Physics 1230: Light and Color
Ivan I. Smalyukh, Instructor
Office: Gamow Tower, F-521
Email:
ivan.smalyukh@colorado.edu
Phone: 303-492-7277
Lectures:
Tuesdays & Thursdays,
3:30 PM - 4:45 PM
Office hours:
Mondays & Fridays,
3:30 PM – 4:30 PM
TA: Jhih-An Yang
jhihan.yang@colorado.edu
Class # 19
Midterm Exam #2
• HW5, Due Tuesday, Nov 8
• Chapter 7 – finish today
•Exam Overview Today/Thursday (Nov 3)
•Exam: Nov. 10, Thursday
•Science lab tour – to be announced;
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Interesting collective behavior 3: Sensitive to a
MOVING World. Time and motion important.
Fatigue: prolonged stimulation (staring at a lamp)
causes a weaker response and a negative
afterimage.
Successive lightness contrast: a gray object looks
darker after looking at white.
Positive afterimage: We see a flash as a bright
spot after it has gone away. Over stimulated
nerves keep firing.
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Fatigue and Involuntary eye movement
Eye movement moves the image around so that
new areas are stimulated.
Without eye movement, images fade. This has
been verified by experiments that fix the image
on the retina.
Eye movement causes wavy lines to appear as
though in motion, because the afterimage
interferes with the moved image.
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The eye is moving all the time. It corrects for motion…
IF there are edges, but not if edges are absent.
The only difference between the center and
edge is the lack of any feature to “focus” on.
http://www.michaelbach.de/ot/mot_eyeJitter/index.html
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Other illusions
There are many optical illusions with varying
explanations. Many are poorly understood.
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Are the blue shades the same?
Lateral inhibition cannot explain this!
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Lateral inhibition alone does not explain this effect, the Munker-White illusion.
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http://www.newworldencyclopedia.org/entry/Muller-Lyer_illusion
Müller-Lyer illusion
Which arrow is longer?
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http://www.michaelbach.de/ot/index.html
Müller-Lyer illusion
This is the back corner of a room, it is
further away, hence it must be larger.
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Big Moon Illusion
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What you remember.
Actual
Frankfurter illusion
While focused on the background, hold your two index fingers
horizontally in front of your eyes, not touching. A piece of finger will
appear to float in space.
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http://www.michaelbach.de/ot/sze_Frankfurter/index.html
Are the lines straight?
Hering Illusion
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Does the square have straight sides?
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http://www.michaelbach.de/ot/ang_hering/index.html
Does the square have straight sides?
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Poggendorff Illusion
Are the lines
continuous and
straight “behind”
the yellow columns?
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http://www.michaelbach.de/ot/ang_poggendorff/index.html
Poggendorff Illusion
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http://www.michaelbach.de/ot/ang_poggendorff/index.html
Art that mimics 3-d.
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Motion after effect
Motion channel, keeps firing after watching a
moving object, causing motion aftereffect.
http://www.michaelbach.de/ot/mot_adaptSpiral/index.html
The following are from Akiyoshi Kitaoka
Department of Psychology, Ritsumeikan University, Kyoto, Japan:
http://www.psy.ritsumei.ac.jp/~akitaoka/saishin27e.html
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Motion illusion (A. Kitaoka)
Note that each green circle is rotated slightly from its neighbor.
As your eye jumps around, it sees the circles rotation.
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Are the ropes tangled?
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from Akiyoshi Kitaoka
Motion illusion (Kitaoka)
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Motion illusion (Kitaoka)
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Snakes - Akiyoshi Kitaoka
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Dead Snakes - Akiyoshi Kitaoka
Motion effects from Michael Bach’s web page
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Silhouette illusion
Motion induced blindness
Motion aftereffect (Waterfall illusion)
Spiral aftereffect (motion channel activated)
Breathing square
http://www.michaelbach.de/ot/index.html
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