WEBVTT

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Voiceover: Let's look at
the difference between

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top-down and bottom-up processing.

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So, what is bottom-up processing?

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Bottom-up processing basically
begins with the stimulus,

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so let's imagine that
we're looking at something,

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or let's say I'm looking at a banana.

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The banana is sitting there and

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it influences what we perceive.

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So, stimulus influences what
we perceive, our perception.

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So, if I know absolutely
nothing about something,

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then the stimulus or whatever
it is I'm looking at,

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yet I don't know anything
about, I've never seen it,

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I don't have any preconceived
cognitive constructs

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about what it is I'm looking at.

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The stimulus basically is
influencing my perception.

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So, for example let's imagine that

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I'm looking at a cockpit of a plane.

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I'm not a pilot, so I'm not really

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too familiar with everything and

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everything kinda looks fairly confusing.

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So, basically all the different stimuli,

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so this stimulus, a bunch of gauges,

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and this rudder-looking thing,

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I'm basically looking at all the different

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little parts of something
that is new and novel to me,

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and trying to kind of comprehend
what it is I'm looking at.

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So, this is bottom-up.

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This is when you start
with no preconceived idea

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of what it is that you're looking at,

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and allow the stimulus to influence

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your perception of what it
is that you're looking at.

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So, bottom-up processing is data-driven,

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and your perception of what
it is that you're looking at

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directs your cognitive
awareness of the object.

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So, in contrast, top-down processing

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basically uses your background knowledge,

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so uses your background knowledge

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to influence perception.

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So, let's look at this example over here.

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So, what we're actually
seeing are a bunch of circles,

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they are just a bunch of circles and then

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inside the circle there are
a couple of lines drawn.

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So, we are looking at this set of circles,

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these white circles with
lines drawn inside of them.

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We are creating this cube.

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We're basically taking
these lines and then

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putting them together in
order to create a cube.

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Even though the stimulus itself,

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which is the circles with the lines,

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actually doesn't draw a cube because

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there are these black spaces over here,

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and there is absolutely
nothing in the black spaces,

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but our brains are basically
taking this information

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and using our knowledge of cubes

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and what they're supposed to look like,

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we're recreating a cube despite a lack of

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a cube actually being
present in the image.

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So, that's top-down processing.

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It's using your background information,

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your background knowledge, your learning,

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your expectations, in order to influence

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what it is that we're perceiving.

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So, in other words, it's theory-driven.

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We look at this and we assume that

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they're trying to represent a cube,

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even though one's not
actually drawn there,

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and we're using that theory in order to

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shape our cognitive understanding

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of what it is that we're looking at.

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So, our perception, our behavior

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is influenced by our expectations,

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which is top-down processing.

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So, we're using what's
already in our heads

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in order to perceive what
it is that we're looking at,

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whereas in bottom-up
processing we're using

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the stimulus itself in order
to drive our perception.

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So, another good example of top-down

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processing would be "Where's Waldo?"

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So, in "Where's Waldo?", we have a

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mental idea of what we're trying to do,

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which is to find Waldo amidst this

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really jumbled mess of a picture.

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So, if we were using bottom-up processing

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in order to look at this we would just

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be seeing a whole bunch of little people,

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and we wouldn't really be goal-driven,

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we wouldn't be trying to do anything,

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but with top-down
processing we have a goal,

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and we're able to look
through here to find Waldo.