Wired Magazine: Magic & the Brain


The most recent issue of Wired magazine contains a story about Teller's collaboration with neuroscientists Stephen Macknik and Susana Martinez-Conde (previously mentioned here) on the recent Nature Neuroscience Reviews article entitled "Attention and Awareness in Stage Magic." The article also contains a full deconstruction of a Penn & Teller classic, "Looks Simple," wherein a series of normal-looking behaviors involved with lighting and smoking a cigarette are revealed to be anything but normal. It's a perfect demonstration of how so much of our perception is driven by automatic, implicit assumptions:

"House" of Cards

The folks over at iTricks.com posted this fun video of Hugh Laurie and Stephen Fry performing a magic trick during a talk show interview. Hugh knew that House does magic?! Ha!...puns.

On Gestalt "Good Continuation" in Magic

We live in a world with depth, and consequently, we learn at an early age that obscured objects don't disappear...They're just out of our line of sight. They may still be visible for someone who has a different viewing angle. Partially-obscured objects pose a similar problem. Since we've learned about depth through experience, we know that the cow pictured below isn't in two pieces. His body continues behind the post. In fact, beyond simply knowing this, our brain actively fills in what we cannot see.


This filling-in process demonstrates some relatively-lawful consistencies that were first observed by psychologists in the Gestalt movement (famous for their mantra that the whole is greater than the sum of its parts). The most notable principle formulated by the Gestaltists, as far as magicians are concerned, is the Gestalt grouping principle of good continuation. The simplest way to explain good continuation is through the following graphic:


Given an obscured grouping of sticks, not only do we implicitly assume that the sticks continue behind the tree (rather than there being four sticks), but we perceive the sticks to continue in an established direction behind the tree. We effectively fill in the trajectory of the sticks. Removing the tree demonstrates that our implicit assumptions and filled-in perceptions may be flawed, as there is an alternative (although highly improbable) potential grouping, namely two curved sticks.

Magicians love it when an audience makes assumptions, and automatic, implicit assumptions are the best kind of assumptions for magicians to work with. If an audience does not question their filled-in perceptions, it's quite simple for a magician to operate without their covert manipulations being detected. I would argue that the Gestalt principle of good continuation is the most often exploited perceptual tendency in magic. Take the most well-known of all stage illusions, cutting a woman in half. It would not be an effective illusion if audience's didn't fill in the space between the assistant's head poking out of one end of the box and her feet poking out the other. Often times, magicians will facilitate this filling in process by painting a representation of the assistant's body on the outside of the box. In actuality, the woman's body is much like the sticks pictured above. The illusion works because your filled-in perception of the location of her body does not jive with the actual orientation of her body. This is just one of many instances of good continuation in magic. Here's a collage picturing a number of other well known effects that employ similar principles.


Now that you feel you have an intuitive sense of one of the most pervasive methods in magic, I want you to watch this version of the classic sawing a woman in half illusion developed by the Pendragon's and performed here by "The Twins". It just might break your brain.

Update (11/01/2010): I recently published a paper on this topic (entitled "The Exploitation of Gestalt Principles by Magicians") at the journal Perception. You can find more info on the paper on my website at http://www.public.asu.edu/~abarnhar/Magic.html#Gestalt

WPA Blogging/Tweeting

My lab (I say "my" as if I run it) will be traveling to Portland, Oregon this week to attend the annual conference of the Western Psychological Association. It's a conference that isn't exactly cognition-heavy, but three of us will be presenting our research in a session on information processing (see page 62 of the program here). If I attend any interesting talks or see any interesting posters, I'll either blog about them here or tweet about them here.

I'm speaking on motor activity in the hand during lexical access. Sure...it's an obscure topic. The talk might be lame, but I'm certainly proud of my PowerPoint slides. Here's a flavor of what you'll be missing.


If you're really interested in motor activity during reading, you can read a little about my research on my website, here. Any suggestions on what we should do while in Portland? We're definitely going on a Portland Underground Tour.

Update: I've posted video of my presentation on my academic webpage here: http://www.public.asu.edu/~abarnhar/Handwriting.html

Friday Magic Showcase: Tom Mullica

This is the act that made Tom Mullica famous, honed over many years of performing at his own magic bar, "The Tom-foolery." Now, his time is spent performing a wonderful Red Skelton tribute show all over the country. Visit www.tommullica.com for more information.

Phantom Third Limb?!?

