— Click icon to select —

full tour stepping feet Motion Induced Blindness Illusion Kinetic Depth Effect, Autokinetic silencing snake snake Pinna-Brelstaff Motion Adaptation, Waterfall Illusion Motion Adaptation, spiralling Roget Illusion Reverse Spoke Illusion wagon-wheel Illusion color wagon-wheel Illusion stroboscopic Illusion Sigma Illusion Eye Jitter Eye Jitter Biological Motion flash lag Ramp Illusion enigma freezing rotation Reverse Phi Illusion radial stepping feet Motion Bounce Illusion Motion Bounce Illusion Tusi Motion Breathing Square Illusion missingFundamentalIcon frequencyDoublingIcon kaleidoscopeIcon Ternus Icon Ternus Icon hermannGridIcon hermannGridCurvedIcon Grid Illusions Moiré Induced Grating Illusion Lozenges COBC Koffka Luminance Illusion Mach Bands Simultaneous Contrast Illusion Pyramid Illusion Munker-White Illusion Adelson Brightness Illusion checkerboard shadow saccadic suppression Contrast Illusion Contrast Illusion contrast gain control Lazy Shadow Vernier & acuity coloured afterimgs coloured afterimgs Colour Fan Benham Top Color Illusion Benham Top unrolled Neon Illusion Neon Illusion Motion at equiluminance Gestalt at equiluminance colour mixture colour matchin colour phi Tilted Table Hering Illusions Poggendorff Illusion Frazer Illusion Tilt Illusion Cafe Wall Illusion Triangle Puzzle Checker Bulge Jastrow IllusionMüller-Lyer Illusion Moon Illusion T illusion sine illusion luminance loomingI Shepard table shepard monster reverspective Necker Cube missing Corner Cube Ames Window silhouette illusion Frankfurter Anamorphosis leaning towers Blind Spot Darwin Illusion Blur Illusion Blur IllusionBlur Illusion Blotted Letter Illusion dalmatian Hidden Bird Rotation Illusions Delboeuf Illusion Ebbinghaus Illusion Dynamic Ebbinghaus Illusion Hollow Face Illusion Face on Mars Thatcher Illusion Ghostly Gaze blurred faces face mosaic

Recognition & Awards

2012-03 Focus 1  | 2  | 3 | 4 (in German)
2011-07 Demand from China so high that my domain was down a day
2009-10 in abc News
2008-09 portrayed by Die ZEIT
2008-04 referenced by NY Times
2007-11 portrayed in fudder
2007-11 daVinci – 3sat
2007-10 Planetarium Freiburg
2007-06 Bayerisches Fernsehen:
Faszination Wissen
2006-09 Dugg, →4.5 million hits/day
2006-08 Focus online
2005-10 PC Magazine: a Top 101 Site
2005-08 BBC Online
2005-08 the Mac Observer
2005-07 Planetarium Freiburg
2005-06 a > 2 million hits/days spike
2005-05 “Image of the week”
by Viperlib
2005-05 > 1 million hits/day
2005-02 “Web Pick” by Yahbooks
2004-12 awardIcon10 cool sites award
2004-11 TV: Discoveries, Sci Chan
2004-11 NSDL Reports Life Sci
2004-10 Highlighted in Science
2004-10 > 500,000 hits/day
2004-09 Wikipedia
2004-03 Nürnberger Nachrichten
2004-03 Brainweek
2004 Yahoo Directory
2003-09 > 100,000 hits/day

