Science 4: Optical illusions
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Spoiler alert: Magicians aren't really magically materializing rabbits in hats. It's just an optical illusion. We know, we were pretty let down too.
| 4th Grade | Science |
| Elementary and Middle School | 4th Grade |
| Language | English Language |
Transcript
But for those days when we just can't get to a magic show, we have something that'll [Guy pulls a rabbit out of a hat]
take the edge off: optical illusions. [Static on a TV stops and an optical illusion appears]
To understand what an optical illusion is, it helps to break the term down into smaller [Coop pointing at a blackboard]
parts.
The first word, "optical," refers to our eyes.
The second word, "illusion," means a kind of trick.
So an optical illusion is a trick involving our eyes. [Dino pointing at a blackboard]
But who's being tricked, exactly?
If magic tricks are performed by magicians for audience members… [Magician dancing on stage]
…are optical illusions performed by eyes, for…other eyes? [Magician disappears in a puff of smoke and only his eyes are left behind]
We hope not, because we wouldn't want to clean up the seats in a big theatre after a bunch [Angry looking eyes leaving]
of eyeballs have been sitting in 'em. [Guy cleaning looks grossed out]
It turns out the sap being tricked in an optical illusion is actually the human brain. [Girls head opens]
When our eyes look at something…
…they gather and transmit a whole bunch of information to the brain, with the hope [Girl looking at a globe]
that the brain will understand what's there. [A globe sign appears in her head]
So if you look at an apple, your eyes transmit enough visual info to your brain so that it's [Guy looking at an apple on the TV]
able to think, "Hey look! [Apples going into the guys eyes]
An apple!" [An apple sign appears in the guys head]
But with an optical illusion, things aren't quite so simple.
Our eyes still gather up a bunch of information and transmit that information to the brain. [Optical illusions going into the guys eyes]
But due to weird uses of color, lights or patterns… [Guy looks shocked]
…our brain gets confused, and ends up thinking that it sees something different from what's [Two signs appear, faces and vase]
actually being seen.
And since brains tend to like getting things right, this can really hurt the brain's self-esteem. [Guy looks angry and storms out]
We can see how this works with a pretty simple optical illusion.
Take a look at these two shapes.
At first glance, it might look like the middle line in A is longer than the one in B. Okay…so
where's the illusion?
It turns out that these two middle lines have the exact same length. [Length of line A is copied onto line B to show they are the same length]
What's especially weird, though, is that even once we know the trick, the two lines still
look like they're different lengths. [The copied length is taken away]
The arrangement of the lines create a pattern that our brains just can't help but see incorrectly. [Help me sign on the guys brain]
It's the sort of trick that might not get you a two-year contract performing magic shows [An explosion goes off and the guy falls over]
on the Vegas Strip…
…but hey, at least your brain will always enjoy it. [Guy looks at an optical illusion on the stage and his mind blows up]