This past weekend I was making myself some soup while recovering from a bout of Covid. I was zoning out, looking at the marbling pattern on the marble countertop, and about a six inch diameter section of it appeared to slowly swirl or rotate. The effect lasted many long seconds before wearing off. I thought wow, the Covid must be affecting my brain and causing me to hallucinate! Then I realized that first I had stirred my soup and watched it swirl for several seconds before looking at the marble countertop. I confirmed that was the cause of the illusion when I reproduced it by stirring soup, staring at it for 30 seconds or so, then looking at the countertop. Weird thing is, I stirred my soup in a clockwise motion, but the countertop looked like it was swirling counter-clockwise.
It made me think that my eyes fool me pretty regularly–when stopped in multiple lanes of traffic, out of the corner of my eye I see a car in the adjacent lane start to slowly move forward, but I get the illusion that I am actually drifting backward, and push down harder on the brake that’s already keeping me in place. Or the startle when a figure is in a darkened room, but it’s just, say, a long coat hanging on something-- a classic horror movie staple that has actually happened to me on more than one occasion. And I have to ‘face’ the fact that I experience pareidolia constantly.
One weird one happened a few months ago-- I was binge-watching ‘Lower Decks’ on Paramount+ (for those who don’t know, an animated show in the Star Trek canon) with one eye while doing some other stuff. Without me noticing, the last episode of LD finished and the streaming automatically went to ep.1 of “Strange New Worlds”, a live-action Star Trek show. Since I was thinking I was still watching an animated show, I thought “huh, the show switched to a much more realistic animation style for this episode”. It was not all that surprising to me, since I had recently watched a show called “Love, Death and Robots” that featured various anthology stories in very different styles of animation. This illusion persisted for several minutes of half-watching, with me thinking stuff like, wow, the long hair and beard animation effects on the retired Captain Pike are very well-done.
I was once at a church service with an Ecuadoran friend, and one of the songs they were singing, they were alternating English and Spanish on the verses. When the Spanish verse started, he leaned over to me and said “Suddenly I understand English so much more easily!”.
I have a really distinct floater at the moment. The other day I caught sight of it against a light colored wall and thought a tree frog had gotten into the house again.
Best I can do is “glasses off, see something I’m sure is _______, then put glasses back on and see I was wrong.” That happens not-infrequently.
For example, earlier I thought I saw a golf cart going through my back yard. (This is one of those ‘no fences’ neighborhoods with a homeowners’ association that contracts for grass-cutting for all.) But on second glance I saw it was a yard-work company’s little cart, not a golf cart.
Not exactly an optical illusion, I’ll admit. Good topic–I’ll try to think of a better example.
When my brother was in college, he wanted to do a psych experiment to study which way the bed spun when you were drunk and had the bed spins.
When I was growing up, we had a book with all kinds of optical illusions - which line is longer, is it a vase or two faces, etc. A few of them were “stare at this image for a minute, then stare at a blank wall”, and the light squares turned dark and the dark light. I wonder if your soup stirring residual is the same effect.
So many lately! I got new glasses, and I see things out of the corner of my eyes constantly! Like flies or mosquitoes. The trouble is, we get these things in the house all the time, too. The other thing that bugs me (heh!) is a warp - the bottom edge of my glasses causes whatever I’m looking at to look like a bowl. They are transition (no-line) bifocals and I’ve never had them before. Could that cause that phenomenon?
Sometimes small dirt clods or dog kibble on the floor look like bugs or roaches. On closer inspection, I find I’m just a lousy housekeeper!
Pretty good bet. If you drive a long time at high speed and quickly stop, you can often perceive the scenery receding away from you as if you were in reverse while the car is definitely stationary.
IMO the vision system is doing something akin to
I know everything is spinning / moving this way, so to make it easier to understand the details of this moving stuff I’ll turn on an anti-motion filter that offsets the motion so my scene detail recognizers don’t have to chase a moving target.
But when the eyes first shift to a different non-moving scene, the motion filters are still on for a few seconds until the vision system realizes they’re unnecessary. The net effect is your perception is that statioanary stuff is spinning / moving the opposite way.
The car effect is real fleeting unless you’ve been hauling ass in a constricted scene like a single-lane tunnel or narrow road enclosed on both sides and overhead by trees. And doing it for awhile, like many minutes. The spinning soup lasts a lot longer. At least for me. YMVMV (Your moving vision may vary).
Back in junior high, the homeroom teacher was addressing us students one morning. He was standing in front of the blackboard (which was chalk free) holding a large black binder in front of his chest. The binder was the exact shade of black as the chalkboard and when the binder was parallel to the board his chestal region vanished and his head began floating around the room. As good as any green screen effect.
If I walk past my kitchen when the house is dark, the microwave clock numbers reflect off the counter, but in the dark, I can’t see the counter, so it seems that eerie blue light is coming from the bottom of the oven. It freaks me out.
My last job had carpeting on the floor with a pattern of small colorful dots that repeated every one to two feet. Sometimes when you were looking at it and your eyes became a little unfocused, it became one of those MagicEye things where one eye would focus on one dot and the other would focus on it’s identical twin to the right. The net effect was depth perception went out the window and suddenly the floor was two or three feet closer to you than it should be.
It’s called motion aftereffect. It’s related to afterimages, where, after staring at a colorful image for a while, when you look away you see its negative.
I like to do this for fun or as a distraction, if I have a repeating pattern nearby, like wallpaper or a tile pattern. (OK, mathematicians are strange.)
My wife and I went on one of those charter fishing boats. When the boat was putting along (at a decent speed), the water seemed to be flowing towards the bow instead of the stern. Plus, the gray deck paint had many black speckles in it and they seemed to flow towards the stern.
Yup. When I was a kid, one of my amusements was sending a chain-link fence off to infinity.
I also like looking for Moire patterns. You often find them, for instance, when you see an overpass over the freeway that has multiple layers of fences.
One of the most common places I’ve found to do that is in a public bathroom. Any time the walls are tiled in ~1-3" tiles, you can slightly widen your eyes out and “lock on” to adjacent vertical grout lines instead of both eyes pointed at just one line. You may have to stand a little closer or farther than usual to make it work. The more you practice the easier it gets. Once you do get the vergence close, your visual system will lock-on and you can sustain this for as long as it takes to finish your business standing there.
I find when I spread eyes like that depth perception is exaggerated, not suppressed. Sort of like the overdone 3D-ness of the old ViewMaster stereo-optical discs. Very interesting.
Weird body tricks are fun.
And thanks for the cite; I didn’t know the name of the effect.
This happens to me inadvertently, but I find that it affects the pressure level. I.e., my visual system has some kind of feedback mechanism to the bilge pumps, and I run the risk of overshooting or undershooting the mark. It’s not a huge deal at a urinal, but overpressurization causes more splatter than I’d prefer.
Is this why, when you spin around and around for a bit and then stop, your eyes exhibit horizontal nystagmus (or something like it) for several seconds?
or does that have something to do with what’s going on in your inner ear?
I want to say counterclockwise. Hopefully I don’t get another chance to investigate.
