illusion with excercises!

Presented ByM. Shaharyar Saeed

ILLUSIONs

An illusion is a distortion of the senses, revealing how the brain normally organizes and interprets sensory stimulation

Sensations can be defined as the passive process of

bringing information from the outside world into the body and to the brain. The process is passive in the sense that we do not have to be consciously engaging in a "sensing" process.

What your mind feels or registers.

Perception can be defined as the active process of selecting, organizing, and interpreting the information brought to the brain by the senses.

What your mind fells or registers and also interprets.

1- Optical illusions or Visual Illusion

2- Physiological illusions

3- Distorted Illusions

4- Motion illusion

Optical illusions are intriguing example of how easily the mind can get confused.

You probably recognize the face in this painting but if you look at his hair, you'll see that he is fighting a fire-breathing dragon.

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Are the squares above marked A & B the same color or different?

Proof: They are the same. The shadow causes an illusion of white.

Adelson`s „Checker-shadow illusion“

Adelson EH (1993)Perceptual organization andthe judgment of brightness.Science 262:2042-2044

Luminance & Contrast

Which line is longer? They are actually the same size.

Eye-movement theory: Arrowheads influence extent of eye movements

Pictures converted in our brain from 2-dimensional drawings to represent 3-dimensional scenes

Different level of explanation – does not propose a mechanism for perception

Well established, although some ‘loopholes’ have been found

Cochran’s photo of his ‘freemish’ crate (1966).

Any guesses?

Viewing the image from a misleading perspective

Viewing from another angle wrecks the effect.

Of course not!

But how?

Adelbert Ames, Jr. (1946) – concept by Helmoltz

Special viewpoint – monocular Floor, ceiling, some walls, & windows

are trapezoidal Inclined floor Appears as a normal

cubic room

A split between perception & expectation

Apparent cubic perspective overrides sense of size constancy

Stanford psychologistRobert Shepherd – use background & relationship to the horizon to judge size

The Pool

David MacDonald

Count the black dots. Do they keep moving?

Are the purple lines parallel or curved?

What do you see on the left? What do you see on the right?

Can you believe that all the gray lines above are perfectly parallel?

Stare at the blue circles and move your head back and forth from the screen. Do the outer circles move?

Can you believe that this is a picture and not an animation? To check, just

focus on one leaf for 5 seconds.

How many legs does the elephant have above?

Do you see a spiral or circles?

Do you see one woman or two women looking at the candle?

Which way are the cubes facing? Up or down?

Are the balls inside or on the shelf?

What do you see? A sax player or a human face?

Can you believe that all the red lines make perfectly straight lines?

Who is down and who is up?

Kanisza figure (Gaetano Kanisza)

Effect: subjective or illusory contours

Congnitive- / Gestalt Field

Effect: subjective or illusory contours

What word do you see?

Thank You!

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