Perceptual Illusions

Here are some more good ones:

https://www.sciencealert.com/this-3d-optical-illusion-will-m...

... which embeds my all-time favorite ("Ambiguous Cylinder")

https://youtu.be/oWfFco7K9v8

Those are particularly good examples of optical illusions. Normally these sort of articles are disappointing, but I'd not seen many of those before. Very tempted to order one of those mugs.

I used to have a printout of https://www.michaelbach.de/ot/mot-snakes/index.html over my desk. People got so freaked out by a piece of paper "moving" that there were people who literally refused to go to my desk. :-)

I was recently investigating a CSS shadow issue that looked like an uneven shadow across the bottom of an element that had a lighter section and a darker section, but it turned out to be illusion #6! I had to do the color picker method on the shadow to convince myself, and even after I had convinced myself by drawing a single color line in between, my eyes were still fooled. Very tricky!

Studying electrical engineering I've learned an important concept: Everything is relative. Ex: to measure the voltage, we need a reference to measure it against. I think the brain works very much the same way. Every perception of reality is processed with respect to some reference.

I've often described colour blindness as an optical illusion, and that confetti illusion is exactly what I have in mind. Peanut better has a green lid and green label which makes the slightly ambiguous brown look green. Or the walk symbol at a cross walk - usually a light is white so I just assume that walk symbol is also white (even though I now know it's green). Or the statue of liberty - it's a big rock so I assume grey, even though I know it's green. However when any of these are looked at in isolation, it's clear what their correct colours are.

These are great and many were new to me.

Instead of #6, the one involving moving the square from the light to dark side, I prefer the static Checker Shadow illusion[1], using the same priciple. The problem with involving electronics in it is that there always is suspicion that the machine is playing the trick instead of just your visual system.

[1] https://en.m.wikipedia.org/wiki/Checker_shadow_illusion

These are cool. FYI some of the images are displayed at the wrong aspect ratio. The final example in particular is pretty squished, I recommend opening the image in its own tab.

I’m always annoyed by the arrow length trick. This article calls it the “Müller-Lyer” illusion. The problem is inconsistent line caps and the joints overlapping means that the size of the line actually is changing a little. As a result, I’m not sure whether there’s an optical illusion involved or not, and, if there is, this is a poor way of demonstrating it.

This is a timely post, considering the 2018 Best Illusion of the Year Contest has just posted http://illusionoftheyear.com/cat/top-10-finalists/2018/ .

These are awesome! I studied cognitive psych and psychobiology at UVA in the mid 90's, and my favorite class was a seminar on perception. Illusions are a great tool for learning how our visual system works. Also, they're really cool.

Seems like the human perceptual system is easily hacked. I wonder how close we can get to an actual Snow Crash bitmap?

whoa, turns out some people with autism, schizophrenia and transgenderism aren't affected as much by these illusions if at all.

Still can’t subscribe to the print edition!