[HN Gopher] Mind-Bending Perceptual Illusions (2018)
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       Mind-Bending Perceptual Illusions (2018)
        
       Author : robertwiblin
       Score  : 73 points
       Date   : 2021-08-25 19:04 UTC (3 hours ago)
        
 (HTM) web link (nautil.us)
 (TXT) w3m dump (nautil.us)
        
       | cymon wrote:
       | Number 12 is quite something, it works with anything you look at
       | after staring the center of the top image. I looked at my food
       | and I could see it moving in a very odd manner, went back to
       | image for 15 seconds and looked at the walls, same effect and
       | repeated the same with other stuff and after 10 minutes I feel
       | motion sickness like the one you get after spinning and losing
       | your balance (not everyone gets this I think)
        
         | gpas wrote:
         | It's amazing how well it reproduces how some psychedelics warp
         | vision. Those act on the brain, this tricks the eyes, similar
         | result.
         | 
         | I experience something similar while cycling on trails. If I
         | watch only the road rolling under me for some time and then
         | look at some static object, like a big cloud, it appears to
         | move towards me (or away, can't remember right now).
        
       | the_arun wrote:
       | Very nice collection. All the illusions are due to natural
       | intelligence in the days of artificial intelligence. Brainpower
       | is always a mystery to me.
        
       | cwkoss wrote:
       | I wonder how many of these illusions work in 3D. Might have to
       | take a crack at modelling the rice wave illusion or the cafe wall
       | illusion for 3d printing.
        
       | causality0 wrote:
       | Number 8 has not been created correctly. The line segments
       | actually are being lengthened and shortened because the black
       | segments overlap part of the colored line when they're convex and
       | do not when they're concave. You can see this if you lay the tip
       | of your mouse pointer over them.
        
       | dredmorbius wrote:
       | One of may favourite instances of an optical illusion ever is
       | this short video of a cat pouncing on a sheet of paper on which
       | shows an apparent-motions spirals illusion.
       | 
       | https://yewtu.be/watch?v=S4IHB3qK1KU
       | 
       | It reveals that at least _this_ aspect of feline and human visual
       | perception appears to be similar.
       | 
       | As a means of getting inside a cat's head, it's never failed to
       | fascinate me.
       | 
       | There's another ... _perceptual phenomenon_ is probably a better
       | description than _illusion_ ... contained in an episode of the
       | You Are Not So Smart podcast. In it, a short snippet of noise is
       | played. It sounds completely random. After a cue is heard ... the
       | noise resolves to a comprehensible message.
       | 
       | In my case, I'd started listening to the podcast whilst falling
       | asleep. I don't recall consciously hearing the cue ... but ...
       | when I replayed the podcast the next day, _I could understand the
       | audio clip on the first play_. I 'd "crossed over to the other
       | side* without even consciously hearing the cue.
       | 
       | (I've looked for the episode in the archives listing. I cannot
       | find it though I think it may turn up.)
       | 
       | https://youarenotsosmart.com/all-posts/
        
       | tobr wrote:
       | > 3. Confetti
       | 
       | > The illusion is a vivid demonstration of the fact that we don't
       | directly perceive the colors of objects in the world. Instead,
       | the perceptual system takes an educated "guess," based on the
       | objects' surroundings.
       | 
       | I disagree. E.g. the circles overlapped with green and blue lines
       | look greenish to me, and the circles overlapped with purple and
       | blue look pinkish. If the apparent difference was due to
       | perceiving the lines as a neutral surrounding, the effect should
       | be the opposite: a circle overlapped with green should come
       | across as _less_ green, not more.
       | 
       | I'm pretty sure the effect just comes from half-toning.
        
         | carl_dr wrote:
         | Agreed, I experience exactly the same, and is the weakest
         | (read: most easily understood) example shown.
         | 
         | The others are all very good, I really like that I can
         | understand why I am perceiving them the why I do, but despite
         | of that can't "fix" that perception.
        
         | croes wrote:
         | >If the apparent difference was due to perceiving the lines as
         | a neutral surrounding
         | 
         | That's not how it works.
         | 
         | https://www.livescience.com/confetti-munker-white-optical-il...
         | 
         | Another example
         | 
         | https://www.sciencealert.com/crazy-optical-illusion-makes-yo...
        
       | matsemann wrote:
       | Check out http://illusionoftheyear.com/
       | 
       | It's a yearly contest with people coming up with various stuff.
       | Normally one finds Kokichi Sugihara in the top. I'm a big fan of
       | him after meeting him at a conference (FUN With Algorithms), and
       | made my own attempts on some of his concepts:
       | https://github.com/Matsemann/impossible-objects
        
         | codeulike wrote:
         | https://github.com/Matsemann/impossible-objects
         | 
         | holy crap those gifs with the mirror are completely doing my
         | head in
        
       | JabavuAdams wrote:
       | Wow, that means we really can't trust our eyes / senses for a lot
       | of things! Some people should figure out a way for us to figure
       | out what's true or not, even though we can't see what's true or
       | not. /sarcasm
        
         | dylan604 wrote:
         | That's why eye witnesses aren't as reliable as one might think
        
       | niccl wrote:
       | I've often wondered if there are perceptual illusions for blind
       | people: Maybe a physical cafe wall would feel like the rows
       | weren't parallel.
        
       | john579 wrote:
       | I seem to be immune from most of these illusions. I am not color
       | blind and both my eyes can see fine. It must be something inside
       | my head that's different. I have to read the explanation to
       | understand what other people are seeing.
        
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