# Spinning Disk Illusion

A new, holiday-themed twist on the classic thaumatrope illusion.

You might have heard the term, “Faster than the human eye.” But is there really something that can happen so fast that a normal human eye can’t register it? Believe it or not, it’s absolutely possible and the Spinning Disc Illusion is a great way to learn how easily your eyes can be beaten.

## Experiment Materials

• Printer
• Card stock paper
• Glue stick
• Scissors
• Hole punch
• String or yarn

## Experiment

### 1

Start by downloading one of the  printable templates below.  Use card stock or another type of thick paper for the best results. Print one of the templates.

### 2

Use the scissors to cut out the circular templates.

### 3

Paste the pictures back-to-back with one image upside down and the other right-side up. Make sure that you align the images as perfectly as possible. We’ve placed dots on the two circles to help you match them up.

### 4

Punch holes in the far right and far left sides of the image.

### 5

Tie a 12″ length of string or yarn through one hole. Repeat with another 12″ length of string in the other hole.

### 6

Wind up the strings by holding one string in each hand and twirling the disc, moving just one hand.

### 7

Pull the strings taut and the disc will start to spin rapidly.

### 8

What do you notice about the two images? They blur into one combined image!

## How Does It Work

The secret behind the Spinning Disc Illusion is the same magic that animators use to make your favorite cartoons. When images flash in rapid succession, like when you pull the strings taut, your brain cannot process them as individual images any longer. Instead, your brain takes the two images and combines them into one “hybrid” image. When animators use this principle, they use sequential images, for example of a person running, and flash them in rapid succession to create the impression that the person is actually running. In reality, it’s hundreds, or even thousands, of individual images being blurred into one moving image. The images are moving faster than the human eye… well, actually, faster than the human brain can process the images!

## Take It Further

Now that you know how the illusion works and how the human brain processes the images, use this information, and try to make a flip book, just like the movie makers. Are you able to “trick” your eyes? Do the images look like they are blending together, just like the spinning disk illusion?

## Science Fair Connection

Preforming the Spinning Disk Illusion is pretty cool, but it isn’t a science fair project. You can create a science fair project by identifying a variable, or something that changes, in this experiment. Let’s take a look at a variable option that might work:

• Try testing the Spinning Disk Illusion on a variety of different people. Ask your participants to describe what they saw during the illusion. Were the results the same or were they different based on the age of your participants? What conclusions can you draw based on your interviews?

That’s just one idea, but you aren’t limited to that! Try coming up with different ideas of variables and give them a try. Remember, you can only change one thing at a time. If you are testing the illusion on different ages of people, make sure that the other factors are remaining the same!

• American Flag
• Blank Template
• Christmas Tree
• Easter Egg
• Menorah
• Pumpkin
• Reindeer
• Turkey
• All Templates

Try doing this experiment again by drawing your own two images. The possibilities are endless – try it out!