Cataracts - A science-y cover of Macklemore’s “Cadillacs” from everyone’s favorite rapping science teacher, Tom McFadden.
If you haven’t heard of Tom, he’s a teacher at The Nueva School in the Bay Area. His students don’t just learn science, they rap it, and they rap it well. Here’s some of their previous hits:
- That’s Metal (“Gas Pedal” cover)
- Watson and Crick vs. Rosalind Franklin rap battle
- All the Salamanders (“Drank” and “All the Single Ladies” cover)
- Alfred Wegener and continental drift
- Black plague vs. Yellow Fever (“Black and Yellow” by Wiz Khalifa)
And Tom’s not just a producer, he’s got rhymes of his own. Don’t miss his first hit, a 50 Cent/Jay-Z-inspired ode to the TCA (Krebs) Cycle: Oxidate it or Love It/Electron to the Next One
Here’s rionhunter's response, I've added my take on this below:
I made a response to this, but unfortunately, tumblr has a way of eating up anything more than 10 lines long, and it got a little lost. So, even though I’m not Hank, I thought I would make a full post explaining the science.
To understand why it’s happening, though, I’m going to have to quickly explain to you what is happening first.
Hopefully we all know that animation (and film) is just a collection of images, flashed in quick succession. The motion that we see, however, is pieced together in our brains, thanks to a thing called ‘persistence of vision’.
Persistence of Vision is caused by the lag in your brain. Seriously.
That brief instant it takes for your brain to understand what it’s seeing is the reason you’re able to watch movies. And we should be thankful for that brief instant.
Light comes into your eyeballs, and it’s crazy hectic data. There’s so much stuff happening all the time everywhere. And while our brains are good, they can’t process everything they’re seeing at light speed. Everything we perceive through our retinas is just light, bouncing off other things. We all know that, but it’s something we often forget.
The brain processes one instant of reality, then a snapshot of the next, and then the next, and so on, and pieces them together to create motion.
This is everything. This is your entire reality. The perception of instances blended together to form a delicious smoothy of senses.
For motion to be consistent, however, what it’s seeing needs to resemble what it was seeing the moment before. For example, for objectX to look like it’s moving, it needs to mostly be where it was the microsecond before, but slightly not.
Basically, you need to think about those ol’ claymations kids make, where the lego slowly edges fowards. You need to take that concept, and apply it to everything you’ve ever known and loved.
If objectX doesn’t overlap where it was before, it’ll look liked it appeared there out of nowhere or a whole new objectX. This is when the illusion of movement is broken. It doesn’t occur in live-action movies or reality as much, because it’s hard to break the illusion of reality when you’re in reality, whereas to create a realistic perception of reality, from nothing, on a screen?
Yeah, a little trickier.
In an industry setting, animators have to create at least 25 frames for every second of footage (FPS). And sometimes, in that 25 frames, animators need to have something move so fast on a frame, that it doesn’t overlap its previous self.
Their solution, as you probably know, is to stretch and contort their object in a way that’s not dissimilar from motion blur with cameras. Especially when you acknowledge that motion blur is everything that’s happening for that 1/25th of a second.
Again, a lot of this is common knowledge, but it’s a matter of how it all pieces together to work.
As you can see here, in figure A, the hotdogs are smoothly sliding out at a consistent speed, which means, if you were to mark each spot they were in every frame, the marks would make a straight line.
The intervals between each marking isn’t very much, because they’re moving quite slowly. The hotdogs are mostly overlapping themselves between each frame.
Now remember that the illusion of movement is all in your brain, where it looks for something that resembled the instant before, and projects trajectory into your concious.
The only reason you’re able to reverse the flow of hotdogs is because they look so similar, and because it’s literally all in your head.
When you make yourself think the flow of hotdogs is going into this fine gentleman’s pants, you’re making yourself believe that, in one frame, hotdogX moves almost a whole hotdog length down, instead of only a little bit of a hotdog length up.
And because it’s almost a whole hotdog length down, in just one frame, the distance of the intervals along the hotdog’s trajectory increases, which means it travels more distance in the same amount of time.
In that one instance of perceived reality (IPR)(Don’t use that anywhere serious, I just made that up), the hotdog moves 9 pixels, instead of 2 (approx.)(I’m not going to count them)
So, to summarize the answer to your question (aka TL:DR);
The reason why the ‘dogs fly into his pants faster is because your brain lag enables you to perceive motion through light (it likes things that look the same). And when things look the same, you can screw with your brain something hardcore.
When you force your brain to see things at different intervals, it can change how you perceive them.
