Seeing is believing, right? Well it shouldn't be, because we see with our eyes, and our eyes, as science continues to prove, are about as reliable as an inflatable dartboard. Indeed, the two squishy organic cameras and accompanying gray matter whose evidence we use to do pretty much everything are prone to all kinds of fallacies, shortcuts, mistakes, and even outright laziness. The downside to this is that you can never be sure what's real and what's a convenient lie fed to you by the sticky, semi-functional computer that actually makes all of the decisions in your life. On the upside, magic tricks!
There's a great article up on All About Psychology right now, talking about the many ways in which our brains can be tricked into seeing thing that aren't there. The core argument being, of course, that our eyes are crap and our brains are lazy. To wit:
Processing large amounts of information is computationally expensive: if you want to process lots of visual information, you need large brains. But large brains come at a cost, since they require large heads and lots of food to support them. So instead of evolving into creatures with humongous brains, we developed extremely efficient strategies that allow us to prioritise aspects of the environment that are of importance, while ignoring things that are less relevant.
As we've discussed before, a great many magic tricks rely on the idiosyncrasies of human perception to achieve their effects. Some of these tricks exploit the rough-and-ready way our brains process information. Our brains seem to prefer translating visual information into a rough and ready 3D map over providing an accurate view of the world. That's why illusions like the one below don't just look weird, they interfere with our balance in a much more fundamental way.
Our eyes are even worse, rather than truly follow an object in motion, they'll let the brain make a quick estimation of direction and velocity, then call it a day, only really registering the object again if it changes direction or speed. Our brains are so good at truncating this information, it'll sometimes fill in the blanks for us. If we've seen a ball thrown once and are then shown the motion again, more than 50% of us will actually "see" the ball in flight, even though it hasn't been thrown. Ergo: magic.
The article also has some interesting titbits of info about how our brains measure time (spoiler: they're bad at it) and how we're all constantly trying to see the future (again, bad). It's a very interesting piece.