cue your name was in that
situation, endogenous or exogenous, what
would you say? If you said endogenous,
then that's right. Because it was the
meaning of your name that drew your attention
to when Grandma said it. All right. So now we know that different
cues draw our attention to certain stimuli, whether
we want them to or not. But what happens
to all the stuff we're not paying attention to? Scarily enough, we
experience something called an inattentional
blindness, which means that we're not consciously
aware of things that happen in our visual field when our
attention is directed elsewhere within that field. So think back to
that smiley face from our demo in the beginning. Because you were focused on
yellow stars and red X's, you might have missed the
smiley face, especially because he kind of blended
in with the yellow stars. And that's a minor example,
but inattentional blindness happens in more
important situations too. For example, can you
say exactly where the nearest fire
extinguisher is? If you're like most people, you
probably go by this every day when you're going to your home
or office or wherever you are, but very few people
actually pay attention to where things like
fire extinguishers are, even though they're
bright red and they can be necessary
for our survival. Usually your attention
is directed elsewhere, so you fail to notice
the fire extinguisher. Closely related to
inattentional blindness is change blindness,
which is when we fail to notice changes
in the environment. Now be careful,
because the difference between change blindness
and inattentional blindness is subtle but important. Inattentional blindness
means that you miss something right in front of you,
while change blindness means that you fail to
notice a difference between a previous state
and a current state, like when you don't notice
when your mom gets a haircut or you get back to
your room and don't notice that furniture or books
are in a different place. And this is actually
very common as well, so don't feel bad if
it happens to you. In fact, there's one
really good example when a researcher stopped
people on a busy street and asked for directions. And part way through when
the people were giving their directions, a large
bookcase was carried between them and the
researcher, and he swapped places with a different person. And almost no one noticed. And very few people even
noticed when the new person was a different race or gender. So it was just a great example
of our limited attention and our ability to
focus on one thing to the exclusion
of everything else.