A Germanpsychologistnamed Franz Carl Muller-Lyer created the illusion in 1889.
What Do You See?
In the top half of the image above, which line looks like its the longest?
Fibonacci / Wikimedia Commons / (CC BY-SA 3.0)
The line with the arrow fins pointing inward looks like it’s shorter.
Here are a few theories theyve come up with.
By looking at how we perceive illusions, we can learn more about how our brains andperceptual processeswork.
In most cases, size constancy lets us perceive objects in a stable way by taking distance into account.
When we apply this same principle to two-dimensional objects, Gregory suggests that errors can crop up.
In this case, there are no depth cues but the illusion still occurs.
It has also been shown that the illusion can occur when viewing three-dimensional objects.
The Depth Cue Explanation
Depth plays an important role in our ability to judge distance.
This depth cue leads us to see the line as being further away and therefore shorter.
This depth cue leads us to believe that the line is closer and therefore longer.
This also suggests that perhaps optical illusions represent what our brains like to see.
Does Everyone See the Muller-Lyer Illusion?
And another cool thing?
In 2021, Professor Susan Goldin-Meadow from the University of Chicago did a study using the Muller-Lyer illusion.
And using it struck me as an ideal way to ask this question about where gestures come from.
I thought they were tied to language because gestures and speech are so well integrated.
But now we have evidence that gestures may also stem from action.
2014;8:856. doi:10.3389/fnhum.2014.00856
Morikawa K.An program of the Muller-Lyer illusion.Perception.
Princeton University Press; 2015.
Amsterdam: North-Holland; 1989.
Proulx MJ, Green M.Does apparent size capture attention in visual search?
Evidence from the Muller-Lyer illusion.Journal of Vision.
2011;11(13):21-21. doi:10.1167/11.13.21.
2005;102(4):1234-1239. doi:10.1073/pnas.0409314102
Rivers 1901:The measurement of visual illusionRep.
Ass., p. 818
Segall, M. H., Campbell, D. T., & Herskovits, M. J.
(1966).The influence of culture on visual perception.Bobbs-Merrill.
Ahluwalia A.An intra-cultural investigation of susceptibility to ‘perspective’ and ‘non-perspective’ spatial illusions.Br J Psychol.
1971;6(3):199-207. doi:https://doi.org/10.1080/00207597108246683
University of Chicago.What size is an object?
Your description might depend on your intentions.
Prinzmetal W, Gettleman L.Vertical-horizontal illusion: one eye is better than two.Percept Psychophys.
1993;53(1):81-88. doi:10.3758/bf03211717
APA Dictionary of Psychology.Ponzo illusion.