After suffering a stroke, a 64-year-old Swiss woman is reporting the presence of a "pale, milky-white and translucent third arm." According to a news article at swissinfo.ch, this is only the ninth known case of a "supernumerary phantom limb."

The upshot is that the woman can use the apparitional extremity to relieve very real itches on the cheek. It cannot penetrate solid objects. She does not always perceive the arm but "retrieves" it when needed, doctors told the Swiss news agency.

Swissinfo.ch: Doctors confirm woman's imaginary third arm

art from http://davidshillinglaw.bigcartel.com

Justin Kredible @ ASU

On Wednesday, April 15th, ASU is hosting a performance by Justin Kredible. I remember Justin from when he was just a wee whipper-snapper. I happened to be just a wee whipper-snapper at the time, myself. He's seen a lot of success in recent years, appearing on a number of TV shows, including multiple appearances on the Rachael Ray Show. Below is a clip from one of Justin's performances at the Magic Castle. He's a talented, entertaining magician. I hope that you'll come out to see him if you live in the area. It's free...you have no excuse not to come. Here's the info:

What: Justin Kredible Show
Where: ASU, Hayden Lawn
When: April 15th, 8:00pm

Science News: "Blinded By Magic"


The cover story of the most recent edition of Science News is a discussion of how neuroscientists (and psychologists) are increasingly turning to magic as a means to understand the processes underlying perception, attention, and even consciousness. Researchers Susana Martinez-Conde and Stephen Macknik from Phoenix's Barrow Neurological Institute (who have penned a number of great review articles on the topic of magic and neuroscience) were interviewed for the article, as was magician and psychologist Gustav Kuhn who was previously cited in my talk, "The Eyes Have It." It's an entertaining read...and open-access to boot!

Science News: Specialis Revelio!

hat tip to Mike Hout

Friday Magic Showcase: Tony Chapek

From The Gwinnett Citizen:

“I started thinking of ways to combine slight of hand with video,” Chapek said of the act. “So I began doing tricks with video and started passing coins through the TV screen.” Chapek was a regular at the Atlanta Magician’s Club, and one day he showed his act to the club. They went wild. Buoyed by his peers support, Chapek sent a demo of his act to the television show America’s Funniest Home Videos. The ABC Network liked the clip so much that it flew Chapek to Hollywood to appear on the show with the host Bob Saget. Chapek was on a roll. In 1991, one year after appearing on national television, Chapek attended the IBM, not the networking giant but the International Brotherhood of Magicians. At the Baltimore event Chapek was one of 25-magicians presenting their act. From that number 6-finalist were picked to showcase their act. Finally, one person was selected as having the best original act. Chapek was the last man standing.

"The Fallacy of Personal Validation"


What do pseudo-psychics and the Myers-Briggs personality inventory have in common? They both take advantage of what Bertram Forer termed "the fallacy of personal validation." That is, when presented with a series of personality traits or characteristics, people tend to overlook the fact that these traits are present in most individuals, and perceive the list to be a high-quality representation of their own personality.

This is the core principle in the practice of "cold reading," the method that psychics use to convince a mark that they are "in tune" with their thoughts or are capable of speaking to their dead relatives. The general strategy is that by rapidly presenting a series of statements, attentional limitations will force the mark to only attend to the elements of the reading that fit with their self perception. Based on feedback from the mark, the psychic can then begin to make more specific guesses in order to personalize the reading.

The Myers-Briggs personality inventory is one of the most prevalent personality tests and has gone through a number of revisions in the course of its development. It was originally designed by Isabel Briggs Myers and her mother as a tool for directing people to the vocation they were best suited for. In 1975, it was taken over by Consulting Psychologists Press, Inc. In its current state, the inventory classifies people into one of 16 possible categories (a combination of levels on four different factors). The resulting personality description sounds much like what you would hear from a psychic (or a horoscope). Here's one description taken from The Skeptic's Dictionary:
Usually have original minds and great drive for their own ideas and purposes. In fields that appeal to them, they have a fine power to organize a job and carry it through with or without help. Skeptical, critical, independent, determined, sometimes stubborn. Must learn to yield less important points in order to win the most important.

