This is the PPT on Illusion with some excercises.

1. Presented By
M. Shaharyar
Saeed

2. ILLUSIONs

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

4.  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.

5.  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.

6. 1- Optical illusions or Visual Illusion
2- Physiological illusions
3- Distorted Illusions
4- Motion illusion

7.  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.
7

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

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

10. Adelson`s „Checker-shadow illusion“
Adelson EH (1993)
Perceptual organization and
the judgment of brightness.Science 262:2042-2044
Luminance & Contrast

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

14.  Eye-movement theory: Arrowheads influence
extent of eye movements

15.  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

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

17. Any guesses?

18.  Viewing the image from a misleading
perspective
 Viewing from another angle wrecks the
effect.

20.  Of course not!
 But how?

21.  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

22.  A split between perception & expectation
 Apparent cubic perspective overrides sense of
size constancy
 Stanford psychologist
Robert Shepherd – use
background &
relationship to the horizon
to judge size

23. The Pool
David MacDonald

24. Count the black dots.
Do they keep moving?

25. Are the purple lines parallel or curved?

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

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

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

29. Can you believe that this is a picture
and not an animation? To check, just
focus on one leaf for 5 seconds.

32. How many legs does the elephant
have above?

33. Do you see a spiral or circles?

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

35. Which way are the cubes facing?
Up or down?

36. Are the balls inside or on the shelf?

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

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

39. Who is down and who is up?

42. Kanisza figure (Gaetano Kanisza)
Effect: subjective or illusory contours
Congnitive- / Gestalt Field

43. Effect: subjective or illusory contours

44. What word do you see?

55. Thank You!
!!!