Optical Illusions

[Chipmonker]

I recently did a project on visual phenomenon for a physics class of mine. Anyway I found these really neat illusions on the web that are interesting enough to share x_x

 

Warning: If you begin to feel sick at any time, cover your left eye with your hand, close the window and lie down.

 

http://img412.imageshack.us/my.php?image=blindspotsy0.png - Blind Spot Illusion

How it works: Lean towards your computer and close your left eye. Look with your right eye at the 'a'. Then move your focus up the alphabet until at a certain letter or spacing the black dot disapears (i.e. you can't see it in you peripheral vision). It happens around the letter 'e' for me.

Why it works: Where the optic nerve (cordlike thingy) attaches to you eye, there are no cones/rods (light recievers) so the brain doesn't see the spot.

 

http://www.johnsadowski.com/big_spanish_castle.php# - Color Aftereffect

How it works: Stare at the cross in the middle of the picture and then mouse over it (the mouseover is all black and white - Really, I'm not lying :laughingsmiley: ).

Why it works: The brain adapts to the signals sent to it. For example staring at red paper and then looking at something white, one will see a cyan image (WHITE (RBG) - RED = Blue + Green Light = Cyan)

 

http://www.michaelbach.de/ot/mot_adapt/index.html - Motion Aftereffect

How it works: Stare at the cross until the picture changes. The computer screen will "move"

Why it works: Same as color aftereffect; the brain adapts to signals and "ignores them." You get the same result when you spin around in circle really really fast.

 

http://www.ritsumei.ac.jp/~akitaoka/saishin2e.html - Moving Static Pictures (Scroll Down)

How it works: Look at one point in the picture. The rest of the picture will move.

Why it works: (Theory) The eye twitches all the time to refresh the picture and "moves" the picture

 

http://img260.imageshack.us/img260/862/ambiguousio2.png - Ambiguous Figures

How it works: Starting at the top left and going clock wise,

Picture 1 - A seal and trainer or a dancing man and woman

Picture 2 - A duck or rabbit

Picture 3 - A dog sniffing the ground

Picture 4 - An old lady or a young woman

Picture 5 - A man on a horse or a face

Why it works: The pictures can usually look as one of two things. Which one we see first or better is based on your perception, which in turn is affected by your heritage, gender, age, intellegence, etc.

 

http://www.michaelbach.de/ot/mot_freezeRot/index.html - Random Cool Illusion

[.Dan.]

Physics? Was it involving light and the human eye's blindspots?

[Ellie_Penguin]

well as soon as i closed my left eye (on the first one) the black dot dissapeared, then when i moved my vision it dissapeared at the letter "i". Very interesting!

[Anime]

I got it around C. Weird. I've always thought these things were cool.

[Foxy!]

Wow, those really rocked! I especially liked the castle one.

[Superfly]

*poke* I got to letter F, then it goes away, the wierd thing is, when I look at the rest of the letters I can see the dot perfectly fine, its just letter F when I can't. huh?

[Radiance]

For me, it disappeared around the letter d. soo freakyy but coooool :)

[Mira]

We saw most of these in science class once. Austin was positive that there was something wrong with his eyes. XD

[Chipmonker]

My blind spot is around the letter "F" - It's different for everyone. And, if you are older, the blind spot will be larger due to the wear and tear on the eye.

 

And another random fact - The Müller-Lyer effect (meaning this line >----< looks longer than <---->) isn't cross-cultural. Those who are descendants of the non-Western cultures (mainly Africa and Asia) aren't as affected by it. To *most* of them the line looks the exact same length, no matter which arrows are used.

 

Physics? Was it involving light and the human eye's blindspots?

I'm in a random beginners advanced class. We have like 2 weeks of nothing to do (finals are next Thursday) - so the teacher made us do projects on "Why we see what we see and why we hear what we hear." I tied in some physics concepts like how the the eye's biconvex lense works.