When this curious contraption is switched on, an inner circle of white balls appears to be rolling inside the outer circle, but that's actually not the case at all. Below is a video explaining this circular motion illusion. Learn more about the mathematics behind it, specifically Copernicus’ Theorem, and the ingenious hypocycloid mechanical gear design by Girolamo Cardano (1501-1576) over at The Kid Should See This.
And if shaking your head really fast is, er, problematic, you can also just look at an angle or move away from the screen until the image appears.
Here's an Instructable on how to make your own head-shaking illusions.
(via r/interestingasfuck)
Science Alert claims this illusions mimics time travel in the brain. I think the illusion works, but I saw no dinosaurs. Read the rest
Caltech researchers developed the illusion above to illustrate postdiction, a sensory phenomenon "in which a stimulus that occurs later can retroactively affect our perceptions of an earlier event." From Caltech Matters:
"Illusions are a really interesting window into the brain," says first author Noelle Stiles (PhD '15), a visitor in biology and biological engineering and a postdoctoral scholar–research associate at USC. "By investigating illusions, we can study the brain's decision-making process. For example, how does the brain determine reality with information from multiple senses that is at times noisy and conflicting? The brain uses assumptions about the environment to solve this problem. When these assumptions happen to be wrong, illusions can occur as the brain tries to make the best sense of a confusing situation. We can use these illusions to unveil the underlying inferences that the brain makes...."
Postdictive processing has been demonstrated within individual senses, but this work focuses on how the phenomenon can bridge multiple senses. The key to both of the new illusions is that the audio and visual stimuli occur rapidly, in under 200 milliseconds (one-fifth of a second). The brain, trying to make sense of this barrage of information, synthesizes the stimuli from both senses to determine the experience, using postdiction to do so.
Read more in the researchers' scientific paper: "What you saw is what you will hear: Two new illusions with audiovisual postdictive effects" (PLoS ONE) Read the rest
Get your game on, go play. (AsapSCIENCE)
Spatial frequency means how often things change in space. High spatial frequency changes means lots of small detail. Spatial frequency is surprisingly important to our visual system – lots of basic features of the visual world, like orientation or motion, are processed first according to which spatial frequency the information is available at...
Spatial frequency is also why, when you’re flying over the ocean, you can see waves which appear not to move. Although your vision is sensitive enough to see the wave, the motion sensitive part of your visual system isn’t as good at the fine spatial frequencies – which creates a natural illusion of static waves.
See Einstein below? Now go a few steps back from your screen and look again:
Vsauce3's Jake Roper reveals the wondrous perceptual paradoxes of "impossible objects" from Escher's cube to the Penrose triangle.
(via Laughing Squid)
The folks at Snarkitecture collaborated with the Portuguese design firm UVA to create the "Slip Chair", which looks like it's tipping over, but is safe to sit in.
Or so they say! Me, I'd like to see a picture of someone actually sitting in one. But for now I'll take their word, as they write on the UVA site ....
Slip Chair is a wooden chair that appears to be sinking into the ground. As it may seem unusable at first, the wooden frame is even out with a tapered stone and a functional surface for sitting is provided. The apparently opposed elements of the chair are counterbalanced through the monolithic volume of the stone. The chair revolves upon two axes and the suggested unsteadiness of the sliding forms conceals the complete stability of Slip.
(Picture via UVA) Read the rest
What does this DeWalt knife, posted to the "midly interesting" subreddit by turltlecam_son, look like?
a) a chicken b) a unicorn c) a fish d) a knife Read the rest
Jonathan Harris shows you how to draw (and cut) your way to this floating cube illusion. His YouTube channel has many more drawing illusions like it.
Previously in floating cube illusions: cool floating cube illusion. Read the rest
I could watch this all day.
Artist Geoffroy Amelot created this Lego-centric replica of Vincent Van Gogh’s famous self-portrait. Read the rest
The winners in this year's Illusion of the Year contest (previously) are all cool, but it took me a minute to figure out what was going on with the grand prize winner, Mathew T. Harrison and Gideon P. Caplovitz's "Motion Integration Unleashed: New Tricks for an Old Dog." Read the rest
Can you spot the baby in this image? Researchers at the Universities of Cardiff and Cambridge found that volunteers who showed early signs of psychosis were much better at recognizing the baby than a group of people who did not have psychosis.
Can't see the baby? Good for you! See the original photo.
[via]
There's more to phonology than just sound. In this video, several audio illusions reveal just how much we hear is influenced by what we see. Read the rest
WHYY's The Pulse radio show visited The Franklin Institute's new exhibition "Your Brain" where chief bioscientist Jayatri Das demonstrated an incredible audio illusion. Read the rest
This is the winner of the "2014 Best Illusion of the Year Contest;" below is a description and video of the second and third prize winners.
Above:
Christopher D. Blair, Gideon P. Caplovitz, and Ryan E.B. Mruczek University of Nevada Reno, USA, USA The Dynamic Ebbinghaus takes a classic, static size illusion and transforms it into a dynamic, moving display. A central circle, which stays the same size, appears to change size when it is surrounded by a set of circles that grow and shrink over time. Interestingly, this effect is relatively weak when looking directly at a stationary central circle. But if you look away from the central circle or move your eyes, or if the entire stimulus move across the screen, then the illusory effect is surprisingly strong -- at least twice as large as the classic, static Ebbinghaus illusion.
Above:
Read the restMark Vergeer, Stuart Anstis, and Rob van Lier University of Leuven, UC San Diego, Radboud University Nijmegen, The Netherlands
In this visual illusion one colored image can lead to completely different color impressions. The impression depend on the grey scale transparent image that is presented on top of the colored image. The 2 colored images on the left and the right are exactly the same, constructed from a combination of the color profile of the forrest picture and the Manhattan skyline picture. The grey scale image that is presented on top of this colored image reinforces the colors that are congruent with the the gray scale image and inhibits incongruent colors.
