The Exploratorium
Science Snacks
Snacks about Perception

Snack name

Description

Afterimage

A flash of light prints a lingering image in your eye.

Anti-Gravity Mirror

It's all done with mirrors!

Benham's Disk

A rotating black-and-white disk produces the illusion of color.

Bird in the Cage

Stare at a color and see it change.

Blind Spot

To see or not to see.

Bronx Cheer Bulb

Some lightbulbs appear to wiggle and flash when you give them the raspberry, but the only thing wiggling is you.

Cardboard Tube Syllabus

Your brain combines information from your eyes in surprising ways.

Cheshire Cat

Make a friend disappear, leaving only a smile behind.

Colored Shadows

Shadows are not all black and white.

Depth Spinner

What happens when you get off the merry-go-round?

Disappearing Act

If you want to stay hidden, you'd better stay still.

Everyone is You and Me

See yourself become someone else.

Fading Dot

Now you see it; now you don't. An object without a sharp edge can fade from your view.

Far 0ut Corners

Your experience of the world influences what you see.

Gray Step

Without a boundary, it's hard to distinguish different shades of gray.

Jacques Cousteau in Seashells

There's more to seeing than meets the eye. 

Magic Wand

See pictures in thin air.

Moire Patterns

When you overlap materials with repetitive lines, you create moire patterns.

Peripheral Vision

We are not usually aware of our eyes' limitations.

Persistence of Vision

Your eye and brain hold on to a series of images to form a single complete picture.

Pinhole Magnifier

Who needs expensive optical equipment?

Proprioception

Even with our eyes closed, we have a sense of body position - where our arms and legs are, for example, and that we are moving them. Muscles, tendons, joints and the inner ear contain proprioceptors, also known as stretch receptors, which relay positional information to our brains.

Pupil

Your pupil changes size to control how much light enters your eye.

Real Image

Create the image of an object in space using a $2 ornament.

Seeing Your Blind Spot

See your blind spot.

Seeing Your Retina

 

You can use a dim point of light to cast a shadow of the blood supply of your retina onto the retina itself. This will allow you to see the blood supply of your retina, and even your blind spot.

Sense of Taste

Receptors on our tongues bind to chemicals in our food and relay the information about the chemicals to our brain. Surprisingly, all those wonderful tastes are transmitted to our brains through only four types of receptors on our tongues - those for sweet, sour, salt and bitter.

Size and Distance

A clueless way to determine the size of an object.

Spinning Cyclinder

A spinning rod with a mark near one end is set rotating and spinning at the same time. Amidst the blur of the spinning cylinder, the mark appears three times, forming a stationary triangle.

Squirming Palm

This visual illusion makes the palm of your hand appear to squirm and twist.

Thread the Needle

Using two eyes gives you depth perception.

Vanna

A face seen upside down may hold some surprises.

Whirling Watcher

When you view short bursts of moving images, you see some interesting effects.