It's well known today that the susceptibility to optical illusions are influenced by the environment: multiple studies with the Müller-Lyer illusion conducted in Zambia proved this environmental influence.

By I wonder if there are some optical illusions that are universal among human.

  • The fact that animals (in particular birds and mammals) are subjects to optical illusions means that at least part of the illusions should be genetically influences.

  • The "perceive the present" hypothesis, should also mean that every human should be subject to at least some illusions.

So my question is: which visual illusions are universal among humans?

To focus the question I would only consider as illusions the one that are related an increase/decrease of the size of an object/subject, or the distance (perspective) or the luminance.

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    $\begingroup$ I don't think we can answer this as written. It would be more amenable to answering if the question was of the form, "Are there people for whom the illusions X, Y and Z do not apply?" $\endgroup$ – Christian Hummeluhr Mar 21 '15 at 19:52
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    $\begingroup$ I don't think that what @ChristianHummeluhr describes is the only option for rewording this question. In particular, I think that "Which sort of visual illusions are believed to be universal across human cultures?" can be a perfectly well-formed question. However, the answer might be "what do you consider an illusion?". For example, is colour an illusion? When I (and as far as I know when people of other cultures) look at my computer screen, I do not see decomposition into intensities of three wavelengths but have the illusion of their combination. $\endgroup$ – Artem Kaznatcheev May 6 '15 at 22:57
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    $\begingroup$ @ArtemKaznatcheev Avoiding having to deconstruct the question with a review of what might be considered an illusion was why I suggested defining a set of illusions, but defining illusions in principle would work for me too. It's certainly not the only way to go about it, of course, just a suggestion. $\endgroup$ – Christian Hummeluhr May 6 '15 at 23:48