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Seeing is not Believing: Optical Illusions

by: Lauren Bannan, Michelle Domingo, Jeannette Ellis,
Andrea Scahill, Erin Quinn

rabbit

Is this a rabbit or a duck?
(http://www.psycsmart.com/rabbit.png)

What exactly is an optical illusion?

An optical illusion causes us to see something that may not actually exist and is often misleading to the eye. Basically, the illusion does not match up with what we think is our “reality.” This is because illusions are intended to mock what we think is reality and are therefore fooled by the illusion. Sometimes, illusions allow people to see an image in different ways. The image we see is based upon what our brain interprets when we look at the picture.

Here is an example of an optical illusion:

What do you see?

triangle

(http://www.csit.fsu.edu/~dennisl/CMS/figs/triangle400.gif)

Why Do We See Optical Illusions?

The eye and the brain work together in order for us to visualize different images in optical illusions. Optical Illusions are unique in the fact that everyone may interpret the same image differently. This is all due to perspective, or the way a person looks at something. Scientists believe that the way a person interprets an optical illusion is linked to a person’s past experiences. This is because a person’s past reflects how the brain interprets what the eye will see.

Here's what we're going to do:

Part 1: A "Global" Optical Illusion

Next, we are going to demonstrate an optical illusion, which distorts your sense of position, using a light up globe.

We previously drilled holes into the globe, in order for the light to shine though.

Once we turn off the lights, a light show should project onto the walls surrounding us.

Once we spin the globe around, watch the walls around you.

Are you moving? Is the wall moving?

Neither! The globe is actually spinning...

Part 2: The Autokinetic Effect: Is that a UFO??

First, the autokinetic effect is a perceptual illusion in which you think something is moving, when it is actually staying in one spot.

This is usually why people think they see UFOs in the sky, when it is most likely a star.

This effect is cause by small, involuntary eye movements (saccades)

Look at the light we show you in the distance for a while

Do you see any movement?

This is the autokinetic effect!!