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This is the PPT on Illusion with some excercises.
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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!
!!!