What is an Illusion Too?
Robert Ausbourne

The eyes are not responsible when the mind does the seeing.
Publilius Syrus - 100 BC

The Greek philosopher Aristotle named five human senses some 2,000 years ago; sight, hearing, touch, smell, and taste. We have doubled the number since, by adding a sense of balance, of time, of temperature, of pain and a kinesthetic sense. The list is likely to continue to grow, and a sense of humor may still be found.

In any case, we can ignore the other senses and concentrate on the sense of sight, since this discussion is about optical illusions; an optical phenomenon that results in a false or deceptive visual impression.

The definition seems clear enough, let’s see what we have. First of all, it is fitting that the sense of sight should be first on the list. Surly it is the crowning glory of all human senses. In fact, sight is more like an intellect. Nearly half of our brain's energy is devoted to its work. The visual cortex, located near the back of the brain, at the end of the Eye Way Hwy., is Command central. In this vast sea of living gray our brains decide what we will see.

What we see is an amazing multi-functional, mult-tiered, stereoscopic, 3D steady-cam view, in living color which runs full-time, every minute of our lives. The broadcast is live from Command center. We percieve the broadcast as being in front of our eyes, but it really lives somewhere behind them. Take a glance around the room; tilt your head one way, and then the other. The steady-cam “screen” remains rock-steady, not a jiggle, not a quiver. To run the steady-cam system each of us uses the equivalent processing power of all the super computers in the world combined.

We, our conscious selves are totally blind. Our eyes, having no will of their own, and despite being of a complex nature, are just organs. They follow our directions, collect data and percieve nothing. The movie of life that we see is broadcast from Command center. The show we see is grand, and we are left to make of it what we can. One lingering glance at a spring marigold tells us that the system works beautifully.

The visual cortex crunches raw data streaming in along the Eye Way Hwy., and has access to everything else in the human mainframe. We don't talk to the cortex; we listen. Pictures percolate into our consciousness about one 10th of a second after we view a scene. The tiny delay is important to how and what we see. The movie of life endeavors to accurately depict what is beyond our eyes, but the view is richly marinated in our every thought, our deepest emotions, all our memories, knowledge, quirks, and foibles.

New research has shown that the brain compensates for the one 10th of a second delay in our steady-cam view by looking into the future!  It doesn't do us any good to see everything one 10th of second late;  we need to see stuff now.  What if a chucked rock is speeding towards your head?  You need to duck in time to prevent a nasty knock on the noggin.  The brain calculates the path of the rock and shows you where the rock will be in the next 10th of a second.  It does this constantly, for every fluttering leaf and tennis serve we see.  Despite the built-in delay between sight and perception we always view moving objects in the current now.

Ah ha,” I hear you thinking, “I know where this is going. The visual cortex is very complex, prone to visual errors, and sometimes deceptive. That’s what creates optical illusions.

The visual cortex never lies, and is incapable of deception. Suppose you look at a tree and the visual cortex reports, “That’s a candy cane.” If the cortex tells you to do so; you will see a candy cane. This behavior is considered delusional. You and your sense of sight would soon end up in a rubber room taking pills from a plastic cup. While we can, and often do lie to ourselves and to others, a healthy visual cortex, operating within normal parameters prevents delusions by never lying.

The truthful and loyal visual cortex shows us a true movie of life based on a personal reality; which is made up of an enormous pile of everything we know, feel and remember. Even so, much of reality is shared experience. So much so that a group of us can sit in a room, each in a different location, each with a different point-of-view; and quickly create an accurate 3D map of the room which is both personal and common to all; a truly formidable collective talent. Take that, 3D Space Monsters!

We tackle and solve thousands of visual paradoxes every day, such as “This room is really square ; this wall is not really darker, only in shadow; this border stops one color and begins another; this line is straight and ends here; those telephone poles aren't getting smaller, some are farther away.” The list is endless. We puzzle our way through so many optical illusions, so often that we ignore them as…well, as being normal. A blizzard of spatial problems buffets our brains always; a price we pay for living in a 3D universe.
So what is an optical illusion? An optical illusion is an error issued by Command Central. Actually, it is less like an error, and more like an innocent assumption.  While it cannot lie, the cortex can assume like a champion. “If it looks like a duck and quacks like a duck, it probably is a duck.” What the cortex assumes; we see. Assumptive illusions probably happen more often than we realize, and are often ignored. It is easy enough to trick ourselves; scientists do it all the time.

We trick our senses for good and noble purpose; scientific research. Because optical illusions are come by honestly they pose no threat to us or our sanity, and they help us to understand, and illustrate how the brain works. Optical illusions are similar to the many visual paradoxes we see and solve everyday of our lives. They are new visual puzzles to solve.

With dazzling colors, powerful textures, light and shadows, influential shapes and strange patterns we attempt to fathom the workings of the old cabeza. Illusions are designed to present Command center with inventive paradoxes in order to force a different assumption than the one expected. "If I put a bold circle next to a line, will you assume the line is bent?" By gosh, it works. That is an optical illusion!

There is an excellent assumptive distortion illusion here on the web site; The Hering to Wundt Illusion. Before you run off to check it out; keep in mind what is happening. The moveable red lines are never really bent. We have no choice but to “see” them as bent because the visual cortex has been coaxed into assuming they are bent. No amount of Zen-like concentration will straighten the red lines within these illusions.

One current and most popular explanation of why illusions work centers around the fact that the brain has evolved to work best when we are viewing the world in 3D.  However, almost all optical illusions are presented in 2D; in other words, on paper or on a screen. The brain, expecting 3D is treated to a healthy dose of 2D artwork, and thus becomes prone to assumptive errors.

Not all optical illusions are based on errors. We've become extremely good at inventing them. Some illusions can “tickle” a single, tiny bundle of specialized neurons. Other illusions can be used to demonstrate a single process or characteristic of sight, such as self-visualization of our natural blind spots, or help us to visualize how photochemical receptors work. Optical Illusions are research tools. They can also be more fun than a barrel of monkeys.

There are also plenty of free-range, natural illusions, such as camouflage, mirages, and afterimages. Rock formations or mountains that look like familiar objects, clouds that look like angels and wallpaper-pattern faces are all considered optical illusions. Still more illusions are born in the artist’s studio, such as impossible objects, and ambiguous figures.


Five senses; an incurably abstract intellect; a haphazardly selective memory;
a set of preconceptions and assumptions so numerous that I can never examine
more than minority of them - never become conscious of them all.
How much of total reality can such an apparatus let through?
C. S. Lewis (1898 - 1963)



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