Skeptical Psychic Fair in Chicago a Hit & How Ouija Boards Fail

On Friday, July 23rd, the Women Thinking Free Foundation held a skeptical psychic fair in Chicago as a fundraiser while also having some fun exposing the various tricks & techniques that go into all manner of psychic nonsense.

Among all the drinking & merriment, there were a number activities that we had, including a tarot card silent auction, a “psychic showdown”, along with some fun mentalism & magic tricks.  We also handed out many copies of Michael Shermer’s Learn to be Psychic in 10 Easy Lessons! which outlines the tricks of the psychic trade, including such time-honored (and completely NON-paranormal) techniques such as cold reading.

My primary contribution to the event was to bring a Ouija board to demonstrate a lesson in critical thinking regarding these supposed “spirit boards”…

The whole trick behind the standard operation of a Ouija board is a well-documented & understood phenomenon called the ideomotor effect, whereby the people holding their hands on the pointer of the board (the planchette) subconsciously maneuver it around without necessarily knowing it.  In fact, with Ouija boards, tests have been performed that illustrate that when the people using the board are blindfolded, and the board is randomly rotated without their knowledge, then all the supposed messages from the “spirit world” turn into gibberish.  Just take a look at this footage from Penn & Teller’s Bullshit where they tested a Ouija board in just this manner… 🙂

The ideomotor effect also explains why so many people fool themselves into thinking that dowsing works (or, as is more often the case, doesn’t work) various divination devices such as dowsing rods or a crystal pendulum (another demonstration at our event).

My particular twist on the Ouija board demonstrates a very cool aspect of physics.  What I do is use a “special planchette” which is a silvery disc of metal – the participant in the demonstration picks up this disc and waves it back & forth a few millimeters above the board while various eerie invocations are made.  The result: the “spirits” of the board tug & pull on the disc – the more the user pushes & pulls the disc, the more the “spirits” react.  In fact, one can even drop the disc and it will settle down onto the board slowly and gently as opposed to falling freely under the influence of gravity!!!

But here’s the upshot, and where the critical thinking, come in: I then remove the board to reveal a thick slab of copper metal underneath, and I tell the participant to repeat the demonstration.  The results are exactly the same!  Thus, through a simple application of Occam’s Razor, one can easily conclude the obvious: the Ouija board has nothing to do with the observed phenomenon.

So what’s going on?  Well, as I stated earlier, this is a demonstration of well-known physics, specifically two related phenomena called electromagnetic induction & magnetic braking via eddy currents. It all has to do with the interaction between my “special planchette” (actually a powerful neodymium magnet) and the copper beneath it.  Check out this Youtube video of me performing this demonstration (without the Ouija board) along with the written explanation…

On March 16, 2010, I attended a meeting of Physics Northwest (PNW) where I presented one of the demonstrations I use to illustrate electromagnetic induction & magnetic braking. You take a large slab of high-conductivity, oxygen-free copper (mine is 10 inches in diameter & 1 inch thick) and place a very strong neodymium magnet atop it (my magnet is one from http://www.wondermagnet.com). As the magnet moves in the vicinity of the copper conductor, there is a changing magnetic flux through the copper which – in accordance with Faraday’s Law – will induce eddy currents within the copper disk. These eddy currents then interact with the magnetic field of the magnet, producing – through the right(left)-hand-rule – a force which opposes the original motion of the magnet.

For added physics pizzaz, we added in some liquid nitrogen. The LN2 cools down the copper, reducing its electrical resistance and allowing there to be a much larger induced current in the disk. The increased current then leads to much larger magnetic braking forces. This leads to all manner of really awesome effects, many of which seem almost magical if the observer doesn’t understand the underlying physics. Even for someone who *does* understand the physics, it’s still pretty awesome. This is one of the best demos I do all year, and my students are always excited to play with the setup!

By the way, in keeping up with the 21st century, there is now a version of the Ouija board for the iPhone or iPod-Touch – and, just for reference, it works on exactly the same principle as the original: the ideomotor effect, no “spirits” required.