I don’t totally agree with rionhunter's explanation. It's true that persistence of vision and related phenomena of visual perception are responsible for the fact that films and TV don’t look like the series of still frames that they are. But to me, none of that explains the directional perception of the hotdogs or their (apparent) speed.
Today’s films, TV shows, and digitally animated features aim for 24-30 frames per second. Hand-drawn animation like the Disney films of yore used to get away with as little as 12 images per second (each doubled to create a total of 24 frames per second). And yes, they would distort images in between to create a motion-blur type effect.
But the GIF illusion above reminds me more of the spinning dancer illusion than anything else:
Almost instantaneously, that dancer will appear to spin in one direction. A majority of you will see it in a certain direction over the other, but I don’t want to lead the witness, so to speak, by telling you which. Most of you, given enough brain cramping, will be able to reverse the direction of the dancer, just like you reversed the direction of the happy hot dogs (try using your peripheral vision to make it switch).
This initial reaction/reversal trickery is due to the lack of a depth reference in both images. It’s likely that our perceived position below Hot Dog Man tricks our brain into assuming the franks are flying away to the right. And without a reference point that makes the opposite impossible, you can readily make the opposite possible and perceive the hot dogs falling into his pants. Incidentally, you may have heard that your directional preference determines whether you are “right-brained” or “left-brained”, but that’s BS, because brain-sidedness is a BS concept to begin with.
As for their apparent speed? In each of the frames of this GIF, a sausage moves vertically by 12 pixels and horizontally by 4 pixels (I measured). It doesn’t matter which direction you perceive them moving, that’s how far they go in either direction. It’s likely that they appear to move faster when entering his pants (appearing to move down and to the left) because the background is moving to the right. You know how sometimes when you’re stopped at a stoplight and the car next to you will move and you suddenly feel like you’re moving backwards? It’s like that. It’s an illusion of self-motion. On the other hand, when the hotdogs move in the same direction as the drumsticks, the illusion of motion is reduced because the background reference is interpreted differently by your brain. What’s especially cool about this is that the hotdogs move the same distance no matter what, your brain is just doing that thing it always does where it lies to you.
So there ya go John and Hank and everyone else. That’s my take on the hot dog man illusion GIF. Science side … out.
(Hot dog GIF by Lacey Micallef)
Q:Hey Joe, I've just started my senior design project (textile design) and my main inspiration was your "How Bees Can See the Invisible" video. My theme is things in nature that cannot be seen with our naked eye from those ultraviolet altered photos showing us how bees see flowers to other microscopic images. I've gotten a few ideas and sources from your blog but I was wondering if you knew of anything else I could check out if you have the time? If not then thanks for all the inspiration already!
Oh, cool! So, first off, i”m really touched that one of my science videos could inspire some real-life creative work! Secondly, I freakin’ love this idea.
There are so many! Besides the bees and butterflies you mentioned, let’s see, we’ve got birds that can sense or “see” magnetic fields (fish and other animals can do that too, more here). We’ve got the fabled mantis shrimp and its chorus of a dozen photoreceptors (although mantis shrimp vision isn’t quite all it’s cracked up to be). Mantis shrimp can also see circularly polarized light, a skill they share with certain kinds of beetles, who may use it to detect friendly mates who would, to us, remain camouflaged in dense plant growth. Pit vipers can sense infrared like a slithery version of the Predator. There’s a fish with split eyes that can see above and beneath water simultaneously. Many insects have compound eyes, like flies and bees, who knows what that pixelated world looks like? Dung beetles are somehow able to track the stars for navigation, and there’s a whole host of animals with enhanced night vision, often thanks to a special tissue called tapetum lucidum. Dolphins "see" with sonar, and bats use echolocation (there are even moths with echolocation countermeasures!)
Then, of course, we have humans who can see beyond “normal vision.” There’s the still-controversial tetrachromats. Then we have aphakia and ultraviolet vision in humans, like Claude Monet. Even people with color deficiency, such as colorblindness, are seeing things in nature as they can not be seen by those of us with normal vision.
What about our space telescopes, that convert everything from radio waves to microwaves to X-rays into meaningful visual data? What about our various breeds of microscope, able to image proteins and individual atoms?
You know what my favorite part about all this is? Sure, we can’t see it with our own eyes, but for most of the electromagnetic spectrum, we are able to build eyes that can!
I know I’m missing some. Leave your favorites in the comments or reblogs!
