Optical Illusions

Seeing is believing, or so the saying goes. However, as optical illusions beautifully demonstrate, our eyes, or rather our sense of sight, can be deceived into seeing something that is not real. Very few of the illusions below are caused by defects of the eye, the majority highlight misinterpretations in our brain's understanding of what it sees.

The collection below come from various web sites and represent the most impressive optical illusions I have seen. I will then go on to a tour of optical illusions from a neurological point of view, showing how some of the better known and possibly less impressive illusions actually shed light on some of the inner workings of our brain (currently under construction.)

1) How many black dots can you see?

2) Either scroll the page or slowly move the mouse cursor over the image whilst focusing on the cursor.

3) Stare at the lips on the top picture for about 30 seconds and then quickly look at the others lips on the bottom picture. You should see Marilyn blush!

4) The ring of boats appears to rotate slowly clockwise.

5) The "Dark Green" end is actually the same shade of green as the "Light Green" end. Don't believe me?

6) Stare at the red dot in the centre of the left block for about a couple of minutes. Then look over to the centre of the right block. And if that's not freaky enough, move your head closer and further from the monitor while focusing in the centre.

7) The squares marked A and B are the same shade of gray. Don't believe me?

More illusions by Edward H Adelson

8) A groovy blind spot finder: Close your left and eye and focus your right eye on the cross on the left. At some point the big circle will disappear as it crosses your blind spot. If you can't see this effect, try sitting closer/further from the screen.

9) Focus on the dot in the centre and move your head towards then away from the screen. The rings should rotate in different directions.

10) Again run your mouse over the image and focus on the cursor.

11) Come very close to the screen then scroll down till you see a square with lots of dots...

Now move away from the picture and you should see the face of a famous person!

12) Illusion of rotation.

13) Stare at the middle of the picture and see the yellow dots disappear.

14) No camera trickery is used here:
http://www.grand-illusions.com/videos/dragon%20illusion.wmv

The Grand Illusions website is full of wonderful illusions and toys such as this.

15) My personal favourite.

16) What is this a picture of?

17) Another movement illusion.

18) Stare at the lowest of the four dots in the middle for about 30 seconds then look at a white or light coloured wall. What do you see?

19) Shrinking illusion.

Spotted any impressive illusions recently? Send them to me!