The Top Ten Finalists competing in the 2015 Best Illusion of the Year Contest will be announced very soon! In the meantime, whet your appetite with the neuroscience and perception principles behind the Top Ten Finalist and Winning Illusions from last year!

    2014 First Prize

The Dynamic Ebbinghaus

By Christopher Blair, Gideon Caplovitz, and Ryan Mruczek

University of Nevada, Reno, USA

The classical Ebbinghaus illusion, named after its discoverer, the German psychologist Hermann Ebbinghaus, shows that a circle surrounded by smaller circles looks bigger than the same circle surrounded by larger circles. Size is relative to the visual system. The 2014 First Prize winner, an illusion by Christopher Blair and his colleagues from University of Nevada Reno, took the traditional Ebbinghaus illusion and put it on steroids by making it into a dynamic display where the surrounding circles expanded and shrank while the central circle’s size stayed constant. The discovery of the illusion originated with a serendipitous observation by co-creator Ryan Mruczek. While watching movies with his children using Apple’s QuickTime program, Mruczek noticed that the control bar appeared to change in size when going full screen mode – although, in reality, the size of the control bar had not changed. The authors explained that the dynamic Ebbinghaus illusion is at least twice as strong as the original, static Ebbinghaus effect.

Even better, Blair rhymed his 5-minute presentation, Dr. Seuss-style:

There is an illusion, known as Ebbinghaus or Titchener.
Surround circles with circles, and you get the picture.

Surround one with large ones, and it starts to look small,
And another with small ones looks biggest of all.

The illusion is dandy, but it lacks certain flair.
So we here in C-Lab put motion in there.

Didn’t know the result, but we had expectations.
The process has not been without its vexations.

A single arrangement, surround grows and shrinks.
Lacked the effect you’d initially think.

The fact is, we noticed, much to our surprise,
Our illusion’s effect was about half the size.

But if you look to the edge, instead of the middle,
You’ll get an effect, that isn’t so little.

Yet we’d like to go further, we’re sure there’s a way.
So what if our middle, would go and not stay?

As the whole thing traverses, a diagonal path.
The effect it produces, is worthy of gasp.

When we add in the motion of circles and eyes,
Our final illusion more than doubles in size!

Not only this, but it fills us with glee.
The strength of illusion viewed peripherally.

And I can see looks, some are incredulous,
But no ounce of cheating is found within us.

For we can assure you, in all honesty,
That it’s only illusory growth that you see.

The outside is changing; they’re traversing a plane,
But apart from all this, the center’s the same.

If you still don’t believe us, we’ll make it more clear,
By putting some parallel lines up in here.

So as you can see, as they rest on the sides,
The middle stays stable, doesn’t shrink, won’t get wide.

As with any illusion, there’s more we can add,
Though it may not be substance, it’s also not bad.

We may not need colors, as Shapiro would do,
And yet, it can’t hurt, if we use just a few.

Or maybe a grating, peripheral drift,
Is all that we need, to give Ebby a lift.

Perhaps some more motion is needed to win.
I guess we can try it, and give it some spin.

While we may be amused, as we sit in this hall,
What can we say that we learn from it all?

The classic illusions aren’t out of their prime,
Just give them a twist, and they’ll have some more time.

So unlike a dog, who won’t bring back the stick,
Old illusions are something, we can teach a new trick.

    2014 Second Prize

Flexible colors

By Mark Vergeer, Stuart Anstis, and Rob van Lier

University of Leuven, UC San Diego, Radboud University Nijmegen, The Netherlands

Paintings by Picasso and other artists prove that coloring within the lines is not a strict requirement for our visual system’s ability to assign color to shape. Our brain ascribes the colors to the relevant shapes, even if the shapes are depicted minimally with sparsely drawn lines. The illusion by Vergeer and colleagues relies on the same principle, to show that a single colored image can lead to diametrically different color impressions. The left and right colored images on top are identical, constructed by combining the color profiles of a picture of a forest and a picture of the Manhattan skyline. When semitransparent grayscale forest and skyline images are overlaid on the color images, our visual neurons seamlessly match the appropriate colors to the relevant outlines, ignoring the dissonant colors.

    2014 Third Prize

A Turn in the Road

By Kimberley Orsten and James Pomerantz

Rice University, USA

Orsten and Pomerantz used the principles underlying the Leaning Tower illusion to show that two pictures that are physically different can look identical (called metamers). And conversely, that two pictures that are physically the same, can look different (anti-metamers). Of the three images below, which one is the odd man out? Hint: Not the one you think first. Orsten and Pomerantz explain that the human visual system usually does a good job when interpreting true 3D objects, but runs into problems when interpreting flat images such as drawings.