As Forer (1949) stated,"The individual lacks the quantitative frame of reference necessary for a critical comparison of the printed description and his own self-reference," thus concluding that the description is a solid representation of his or her personality. Forer tested this tendency by administering a personality test to a group of his introductory psychology students. One week later, he provided them all with what they thought were the resultant personality descriptions. In actuality, each student received an identical personality description with their name at the top of the page, which read as follows:
You have a great need for other people to like and admire you. You have a tendency to be critical of yourself. You have a great deal of unused capacity which you have not turned to your advantage. While you have some personality weaknesses, you are generally able to compensate for them. Your sexual adjustment has presented some problems for you. Disciplined and self-controlled outside, you tend to be worrisome and insecure inside. At times you have serious doubts as to whether you have made the right decision or done the right thing. You prefer a certain amount of change and variety and become dissatisfied when hemmed in by restrictions and limitations. You pride yourself as an independent thinker and do not accept others' statements without satisfactory proof. You have found it unwise to be too frank in revealing yourself to others. At times you are extroverted, affable, sociable, while at other times you are introverted, wary, reserved. Some of your aspirations tend to be pretty unrealistic. Security is one of your major goals in life.

As you can see, this is an exceedingly general description, and most people possess many of these traits (although in differing levels). Forer had his students rate how well the personality description reflected their personalities on a scale from zero to five, with five being "perfect." He found that the students overwhelmingly perceived the description to fit their personalities to a high degree. Only one student gave the description a rating below 4, and the average rating was 4.3. Just as in the case of cold reading, the sheer volume of items in the description forces people to only focus on those items that seem to fit. They completely ignore inaccurate items.

I know what you're saying: "Oh, that could never happen to me. I'm an astute, logical person. I don't understand how those students couldn't see through the charade." Well, just for fun, I posted Forer's personality description on my Facebook page, and asked friends to rate it on how accurately it fit their personalities. Here are the results:

Despite my small n, a large number of my participants rated the description as being quite representative of their personality. The mean was much lower than in Forer's experiment, but remember that these participants did not complete any sort of personality test before receiving their "results." Thus, there was reason to be skeptical. So, next time you are watching a psychic, I hope you'll keep this information in mind. Don't fall into the trap that is the fallacy of personal validation.


Dutton, D. (1988). The cold reading technique. Experientia, 44, 326-332.

Forer, B. R. (1949). The fallacy of personal validation: A classroom study of gullibility. Journal of Abnormal Social Psychology, 44, 118-123.

ASU Origins Symposium

The ASU Origins Symposium began yesterday with a kick-off panel discussion on issues in science journalism. Interesting talks and symposia will be going on at ASU through Monday, featuring some of the biggest names in science (Hawking, Dawkins, Pinker, Ramachandran, the list goes on). Many of the events are not open to the public (and I couldn't score an invite), but they will all be simulcast on Cox Channel 116 and Quest Choice TV Channel 138. In addition, there will be live webcasts of many of the events found here.

I'm particularly interested in the events happening Sunday. The first panel discussion (starting at 9:30 AM) is on consciousness, complex cognition, and language. Be sure to tune in!

Friday Magic Showcase: Meir Yedid

Meir Yedid became famous within the magic community for his "finger fantasies," wherein he makes his fingers disappear one at a time. This may be the most ironic story in all of magic. From www.MeirYedid.com:
In 1986, a car accident severed a third of his right hand, the hand used for the routine. After nine micro-surgeries and a year and a half of extensive therapy, Meir continues to amaze audiences with a refined sense of magical dexterity and buoyant resiliency. He again claimed the S.A.M. Close-Up Magic Championship, in 1988, although this time performing his trademark finger routine with his left hand. This made Meir the first person to win the award more than once. He also received a special originality medal for his creative contributions to the art of magic.

I was lucky enough to be in the audience for the taping of this clip years ago at Tannen's Magic Camp.

Never Cheat a Monkey

And there's truth to it, too! (Hauser, 1992)

via cynical-c.com

Best April Fools Day Prank EVER!

Wow. I am in awe of this prank. This is an easy way to make your friends think they are psychic. The instructions are contained in this video:

The gimmicked video for the prank is located here: http://www.bbc.co.uk/bbcthree/videohub/esptest.shtml

Have fun!

American Psychologist Special Issue: Darwin & Psychology

American Psychologist

The most recent issue of American Psychologist is devoted to papers discussing Darwin's contributions to psychology. In addition to the obvious connection between Darwin and the burgeoning (although often questionable) field of Evolutionary Psychology, the special issue also addresses the influence that Darwin had on the psychological theories of his cousin, Francis Galton. The journal isn't open-access, but you can view the table of contents here. It should make for some enjoyable reading!