Dynamic Müller-Lyer Illusion

Prize illusion sarcone

I am very proud that my “Dynamic Müller-Lyer Illusion” won the third prize as best illusion of the year 2017!

As you surely know, the “BEST ILLUSION OF THE YEAR CONTEST” is a yearly competition under the patronage of Scientific American, organized by the Neural Correlate Company (New York, USA).

Müller-Lyer’s illusion proves that a segment can visually appear longer or shorter depending on the sense of the arrow heads at its ends. In what consists my variant? As shown in the animation, the red dot in the middle of the line is equidistant from the other two red dots, although the ends of the line visually appear to alternately stretch and shrink like a rubber band!

The radial version of the illusion is even more impressive:

The perceptual increasing and decreasing of the segments occurs in a very short time. Thus, I suppose it is more a physiological phenomenon, rather than a psychological bias. Our attention seems to be attracted by the receptive field WITHIN the V-shaped arrow heads, causing an illusory inward or outward shift of the ends of the line.

Oddly enough, the illusion seems to work even though the two segments that form the line aren’t straight, as shown in the animation below.

Muller Lyer Sinus

A lot of compelling and artistic variants can be created with my dynamic concept! (see further below) The vertical color segments of the pattern below are always the same length. In this version comes into play the “neon color spreading” effect… (Watch an intriguing musical variant on my Youtube channel)
Müller-Lyer waves
Below is a smoother version with higher frame rate, some more lines, and more acute angles; it also involves a striking dynamic “neon color spreading” effect.
And what about this anthropomorphic version?
Muller-lyer anthropomorphic

zig zag muller lyer

This variant works like an hypnotic kaleidoscope… The different sizes of the arrows give the overall pattern a more spatial depth, like a tunnel effect.

Many geometric illusions involve V-shaped lines… You can see similar effects in fabric patterns (Zöllner illusion), in the moon illusion (the moon appears larger in the horizon due to Ponzo illusion effect), in the distribution of a line in a closed space (Sander’s parallelogram), etc. A similar illusory effect applies also to time perception: time that is filled with activities (compacted line with arrow heads pointing outside) seems shorter than empty time, when we have nothing to do (unwrapped line with arrow heads pointing inside).

How did I discover this dynamic illusion?

Well, I hold many optical illusion workshops around Europe. About two years ago, I presented the Müller-Lyer illusion to children, using a hands-on exhibit of my creation. The exhibit consisted of a simple metal board onto which was painted a line with three red dots: one dot in the middle of the line, and the two other dots at its ends. A sort of clock hand could be pivoted at each dot, to empirically experiment the illusory increasing or decreasing of the segments. To my great surprise, some children played nonstop with the thin revolving hands of the exhibit, mesmerized by the illusory effect. That experience prompted me to create an animated version of the Müller-Lyer illusion.

Some newspapers and blogs where my optical illusion has been featured

Scientific American
Mental Floss
El Pais
Tecna Magazine
Česká televize
Laughing squid
Joachim Wedekind Blog

More ‘Dynamic Müller-Lyer’ variants

Müller-Lyer Circle

Sarcone, Gianni A. “Dynamic Müller-Lyer Illusion.” From Sarcone’s Studio — A Sarcone & Waeber Web Resource. http://giannisarcone.com/Muller_lyer_illusion.html
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