Polishing holograms in auto paint… I thought I was hallucinating. Strange “shapes” 6-12 inches inside the panels when the light hits them.
I did some research, very common problem with auto detailers…I understand schools use scratch holograms to teach students the principles of holograms. Looks fun too.
The important question is, if you are in Canberra, does it still spin counterclockwise?
I’m familiar with all these optical illusions, and I’ve added a new one in the past couple of years: I now have a wrinkled retina in my left eye, so if I focus on straight lines using that eye, they look very wavy. I keep finding myself being critical of the job our tiler did in the shower and then realizing that it’s just my eye.
I once made a pool cue disappear from my sight.
It was lying on the otherwise empty table, and in pure freak coincidence was at just the right angle to align with my blind spot. All I saw was an empty green pool table. Then I turned my head a fraction and a pool cue leapt into being. Took me a little while but I got myself lined up again and poof it disappeared. Here, gone, here, gone with just a minuscule move of the head.
I knew of course that blind spots existed and I’d done the thing with the small cross and dot on a piece of paper near my head. But this was a c.1.5m pool cue lying across a table about 2m away. I wouldn’t have said it was possible.
I too discovered the real-world “Magic Eye” effects but the place that kicked it off for me was a graveyard at a historical site. I was focusing on the gravestones from behind a regularly-staked fence when my focus aligned just right to bring the stakes into alignment with each other, and when I moved the focus “stuck”.
You can easily observe this effect by tuning to any news station with a text crawl at the bottom of the screen and focusing on reading the crawl for a minute or three, then looking at any plain surface.
Related to chromatic adaptation, the way our eye (or more accurately, our brain) perceives an object as being the same color despite differences in light intensity or tint. Despite the fact that it can be used to trick our eyes, it’s a feature, not a bug. This is my favorite optical illusion exploiting the afterimage effect– using it to make us see a black and white image as full color.
And then of course there’s the famous chessboard illusion. I was always fascinated with Oliver Sacks’ studies on people with brain injuries, and what it revealed about how the brain works. Like ‘The Case of the Colorblind Painter’, where the subject suffers a brain injury that leaves him not only completely colorblind, but unable to use chromatic adaptation to process what he sees in different lighting. He wouldn’t be fooled by the chessboard illusion-- he’d probably clearly see squares A and B as the same color. But that’s a bug, not a feature.
Good explanatory/demo video here (12 minutes):
I maintain that the “shadow illusion” is not an illusion, but the brain correctly perceiving that the surfaces would have the same color were it not for the shadow.
If you saw a paragraph written in a “ransom note” style, consisting of wildly varying fonts and sizes for the letters, then, despite the fact that each letter “a”, for instance, looks quite different from each other letter “a”, it would not be an “illusion” when your mind correctly perceives that they are all "a"s. Thus, a surface can correctly be perceived as having a similar property to other surfaces despite having more or less light shining on it.
That is a very cool video, thanks!
If you’re referring to the ‘chessboard illusion’ I wrote about a few posts up, that’s precisely the point I was trying to make. Yes, it’s very much a way for the brain to perceive visual constancy of an object despite seeing it in different types of lighting. Though it can be exploited, as in the chessboard illusion, it’s a very necessary visual adaptation.
Hopefully this isn’t too off topic, but can I share some audible illusions too?
This one is super common, like daily basis - sometimes if I am doing something that creates a lot of white noise (washing dishes, vacuuming, working in my office when the fish tank water level is low and there’s a lot of splashing, etc) I’ll be convinced that I can hear my wife calling me, or my kid crying, or the dog barking - something that requires my attention.
Sure, I find audio illusions fascinating as well!
Mrs. Solost and I recently watched an episode of an NBC show called ‘The Irrational’ that concerned a plane crash where the pilot was going to be blamed for the crash because the black box recording made it sound like he said a phrase that indicated he intentionally crashed the plane. But the main protagonist character of the show demonstrated how easy it is to mishear spoken dialogue when prompted to expect certain phrases. I think this is, or is related, to the McGurk effect, in which what we see affects what we hear.
This happens to me quite often. I’ll be in my car stopped in a turn (arrow light) lane (facing up a hill). The lane next to me gets a green light and starts to move. I get the sensation that my car is moving backwards down the hill on its own! Before I realize that it’s just an illusion, I stomp on my brake as hard as I can. For a split second, it’s terrifying!
One that I am afflicted with, especially at night while driving, is lighted signs that have both red and blue lights. While they are physically in the same plane, my eyes see the blue light standing much closer to me than the red light appears. Can be disconcerting.
Been there…
A similar story that my dad once told me was a friend of his who was up on a tall ladder doing some work to the outside of a house. He made the mistake of looking up at the sky, and some moving clouds gave him the distinct feeling that the ladder was falling backwards. After he climbed down off the ladder he threw up, it freaked him out so much.
I suppose the key thing is to look at the cue from such an angle that you’re viewing it mostly end-on, not transversely. So its total angular extent is less than your blind spot’s extent. Which spot is a good deal bigger than we commonly assume it is.
Your post reminded me of one of mine. Not the same cause, but a similar effect.
The bedroom in my prior residence had white ceilings and a typical 5-bladed white ceiling fan that was usually running at a slow setting. The rest of the room setup created a gradient of illumination from semi-bright near the windows to semi-dim near the opposite wall.
When the fan was turning slowly enough that the blades could be seen individually, each blade would wink out of then back into existence at one point in the rotation when its color and lighting exactly matched the ceiling. The effect was very reliable. And somehow fascinating to watch. Knowing the “why” did nothing to prevent the “what” because all that stuff was happening waay upstream in the subconscious visual processing system.
I get this frequently. I recall an explanation, something like a picket fence illusion where you seem to see something behind the pickets. It’s rather annoying to turn off the noise and hear nothing but silence.
Our sense of vision is easlily deceived. The “fine detail” part of the retina is a small area so the brain simply fills in the outer edges of our field of vision. This is one reason magic tricks work so well on us.
And of course, this is also a feature-not-a-bug. If you’re in an environment with a lot of different sounds, it’s impossible to completely analyze all of the sounds, so we fall back on template matching: If there’s anything in the mess of sounds that matches the template of a sound that we consider important, we’ll still pick out that bit. For you, important templates include your wife calling, your kid crying, or your dog barking. Probably also your own name is an important template for you. But you won’t hear someone calling your wife’s name in white noise, for instance, because that’s not as important a template for you.
Nothing we do is perfect; everything has tradeoffs. The imperfections we have are better than the larger imperfections we would have otherwise.
Yeah, absolutely - it’s the auditory equivalent of seeing faces in rocks and such, I am sure. It can be quite annoying, though!
(Not as annoying as getting eaten by a leopard, I am sure)