Some History / What’s new

2014-08-29 Hidden bird
2014-08-21 New Enigma
2014-08-16 New Induced Grating
2014-08-03 New COBC
2014-06-29 Colour Matching Game
2014-06-08 Colour Phi
2014-05-24 Dynamic Ebbinghaus
2014-04-26 Context & colour
2014-02-05 Benham unrolled
2014-01-01 New Flash Lag
2013-12-26 Wagon-wheel/JavaScript
2013-12-25 Spokes in JavaScript
2013-12-23 Ebbinghaus
2013-12-20 Spiral MAE in JavaScript
2013-12-08 “Palisade” in JavaScript
2013-09-15 Tusi Motion
2013-07-12 Colour Fan
2013-06-05 new Pinna-Brelstaff
2013-04-23 Blind Spot
2013-03-16 improved M. Binding
2013-02-18 Ames Window
2013-02-09 Moiré Patterns
2013-02-03 snake ad lib: ØFlash
2013-01-19 Mach Bands
2012-11-21 Saccadic Suppression
2012-09-19 Contour Adaptation
2012-05-18 Colour Wagon Wheel
2012-05-07 Tilt
2012-05-01 Delboeuf
2012-04-13 Jastrow
2012-04-01 New Stepping Feet
2012-03-07 improved SAM
2012-03-04 improved Café Wall
2011-12-11 Leaning Towers
2011-11-13 Spine Drift
2011-11-13 New technology to replace Flash, namely “Cappucino
2011-05-13 Motion silencing
2011-04-30 Tilted Table
2011-02-19 Impossible waterfall
2011-01-10 Munker Illusion
2010-10-17 Improved Snake ad lib,
all pages hyphenated
2010-07-05 Numerosity
2010-04-15 Anamorphosis
2010-01-03 Shaded diamonds
2009-12-30 Checker Bulge
2009-09-17 SAM
2009-06-08 Breathing Square
2009-04-13 Colour mixing
2009-02-13 Darwin Illusion
2008-11-09 Ternus
2008-10-22 Necker cube
2008-10-03 symmetric silhouette
2008-05-13 reverspectives
2008-02-12 Triangle Puzzle
2008-01-02 Snake ad lib
2007-11-11 Ambiguous Silhouette
2007-10-20 Ghostly Gaze
2007-10-07 Hallucii
2007-07-13 Wagon-wheel
2007-06-08 Added guestbook
2007-03-18 Sine Illusion
2007-02-26 Helm's Kaleidoscope
2007-01-01 Roget's Palisade
2006-12-31 Spiral motion aftereffect
2006-09-24 floating Frankfurter
2006-08-27 Lazy Shadow
2006-07-26 Hidden Bird
2006-06-06 Gestalt & colour
2006-05-22 Freezing Rotation
2006-04-02 Hyperacuity
2006-01-01 cube illusion
2005-11-01 Angry & Smile
2005-10-19 added Section Breaks
2005-10-03 Motion Binding
2005-10-01 Vasarely’s pyramid
2005-08-11 Terror Subterra
2005-07-23 eye jitter
2005-05-22 liac chaser
2005-04-24 Shepard’s table
2005-02-15 switched to CSS
2005-01-01 twisted Hermann grid
2004-12-21 frequency doubling
2004-12-12 Lincoln
2004-12-01 Luminance looming
2004-11-28 Missing fundamental
2004-10-18 Dalmatian
2004-08-16 T-illusion
2004-07-25 COBC
2004-06-25 impossible
2004-05-30 face on Mars
2004-05-16 face-in-beans
2004-04-14 checker shadow
2004-03-26 feet-lin
2004-03-08 Pinna-Brelstaff
2004-02-25 contrast gain
2004-02-08 Flash-Lag
2004-01-30 strobo artifacts
2004-01-03 rotating snake
2003-11-28 reverse phi text
2003-06-22 Poggendorff
2003-05-07 dynam. contrast
2003-04-18 Crossmodal
2003-02.12 no sex…
2003-02-11 Stereokinetics
2002-10-21 Neon
2002-10-12 MIB
2002-10-04 interactive M-W
2002-09-22 Café Wall
2002-09-08 sigma motion
2002-08-27 equiluminance
2002-08-16 Müller-Lyer
2002-08-11 animated Fraser
2002-06-28 White's illusion
2002-06-13 Adelson’s plaid
2001-06-05 Spoke rotation
1999-06-15 Hollow face
1997-04-13 First installment



  Optical Illusions & Visual Phenomena

112 of them – by Michael Bach ()

[other languages: Bulgarian, German, Russian]

Optical illusion are fascinating! They also teach us about our visual perception, and its limitations. Emphasis here is on the beauty of perceptual phenomena, on interactive experiments, and explanation of the visual mechanisms involved – to the degree that they are understood

Befriending mobile devices: >70 interactive demos now without Flash, but requiring up-to-date browser versions.

Don’t let it irk you if you don’t see all the phenomena described. For many illusions, there is a percentage of people with perfectly normal vision who just don’t see it, often for reasons currently unknown.

If you are not a vision scientist, you might find my explanation attempts too highbrow. That is not on purpose, but vision research is not trivial, like any science. So, if the explanation seems gibberish, simply enjoy the phenomenon ;–). More: Bach & Poloschek (2006) Optical Illusions Primer.

»Optical illusion« sounds pejorative, as if exposing a malfunction of the visual system. Rather, I view these phenomena as highlighting particular good adaptations of our visual system to experience with standard viewing situations. These experiences are based on normal visual experiences, and thus under unusual contexts can lead to inappropriate interpretations of a visual scene (=Bayesian interpretation of perception).

Before we delve in, I’d like to express my thanks for your @feedback; any advice is appreciated.

Motion & Time

Luminance & Contrast

Colour

Geometric- & Angle Illusions

Space, 3D & Size Constancy

Cognitive- / Gestalt Effects

Specialties with faces

 

Some sources

 

Donations

 

My bread-and-butter job: Klinik für Augenheilkunde, Universität Freiburg

My involvement with our →local art society

 

 

Thanks to Inga who created new artwork (2005-04) for the ‘eyes’. More from the Bach Family: Maren, Oliver, Christine, Andreas. Occasionally I update my PlusOne Blog.


Many demonstrations require the free Macromedia’s/Adobe’s Flash player . Valid CSS! Valid HTML 4.01!  

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Last update 2014-09-01 by Michael Bach (G+)