Monday, January 31, 2005

Four-Stroke Apparent Motion

The below clip gives us the illusion of continuous motion. In fact there are only four frames that loop continuously. Two of the frames move forward the other two move backwards.

Copyright George Mather, 2003

George Mather, the creator of this piece, had this to say about this illusion.
This animation involves a repeating cycle of four different frames (hence "four-stroke"). The motorcycle moves forward and then backward again (the scenery moves backward and then forward again), but the backward step is accompanied by a reversal in contrast:

The effect of contrast reversal is to reverse the direction of perceived motion, so instead of appearing to move backwards between frames 2 and 3, and between frames 4 and 1, the motorcycle still appears to move forward. Consequently, the impression is of continuous forward motion. This kind of display was first described by Anstis & Rogers (1986), and is closely related to 'quadrature motion' displays (Carney & Shadlen, 1993).
Go to his site for a more in dept analysis of this and other illusions.
READ MORE - Four-Stroke Apparent Motion

Thursday, January 27, 2005

Vanishing Illusion

This is a fascinating optical illusion. When I first looked at it I thought it was like Herman's Grid and the yellow dots were appearing. As I observed further I realized the yellow dots were actually seeming to disappear. As I focused on an area the yellow dots in adjacent areas disappeared.

The yellow dots placed off the center of sight appear to vanish. "Asagao" is a plant with flowers.
Copyright A.Kitaoka 2003
READ MORE - Vanishing Illusion

A True Optical Illusion

The below is an amazing illusion that is made possible by a blending of art and science. This illusion comes to you from the University of Texas Health Science Center at San Antonio. The way they were able to give this young lady the illusion of having both eyes is incredible.

Life can change in the blink of an eye. It did for Lorie Navejar. But thanks to science, no one can tell. Navejar and her family planned what was supposed to be a fun outing last April. They spent the day in Sadler, Texas and ended up taking a ride on an all-terrain vehicle (ATV). But the off-road adventure took a turn for the worse.

Navejar was riding on the back of an ATV when the vehicle hit a muddy incline and flipped over, landing on top of Navejar and the driver. The handlebar went straight into Navejar's eye . "It went directly into my right eye and went back out," Navejar said. "I covered my eye and stood up praying, ‘God help me. God please help me.’ I have never experienced pain like that and I would never wish it on anyone."

Emergency teams airlifted Lorie to a Dallas hospital. There, doctors sutured the globe of her eye. "At the time, I didn’t think I was going to lose my vision. The pain was actually too bad to think about anything," Navejar said.

...."I felt disfigured, not myself. I didn’t feel presentable to people. I didn’t want to go to a lot of places, I just wanted to stay home," Navejar said, after injuring her eye. "Dr. Sponsel suggested I see Nancy. He said the prosthesis might help the way I felt about myself."

.....Creating Navejar’s prosthesis was a balance between fine art and modern science. Navejar posed as the artists’ model while Hansen and Guerra carefully studied her natural eye, noting the color of every fleck.

Read the entire article.
Absolutely Amazing!
READ MORE - A True Optical Illusion

Wednesday, January 26, 2005

Circles in Motion

I have seen this before but it never triggered as a great illusion. That is until I found it on a site that explained its activation. This is a great anomalous motion optical illusion.

Stare at the center dot and move your head toward the illusion, now pull back. The circles appear to move in one direction on the way in and reverse their motion when you pull back.
READ MORE - Circles in Motion

Tuesday, January 25, 2005

Cyber Illusions

Optical Illusions have been around forever, but with the arrival and spread of the internet we have been able to share a wider array of illusions.

There is one set of illusions that are unique to this media and would be difficult or impossible to replicate without computers and the internet. I refer to these as cyber illusions.

They are self explanatory and you should all beware not to succumb to this illusion or your reality might suffer.

READ MORE - Cyber Illusions

Monday, January 24, 2005

Table Illusion

I had seen this illusion before but for some reason never really focused on it before. Today I saw it on Coach Burke's site and actually read the info. This exposure caused me to search out some additional info and create this post.

This is Roger Shepard’s “Turning the Tables” illusion. Look at the two tables below. If I told you they had an equal surface area on their table tops, you'd probably say "maybe". But what if I told you that they also were identical in both length and width. Don't believe me? Measure them for yourself. This optical illusion appeared in the Jan. 2003 issue of Discover Magazine.

The below image is given so you can print it out, make a cutout of a tabletop, and reposition it over the other one.

Click on picture to go to another solution page for this illusion.

Update: I found this interactive java applet on the Rice University site hosted in their psychology department's space. The applet allows you to really examine this illusion.
READ MORE - Table Illusion

Friday, January 21, 2005

Verbal Illusions

Below are 4 annoying questions, at least I consider them annoying because I fell into every trap! These are from an E-mail message that's making the rounds, so you may have seen them before.

Answer the questions instantly. You can't take your time. It's fun.

No pencil or paper! OK? Ready? ... GO!!!

FIRST QUESTION: You are participating in a race. You overtake the second person. What position are you in?


To answer the second question, don't take as much time as you took for the first question. (You know you took too much time.)

