Moving Illusions

Hey, Vsauce. Michael here.

This is a completely still image, but as your eye reads what I'm saying and jumps from word to word, the paragraph will appear to slightly, just subtly, wave and boil. The allusion is called anomalous motion. It's neat. But to say it's fun is tautology because the word illusion literally means to have fun, to mock, to play with.

But illusions aren't just fun and games. They also teach us about our brains. Anomalous motion, for instance, demonstrates that our brains process things at different rates and piece by piece. After a saccade, a quick eye movement, higher contrast elements are perceived sooner than lower contrast ones. When arranged in just the right way, this delay is exploited and your visual system only has one explanation. Low contrast parts of the image didn't get processed later because this myelinated machine is wrong, but rather because the image itself must be moving.

Akiyoshi Kitaoka's brilliant "Out of Focus" causes nearby neurons to disagree about the little slices they each detect. Some see big changes after a saccade, and some see hardly any. This makes it difficult for our brains to calculate and factor in the effect of our own eye movements, so the image itself appears to be moving.

But illusions aren't just about moving. They can also be moving, poignant, significant, practical. They can mean the difference between life and death, like in nature or during World War I, as dazzle paint on ships. This form of camouflage doesn't conceal the object but rather makes it difficult for an enemy to ascertain its prey's true shape and thus where it's heading or how fast it's going.

In 1955, the Soviet Union displayed their new Bison and Bear long-range bombers at an air show. It looked like they had a lot. Afraid of falling behind, the US ramped up production on their own B-52 bomber. But the whole thing was an illusion. In the Soviet's film of the air show, the same few planes had been flown past the camera multiple times in formations that gave the illusion of them having more bombers than they really did.

By the end of the 1950s, the Soviet Union only had about 150 long-range bombers, whereas the Americans, fooled by the illusion, had built nearly 2,000 at a cost of 900 million dollars. Architecture is full of examples of real-world practical optical illusions. My favorite are Disney castles. They appear huge, but it's forced perspective—a lie. The tops appear further away from us because they are actually quite tiny.

Illusions also tell us about ourselves culturally. The Müller-Lyer illusion is classic. The horizontal lines are all the same length, but the bottom ones appear longer to people from Western cultures, familiar with our rules of perspective and man-made straight lines. However, bushmen from Southern Africa and tribespeople from northern Angola or the Ivory Coast aren't fooled at all.

Akiyoshi Kitaoka is using optical illusions to discover glaucoma earlier than current techniques can. And anamorphic illusions are used to save lives. They look weird from any perspective but one, from which they seem to pop out defying the environment's actual shape. Hoping to remind drivers to always pay attention, traffic safety organizations in West Vancouver, Canada, placed a skewed decal on the road. From the right perspective, the perspective of the driver in this case, it becomes a 3D illusion of a child you are about to hit. Slow down.

Brusspub has made some incredible examples of the 3D effect such illusions can happen. This object? Just an anamorphic projection. Anamorphic illusions have also been used to safely practice political dissent. In 1746, supporters of the Stuart claim to the British throne had to be quiet about it. It was treasonous. So, sympathizers served things on trays that looked like this.

Innocuous enough until only supporters were around. And it was safe for someone to place a reflective goblet or cylinder on the tray, revealing the tray's anamorphic secret: a hidden portrait of their illicit love, Charles Edward Stuart himself. The Encyclopedia Titanica lists descriptions of everybody recovered from the Titanic. It's quite macabre. Why was the iceberg not seen until it was too late?

And why did the nearest ship—the Californian—not come to the Titanic's rescue sooner? Tragic questions whose answers might be optical illusions. The Titanic was sailing through conditions perfect for mirages. This theory points out that the Titanic sank at the border of the warmer Gulf Stream and the frigid Labrador Current, where the normal case of cooler air at higher altitudes was inverted—a thermal inversion.

Now, because the temperature of air affects its index of refraction, a thermal inversion means light bending in typical ways. If light reaches the eye from higher up than usual, objects can appear to float. Seriously. Like this ship off the coast of Australia. A thermal inversion can also render objects completely unrecognizable, hidden within a haze, like this ship or like an iceberg. Or a sinking ship in need of help.

The Delboeuf illusion may be causing teeth to split and crack more often than they should when dentists drill holes in them. Doctor Robert O'Shea observed eight practicing dentists and found that they were all drilling holes that were too big, even though they knew the correct size to be drilling. Why? Well, it may be the same reason people eat more food when they're given a bigger plate. Objects appear smaller when enclosed by larger areas.

Holes of the same size may appear different sizes on bigger teeth. Dentists may be deciding that correctly sized holes drilled in the teeth need to be made larger, not because they do, but because perception is a tricky thing. Illusions affect not only big ships and teeth but also your future.

The End of History Illusion is our tendency to think of ourselves today as somehow done. Sure. I went through a lot of personal growth and changes in taste in the past, but today, who I am now, this is pretty much the final me. But that's not true. Studies have consistently shown that people underestimate just how different they will be, say, 10 years in the future, even though they can easily point out how much they've changed since 10 years ago.

I like how Daniel Tomasulo puts it: "We believe we are going to live, love, and long for where, who, and what we are thinking about right now. But the research says it just ain't so. This too is a transient state." Yogi Berra put it even more succinctly: "The future ain't what it used to be." Their advice is don't imagine your future. Look at other people and their experiences instead, take their advice. Your imagination is just that, their experiences are actual data.

Well, of course, it's not that simple. Which brings us to our final illusion: The illusion of control. Named by psychologist Ellen Langer, it's our tendency to believe we control the outcomes of things. We demonstrably don't. It can help motivate us to not give up, and in healthy people at a healthy level, it is optimistic self-appraisal. But it's a lie.

In one study, traders in the City of London's investment banks were shown a graph of a real-time stock price and given three buttons that secretly didn't do anything to affect the price. But they were told the buttons might have an effect—try them out, see what you can do. Afterwards, the traders were asked to rate how much they felt they had been able to control the stock price with the useless buttons.

And it turns out the traders who reported the greatest sense of control over the stock price were the ones who scored lowest on risk management tests and, in the real world, contributed the least to their company's profits and, in terms of salary, made the least money. It's kind of a bummer. The illusion of control is a nice feeling, but sometimes it's fine; sometimes it even pays handsomely to admit you don't have control.

And as always, thanks for watching.