Visual Phenomena & Optical Illusions (original) (raw)

Optical illusions don’t “trick the eye”, nor “fool the brain”, nor reveal that “our brain sucks”, … but are fascinating!

They also teach us about our visual perception and its limitations. My selection here emphazises beauty and interactive experiments; I also attempt explanations of the underlying visual mechanisms where possible. Returning visitor? Check →here for History/News.

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

If you are not a vision scientist, you might find my explanations too highbrow. That is not on purpose, but vision research simply is not trivial, like any science. So, if an explanation seems gibberish, simply enjoy the phenomenon 😉.

What do illusions reveal about my personality?

Nothing! While the web is full of claims that your personality (right- or left brain dominated, intro- vs. extroverted, stressed or sublime, or whatnot…) can be deduced from your ability to see some given illusion or which variant for bistable ones. However, there is no reliable scientific data that suggests this. That’s just click-baiting BS. There is some influence of age, though – but you don’t need illusions to know your age… So: 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 don’t see them, mostly for reasons currently unknown.

More material

Bach & Poloschek (2006) Optical Illusions Primer (PDF, 2 pages from ACNR); on the programming: Bach 2014 (paywalled, contact me for a PDF).

Book (in German): “… Täuschungen … Sehphänomene”