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Optical Illusions

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Optical Illusions. Seeing Is Deceiving. Christopher Landauer. Science of Art. March 9, 2000 ... Optical illusions mock our trust in our senses ... – PowerPoint PPT presentation

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Title: Optical Illusions


1
Optical Illusions
Seeing Is Deceiving
Christopher Landauer Science of Art March 9, 200
0
2
What is an Illusion?
  • illusion (î-l¹zhen) noun
  • 1. a. An erroneous perception of reality.
  • b. An erroneous concept or belief.
  • 2. The condition of being deceived by a false
    perception or belief.
  • 3. Something, such as a fantastic plan or desire,
    that causes an erroneous belief or perception.
  • 4. Illusionism in art.
  • Latin root of illusion is illudere which means
    to mock
  • Optical illusions mock our trust in our senses
  • Suggest that the eye is not a passive camera
    rather,
  • perception is an active process that takes
    place in the
  • brain and is not directly predictable from
    simple
  • knowledge of physical relationships

3
Whats the big deal?
  • Human reliance on correspondence between
    conscious experience and physical reality
  • Continual verification of our senses
  • Cultural Heritage
  • Seeing is Believing
  • See it with my own two eyes

4
History of Illusions
  • Prehistory
  • Afterimage caused by glancing at the sun
  • A stick half in and half out of water

5
History of Illusions
500 B.C. - Height of the Greek Period
The eyes and ears are bad witnesses when they a
re at the service of minds that do not understand
their language -Parmenides Two Viewpoints
on Perception 1. Sensory inputs are inaccurat
e. Mind corrects these inaccuracies to
provide an accurate representation of the
environment. Illusions Senses are relied on mo
re than the Mind 2. Senses are inherently accur
ate and produce a true picture of the
environment. Mind is limited.
Illusions Mind interferes with the Senses
6
History of Illusions
c. 450 B.C. The mind sees and the mind hears.
The rest is blind and deaf. -Epicharmus
Man is nothing but a bundle of sensations
-Protagoras c. 300 B.C. We must perceive
objects through the senses but with the mind
-Plato 384 - 322 B.C. Each sense has one
kind of object which it discerns, and never errs
in reporting that what is before it is color or
sound Although, it may err as to what it is t
hat is colored or where it is, or what it is
that is sounding, or where it is. -Aristotle
7
History of Illusions
  • A. Ideal Parthenon
  • B. Architrave Illusion
  • (Jastrow-Lipps)
  • C. Illusionary Distortion
  • D. Alterations made to offset illusion

8
History of Illusions
For the sight follows gracious contours and
unless we flatter its pleasure by proportionate
alterations of the modules--so that by adjustment
there is added the amount to which suffers
illusion--an uncouth and ungracious aspect will
be presented to the spectators.
-Vitruvius
9
History of Illusions
Entasis Convexing of column to overcome paral
lel lines appearing concave Irradiation Illusio
n
Bright objects appear larger
10
History of Illusions
Conclusion More of an Art than a Science
Early Preparadaigmatic Science -Trial and
error -Aesthetic, not scientific -No factual
understanding -No treatsies -No schools of
thought
11
History of Illusions
1596 - 1650 Descartes There is both a registrat
ion stage and an interpretation stage in the
perceptual process. Perceptual error or illusion
may intrude at either of these two steps along
the road to consciousness. 1700 - 1800 Given a
t Birth vs. Learned through Experience
Reid Kant All knowledge of the ex
ternal world comes directly through the
senses and is interpreted by innate
mechanisms Berkeley Hume All per
ceptual qualities are learned through
experience with the environment
12
History of Illusions
  • 1800 - 1870 Experimental Foundations
  • Mueller, E.H. Weber, Helmholtz, Baldwin, Hering
    use Physics, Physiology, Philosophy to form
    treatises
  • Specialist and Non-specialist working in area of
    visual geometric illusions carrys on to the
    present
  • 1922 - Luckiesh lighting engineer 1964 -
    Tolansky physicist 1972 - Robinson
    psychologist
  • 1900s Revolution and Rebirth
  • Behaviorists vs. Gestalt
  • Methodology vs. Theoretical
  • Percepual response Brain wave patterns

13
Current State of Illisions
Conclusion Paradigmatic Science (Psychology)
1900s Normal Sciences Anomoly Crisis
Revolution Current status Normal Science
- mopping up - puzzle solving - guidelin
es for research
14
Ambiguous Figures
Face or Vase?
15
Ambiguous Figures
RetroActive Nels Isralson
L'Amour de Pierrot c.1905
Gossip and Satan Geo. A. Wotherspoon
16
Ambiguous Figures
Bust of Voltaire - Houdon, 1781
Slave Market With the Disappearing Bust of
Voltaire
- Salvadore Dali, 1940
17
Ambiguous Figures
The Great Panoramic - Salvadore Dali, 1936
18
Ambiguous Figures
Multiple Figures
2
3
2
2
19
Ambiguous Figures
Mask Concavity
20
Ambiguous Figures
Machs Figure
21
Ambiguous Figures
Schroders Staircase
22
Ambiguous Figures
Oscillating Cubes
23
Ambiguous Figures
Necker Cube
24
Ambiguous Figures
25
Ambiguous Figures
Cube looks like a cube. Equal sides and right an
gles. Eye Perspetive projection Reverse Tople
ss pyramid change of shape
Cube looks distorted, on face smaller than the
other.
Depth is paradoxical Reverse No Change
26
Ambiguous Figures
Cube does not look like a cube.
Eye Near face is same size as far face
Reverse Topless pyramid further face always
looks larger
Necker Cube. No face is front or back by
perspective Depth is paradoxical Reverse No cha
nge
27
Ambiguous Figures
  • Possible views
  • Cube with corner missing
  • Box in corner of room
  • Small cube infront of large cube

3 in 1 Illusion
28
Ambiguous Figures
Cube / Room
  • Possible views
  • 3D Cube
  • Corner of Room
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