This is Your Brain on Card Tricks

Posted on February 18th, 2011

by Eric Walton
It is no secret that magic is an art-form based largely upon secrets – secret moves, secret apparatus, secret intentions. If the presentation of magic is to be successful, the magician must know something that the spectator does not and he must keep that something a secret for as long as he can.

But a secret isn't the same as a lie.

A lie is the deliberate misrepresentation of the truth, perpetrated in order to gain some advantage, generally a malicious one. A lie is always told with the intent to deceive, whereas a secret is merely the concealment of the truth or some aspect of it and may or may not involve the will to mislead. I may have a secret tattoo of Genghis Khan on the sole of my foot, but you are unlikely to consider yourself deceived if I fail to disclose the fact when we first meet.
Maybe I have a tattoo of Genghis Kahn on the sole of my foot and maybe I do not. Is it such a big deal either way? Not really.

And while we magicians must sometimes resort to overt lying in order to present our tricks successfully, most of the deception on which we rely is not in the form of lies that we tell our audiences, but in the fabrications and confabulations that take place within the minds of the spectators themselves. By carefully manipulating the sensory data available to his audience, the magician orchestrates a series of “experiential voids” which the spectator (consciously and unconsciously) fills with his own expectations, assumptions and interpretations. Thus, the spectator is not so much the victim of the magician's deception, as he is both a witting and unwitting accomplice in it.

The unconcious act of filling in experiential voids and sensory blanks to create a full experience of the world is known as “schema-driven” or “top-down” processing and is the brain's attempt to create a comprehensive picture of the world around it, often based on very little sensory information. A commonly cited example is that of seeing a cat behind a picket fence. Though much of the cat's body is obscured by the fence, the brain doesn't assume that those parts of the animal are simply missing. It fills in the blanks based on its many previous experiences with cats and fences and constructs a picture of an entire animal and not a Dali-esque version of one.

What every good magician understands is that the act of perception is also an act of imagination; and that the information he gives to his spectators – visual, auditory and otherwise – is fraught with associations and expectations that have formed over the course of a lifetime of experience and will almost always be interpreted in a way that is consistent with that experience.

Specifically, the magician understands that within the spectator's mind (as in his own) a causal relationship between events has been established; and given or denied the appropriate stimuli, the spectator will automatically and unconsciously impose that causal relationship upon everything he sees and hears.

He will quite naturally expect that if he knocks a butter-knife off the table, it will inevitably fall to the floor. His experience of the world has imprinted on his mind the inescapable link between falling off the table and landing on the floor. And if, a fraction of a second after the knife falls, what he hears is not the familiar sound of metal hitting the ground, but the sound of a startled dog, he will not (if he is sane) assume that the knife has magically transformed into a dog, but rather that it landed on the hapless animal who happened to be in the wrong place at the wrong time.
I include this photograph of a phrenology model because no article about the brain, perception and magic would be complete without one.
Our brains (with some unfortunate exceptions) have not evolved to expect extraordinary explanations when ordinary ones will do. It is the task of the competent conjuror to eliminate the ordinary explanations until only the extraordinary explanation remains. And this we do not by fooling the senses, but by inducing the imaginations of our audiences to fill the sensory gaps left by our carefully choreographed actions.

Thus, it is both inaccurate and misleading to say that the magician has fooled your eyes. In order to fool your eyes, I would have to alter the way photons of light fall on your retinas, a feat of which I am hardly capable. A much more interesting and satisfying and exciting task is to compel the imagination of the spectator to fill in the blanks I have left in a way that is consistent with my intentions and my narrative and to induce him to complete a familiar story from which certain passages have been deliberately omitted.

As Shakespeare wrote in (an early, unpublished draft of) Julius Caesar, “The fault, dear Brutus, lies not in our visual cortices, but in our reliance on top-down processing.”

This post was originally published on February 16th, 2011 as "The Role of Imagination in Magic" on the Lincoln Center Institute's Imagination Now blog. I've made some minor revisions to that draft because it's my blog and I can do pretty much whatever I want.

Further reading:

Proust Was a Neuroscientist
Imagination First: Unlocking The Power of Possibility
The Brain That Changes Itself
The Oxford Companion to The MInd

© 2011 Text and phrenology photo by Eric Walton. Photo of Genghis Kahn from here.

Posted in Eric Walton, Genghis Kahn, Magic and perception, Top-down processing, Schema-driven processing    Tagged with Eric Walton, magic and perception, Genghis Kahn, top-down processing


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