1. Perception and Reality Things Are Not Always As They Seem...
Is Seeing Always Believing?

2. Is Seeing Always Believing? Overview
Still Visual Illusion Slideshow
Forced-choice Worksheet
Answer the questions on the handout as we move through the slideshow
There are no right or wrong answers right now; just answer what the pictures look like to YOU
Discussion of Answers
As we go through the illusions a second time:
How could we double-check (verify) whether what you (or anyone else) are seeing is what is actually there?

3. Do you see any black dots (circles)?
Hermann Grid
Do you see any black dots (circles)?

4. Are the Two Vertical Lines Straight or Curved?
Hering Illusion
Are the Two Vertical Lines Straight or Curved?

5. Café Wall Illusion
Are the Gray Lines Below All Parallel? Are the blocks all the
same size? Are the blocks moving?
(b) Are the Gray Lines Below All Parallel (or slanted)? Are the Blocks Rectangles?

6. Checker-Shadow
Which Square is Darker, A or B?

7. Neon Color Spreading
Do you see a Red ball when there are no Black lines?
Do you see a Red ball when the Black lines appear?

8. Retinex Color
How many colors do you see? List the colors.

9. One More Look…
As we go through the illusions again, for each example discuss the following as a class:
What did you see?
What did everyone else see?
How can we double-check (verify) whether what you (and everyone else) are seeing is what is actually there?

10. Do you see any black dots (circles)?
Hermann Grid
How Can
We Test It?
Do you see any black dots (circles)?

11. Are the Two Vertical Lines Straight or Curved?
Hering Illusion
Are the Two Vertical Lines Straight or Curved?
How Can
We Test It?

12. Café Wall Illusion How Can We Test It?
Are the Gray Lines Below All Parallel? Are the blocks all the
same size? Are the blocks moving?
(b) Are the Gray Lines Below All Parallel? Are the Blocks Rectangles?
How Can
We Test It?

13. Checker-Shadow Which Square is Darker, A or B? How Can We Test It?
Do you agree this
bar is the same
Luminance
(shade of gray)
from top to bottom?

14. Neon Color Spreading
Do you see a Red ball when there are no Black lines?
Do you see a Red ball when the Black lines appear?
We Can Already
See That the
Black Lines Cause
Us to See Something
That Is Not There

15. Retinex Color How many colors do you see? List the colors. How Can
We Test It?

16. Retinex Theory of Color
The Cheeseburger is Really Just a Combination of:

17. Don’t Believe It? Take a Closer Look…
Retinex Color
Don’t Believe It? Take a Closer Look…

18. Conclusions
Perception is: Our personal view of the way the world is; how it seems to each of us.
Reality is the way the world actually is.
Sometimes what we think is going on (perception) is incorrect (different than reality). How do we know?
(a) other people can have different perceptions and show us how ours is incorrect,
(b) our other senses can give different information,
(c) we can compare it to perceptions of other things in the world we are more certain of (like a ruler).
* By understanding why we sometimes make mistakes, we might be able to avoid mistakes in the future…