I'll bite. Here's whats up with all the illusions. I wrote in a previous comment that things go viral when each person exposed to a piece of content (sound, im

I'll bite. Here's whats up with all the illusions. I wrote in a previous comment that things go viral when each person exposed to a piece of content (sound, image, whatever) on average exposes it to more than one person. To steal from one of the replies I got, information virality can be understood in the same terms of biological virality Eg the SIR model: https://en.wikipedia.org/wiki/Compartmental_models_in_epidemiology https://en.wikipedia.org/wiki/Compartmental_models_in_epidem... The answer to the question "why is X viral" comes down to "why do people feel compelled to share this". Optical/auditory illusions hit the sweet spot of causing universal disagreement without the disagreement falling along the tired lines of politics, demographics, and other pre-existing tribial lines. The disagreement is both universal and palatable. What do two people do when they have a friendly disagreement? They seek a third opinion. And then the losing side seeks out two more opinions to prove their not crazy. Bam! virality. Eventually it gets to the point where random strangers on the subway are showing you their phone and asking what color is the dress.