    2014 Top Ten Finalist

Age is an Illusion: it’s all in your Head

By Victoria Skye

Magician, photographer, and illusion creator Victoria Skye was having a hard time taking a picture of a photo portrait of her father as a teen. The strong overhead lighting was ruining the shot, so she tilted the camera to avoid the glare. As she did, she saw her father morph from teen to boy and then to adult. Skye’s illusion is an example of anamorphic perspective. As she tilted her camera back and forth to take her father’s photo, she created two opposite vanishing points, producing the illusion of age progression and regression. In the case of age progression, the top of the head narrows and the bottom half of the face expands, creating a stronger chin and a more mature look. In the case of age regression, the opposite happens: the forehead expands and the chin narrows, producing a childlike appearance.
Skye thinks that her illusion may explain why, when we look at ourselves in the mirror, we see our parents sometimes but not others. “[I] wonder if that is what happens to me when I look in the mirror and see my mom. Do I see her because I tilt my head and age myself just as I did with the camera and my dad?,” she says.

See Victoria Skye tilting the picture of her father below:

    2014 Top Ten Finalist

Pac-Man’s Infinite Maze

By Sebastian Math?t and Theo Danes
CNRS, Aix-Marseille Universit?, France
This Pac-man inspired video game is a demonstration of change blindness, the phenomenon where people fail to notice striking changes happening right in front of them, for lack of attention. You can enjoy the game just as if you were playing Pac-man, with one key difference. What looks at first sight like a regular Pac-man maze is in fact randomly re-generated with every move! The image is always centered on Pac-man, and the maze scrolls across the display as Pac-man moves, so even though the maze is constantly changing, most people take a long time to realize that is the case. If the maze becomes static, as with a regular game of Pac-man, the changes are easily noticeable.

You can download the game here.

    2014 Top Ten Finalist

Pulsating Heart

By Gianni Sarcone, Courtney Smith, and Marie-Jo Waever

Archimedes LaboratoryTM Project, Italy

This Op-art inspired illusion produces the sensation of expanding motion from a completely stationary stimulus. Static repetitive patterns with just the right contrast mix can trick the visual system’s motion-sensitive neurons into signaling movement in the world. Here, the parallel arrangement of opposing needle-shaped black and white lines makes us perceive an ever-expanding heart. Any other outline delimited in similar fashion would also appear to pulsate and swell.

    2014 Top Ten Finalist

Rotating McThatcher illusion

By James Dias and Lawrence Rosenblum

University of California, Riverside, USA

In the classic McGurk effect, hearing the sound “ba” while viewing a face articulating “va” usually results in the observer perceiving the sound “va.” Another classic illusion, the Margaret Thatcher effect, shows that our visual systems are wired to see faces right-side-up, and thus fail to notice grotesque oddities when viewing faces upside-down. Last year, Dias and Rosenblum combined the McGurk and Thatcher effects into a single illusion that shows that our unconscious ability to read lips depends on face orientation. As the face rotates and becomes “Thatcherized”, “ba” remains “ba”: auditory perception becomes less susceptible to influence by the visual (i.e. facial) context.

    2014 Top Ten Finalist

The Disappearing Faces Illusion

By Stuart Anstis

University of California, San Diego, USA

Our visual neurons adapt – respond less vigorously – to unchanging stimuli. Adaptation to contrast in an image is known to act specifically on the edges or contours of objects. Based on this principle, Stuart Anstis reasoned that adapting to a particular photograph should render the visual system less sensitive to that particular image, but not to similar non-adapted photos. In the illusion below, two identical superimposed low-contrast photos of Albert Einstein and Marilyn Monroe are followed by adaptation to a flickering high-contrast Einstein on the left and Monroe on the right. Once the flicker stops, the two identical images no longer look the same, but they reveal Monroe on the left and Einstein on the right. Anstis says that serendipity plays a big role on how he discovers (“stumbles across”) new illusions. “If you walk enough you will stumble over things, so keep walking,” he says. “Pasteur said that chance favors the prepared mind. I find that chance also favors the unprepared mind [emphasis added].”

    2014 Top Ten Finalist

Pigeon-Neck Illusion

By Jun Ono, Akiyasu Tomoeda, and Kokichi Sugihara

Meiji University, JST, CREST, Japan

Our visual neurons can be easily confused about the direction of motion. The illusion by Jun Ono and his colleagues shows that a rectangle progressing at constant speed in front of a vertical grid of stripes appears to shift backwards and forwards instead. The motion is similar to the action of the neck of a walking pigeon.

    2014 Top Ten Finalist

Hybrid motion and the integration of motion elements

By Arthur Shapiro and Oliver Flynn

American University, USA

Another ambiguous motion effect, Shapiro and Flynn’s illusion consists of an array of rectangles that change from yellow-to-blue-to-yellow… over time. The physical position of the rectangles never changes, but they appear to move in opposite directions (left vs right) depending on whether the observer is close to the monitor or far from it. You can also seat close to the monitor and squint or un-squint your eyes to get the same effects. Shapiro and Flynn explain that the illusion results from the conflict between motion processing mechanisms in the brain that are sensitive to coarse-scale versus fine-scale information in an image.