Perception and RealityPerception and RealityThings Are Not Always Things Are Not Always

As They Seem...As They Seem...

Is Seeing Always Believing?Is Seeing Always Believing?

Is Seeing Always Believing?Is Seeing Always Believing?OverviewOverview

Still Visual Illusion Slideshow Still Visual Illusion Slideshow Forced-choice WorksheetForced-choice Worksheet Answer the questions on the handout as we move Answer the questions on the handout as we move

through the slideshow through the slideshow There are no right or wrong answers right now; There are no right or wrong answers right now;

just answer what the pictures look like to YOUjust answer what the pictures look like to YOUDiscussion of AnswersDiscussion of Answers

As we go through the illusions a second time:As we go through the illusions a second time: How could we double-check (verify) whether what How could we double-check (verify) whether what

you (or anyone else) are seeing is what is actually you (or anyone else) are seeing is what is actually there?there?

Hermann GridHermann GridDo you see any black dots (circles)?

Hering IllusionHering IllusionAre the Two Vertical Lines Straight or Curved?

Café Wall IllusionCafé Wall Illusion(a)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?

Checker-ShadowChecker-Shadow

Which Square is Darker, A or B?

Neon Color SpreadingNeon 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?

Retinex ColorRetinex ColorHow many colors do you see? List the colors.

One More Look…One More Look…

As we go through the illusions again, for each As we go through the illusions again, for each example discuss the following as a class:example discuss the following as a class:

What did you see?What did you see? What did everyone else see?What did everyone else see? How can we double-check (verify) whether How can we double-check (verify) whether

what you (and everyone else) are seeing is what you (and everyone else) are seeing is what is actually there?what is actually there?

Hermann GridHermann GridDo you see any black dots (circles)?

How Can We Test It?

Hering IllusionHering IllusionAre the Two Vertical Lines Straight or Curved?

How Can We Test It?

Café Wall IllusionCafé Wall Illusion(a)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?

Checker-ShadowChecker-Shadow

Which Square is Darker, A or B?

Do you agree thisbar is the same Luminance(shade of gray)from top to bottom?

How Can We Test It?

Neon Color SpreadingNeon 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 AlreadySee That the

Black Lines CauseUs to See Something

That Is Not There

Retinex ColorRetinex ColorHow many colors do you see? List the colors.

How Can We Test It?

Retinex Theory of ColorRetinex Theory of ColorThe Cheeseburger is Really Just a Combination of:

Retinex ColorRetinex ColorDon’t Believe It? Take a Closer Look…

ConclusionsConclusionsPerceptionPerception is: Our personal view of the way the world is: Our personal view of the way the world

is; how it seems to each of us.is; how it seems to each of us.RealityReality is the way the world actually is. is the way the world actually is.Sometimes what we think is going on (perception) is Sometimes what we think is going on (perception) is

incorrect (different than reality). How do we know? incorrect (different than reality). How do we know? (a) other people can have different perceptions and (a) other people can have different perceptions and show us how ours is incorrect,show us how ours is incorrect,(b) our other senses can give different information,(b) our other senses can give different information,(c) we can compare it to perceptions of other things in (c) we can compare it to perceptions of other things in the world we are more certain of (like a ruler). the world we are more certain of (like a ruler).

* By understanding why we sometimes make mistakes, * By understanding why we sometimes make mistakes, we might be able to avoid mistakes in the future…we might be able to avoid mistakes in the future…