Glasses That Can Reverse “Health-Blindness”
If you’re red-green colorblind, then chances are you see nothing, or close to nothing, within the left Ishihara test circle above (you can test yourself here). The image on the right? That’s red-green colorblindness effectively cured with just an inexpensive special pair of glasses.
This type of colorblindness, more common in males than females, results from a deficiency in either the red or green color receptors in the retina, the genes for which are on the X chromosome (hence the higher occurrence in males). If you’re a medical professional, this can be a dangerous condition. This is something that Mark Changizi calls “health-blindness”.
Changizi theorizes that our color vision, particularly our ability to discern reds (something your dog can’t do well), evolved so we could detect health, vigor, and emotions in our fellow primates. Oxygenated hemoglobin happens to reflect red light in wavelengths that fall precisely where our red receptors are most sensitive.
A doctor’s eyes are his or her most powerful tools. Red-green deficient medical personnel are less able to detect conditions like jaundice and low blood oxygenation because they simply don’t have access to the part of the electromagnetic spectrum that they need.
Not any more, it seems. Changizi’s 2ai labs has developed a special lens, called Oxy-Iso, that shifts those wavelengths into the visible. This wasn’t something they set out to do, but colorblind people who tested some of their vision-enhancing technology reported that there was something unexpected going on. While wearing the glasses, which don’t have any active electronics, they report being able to see what was previously invisible to them: pink skin and red blood.
In case you missed that part, these glasses open up an invisible part of the spectrum to colorblind people, and that could save lives. That’s amazing! Science is mighty stuff, eh?
Claude Monet’s Ultraviolet Eye
NEW VIDEO! How the famous painter was a bit like a honeybee, and what that teaches us about the science of vision.
This may be my favorite video of all my videos. I hope you enjoy. Also, I got to play with a Lite-Brite the size of a wall.
The Charles Darwin School For Dogs Who Never Evolved To See Red And Green Good And Want To Do Other Stuff Good Too
Dogs, even the ones termed “sight hounds” or “seeing-eye dogs”, don’t see well. Of course, they make up for this with one of the most masterfully evolved scent-capturing systems ever developed (AKA “their nose”, which is really a biological marvel).
Colin Schultz shares some great links to explanations of dog vision over at Smithsonian Smart News. In short, they see about 20/75 at best, and have only two color receptors in their eye compared to our three, which results in red and green not differentiating into much more than a gray-blah-blurry haze.
I plugged a photo of a red fire hydrant into WolframAlpha’s dog vision simulator to get a sense of what that must be like (although we really can’t tell exactly what it would be like, since we have people brains and they have dog brains and for all kinds of other scientific/philosophical reasons). It’s a good start though.
If you’d like to play with WolframAlpha’s dog vision simulator, head to their site and enter your query like this: “apply dog vision to image of a _______”
In other news, posts like this make me realize how much I miss my puppies while working in San Francisco for the summer :(
Well, that all depends on how you look at it …
Ambiguous image illusions seem to simultaneously point out limitations in our visual system (dependence on shapes, edges and previous experiences in interpreting what’s in our visual field) as well as its flexibility (because in the end, most of us can see both shapes).
Think about that while you explore the young lady/old lady, rabbit/duck and whale/kangaroo illusions above.
I wonder how these work for people who experience “face blindness”, the inability to recognize and identify faces. Radiolab explored that condition previously.
This GIF might break your brain a little:
Take a look at the sequence of images below (I recommend clicking through to enlarge, Tumblr Dashboard folks). Works best if you stare at the dot:
Color? Or black and white?
The rods and cones of your retina respond to the illumination (black-white) and color of a scene, respectively. But that input passes through one key information filter on the way to your visual cortex.
In a sense, your rods and cones take a wavelength survey of the visual field, measuring all the wavelengths they are capable of measuring. It’s the “opponent process” that begins to give color meaning. It’s not only how “red” something is, it’s also how “not green” it is. Likewise, a yellow tulip in the original image from above is intensely “not blue”.
When looking at the “blue” tulips, your blue photoreceptors get fatigued. This creates the illusion of yellow when the blue surplus is taken away.
Ouch. I need to close my eyes.
Beau Lotto: Optical illusions show how we see
One of the best TED talks I’ve seen in recent memory. Sit down and prepare to get a bit of a brain cramp as you are taken through a series of truly awesome optical illusions.
In the process, you will learn a bit about how we perceive the world. In a sense, these tricks show us how our eyes work, but more accurately it shows us how our brains make sense of all that visual information.
You begin with particular wavelengths of light, the purely physical thingness of things. You end with a perception of your surroundings, tricks and all. All the between bits are where the fun lives.
What IS an illusion???