If you overtake the last person, then you are...?


THIRD QUESTION: Very tricky math! Note This must be done in your head only. Do NOT use paper and pencil or a calculator. Try it.

Take 1000 and add 40 to it.

Now add another 1000.

Now add 30.

Add another 1000.

Now add 20.

Now add another 1000.

Now add 10.

What is the total?


LAST QUESTION: Mary's father has five daughters Nana, Nene, Nini, Nono. What is the name of the fifth daughter?

READ MORE - Verbal Illusions

Thursday, January 20, 2005

The Fountain of Mystery

The Fountain of Mystery!I mention in my description of this blog "Blogging All Illusions: optical, magical, visual, science, jokes, funny pictures etc..." Here is an illusion made possible because of science. I thought gravity was a constant and that water couldn't flow uphill. I guess I was wrong.
A set of four glass ramps positioned in a square clearly show water traveling up each of them before it pours off the top, only to start again at the bottom of the next ramp.

It is a sight which defies logic, and has become probably the most memorable image of this year's show. (...)

It is a trick which has greatly intrigued the crowds at the Chelsea Flower Show, where Dyson's work is part of the Daily Telegraph's Silver Gilt award-winning garden. People have been queuing up 10-deep to see the fountain, says Mr Phillips, many of them discussing their various ideas as to how it works.

"I stand a discreet distance away and listen to some of their theories - there are some fantastic ideas there, some of them I actually wish I could make.

The Wrong Garden, Chelsea Flower Show, 2003
Check out this site for a flash presentation of the garden and fountain in action.

Is this a trick as the article says? No, this is not a trick, "trick" sounds like something you would find a magician doing at a 8 year olds birthday party. This mix of art and science is a very convincing illusion. People don't line up 10 deep for something that looks like a trick. The BBC article has an excellent explanation (with pictures) of how James Dyson (of Dyson Vacuum Fame) makes water go up hill. If you must have the mystery revealed click here, but be warned for each person who looks a little bit of the magic left in this world dies.

READ MORE - The Fountain of Mystery

Wednesday, January 19, 2005

Avenue of Illusion

At first glance this is a nice photo of the avenue leading to the Institut de Cultura in Barcelona, Spain. But this particular morning the landscape has changed. The normally quiet street is packed with about 7000 people.

Click on the picture to read one person's account of participating in this photo shoot.

That's right before you is an avenue paved with 7000 nude bodies (all volunteers). The artist for this installation is Spencer Tunick. He has been documenting the live nude figure in public, with photography and video, since 1992. Check out the artist's site.
READ MORE - Avenue of Illusion

Monday, January 17, 2005

Illusion of Danger

I have seen this image around the net for awhile now. I thought that I would post it here because everywhere I saw this image posted people assumed it was this big shark and they all wondered if this photo had been altered in any way. The truth is this picture is real and has not been doctored in any way. After all it comes from a site that specializes in surf action pictures.

The illusion of danger comes from our minds. We see this and automatically think shark, but the reality is that this is a dolphin. Click on the picture to go to They have a second shot where the tail of the dolphin is easier to see and identify.
READ MORE - Illusion of Danger

Bridge Optical Illusion

In 2002 Professor Lastra of the University of North Carolina was invited to speak at SIBGRAPI, the Brazilian graphics conference, in Fortaleza. While there he photographed this bridge which lead to the Cultural Center. At first glance this seemed like an extremely long foot bridge. He was kind enough to allow me to use these two pictures he took.

Anselmo Lastra
Copyright October 2002
Used w/permission

On his web page he stated "Interesting illusion that also works when you're actually there."

Anselmo Lastra
Copyright October 2002
Used w/permission

READ MORE - Bridge Optical Illusion

Hidden in Plain Sight

This is the ultimate "Where's Waldo" type picture (2.5 Gigapixel Image). You can zoom in and count the bricks on some streets. What is the license plate of that car? How many people can you find? Can you find the large McDonalds sign mounted high on a pole for the travelers on the highway to see? Can anyone tell me what time it is? I saw a clock on a tower in the distance with the time clearly visible.

Click on image to go to full 2.5 gigapixel image viewer
Macromedia Flash required to view.

TNO has produced the largest digital panoramic photo in the world. So, what do we mean by large? After all, modern consumer cameras can easily take a picture with 5 million pixels. Well, we are talking about a photo of completely different dimensions. One with 2.5 billion pixels - that's 500 times more pixels. If this photo were printed, it would measure 6.67 m by 2.67 m (300 dpi). The photograph shows Delft and its surroundings in the autumn of 2004. It was taken from the top of the Electrical Engineering faculty of Delft University, at a height of about 100 m, by TNO.
READ MORE - Hidden in Plain Sight

The Lady's Silhouette

Below is a silhouette of a lady. The question I have is which direction is she facing? Is she facing toward you or away from you? When we don't have all of the visual details our mind often fills in what is not there.

Antonio Zamora
copyright 2004
used w/permission

Did your mind fill in the details for her to be facing you or for her to be facing away from you? The truth is from the silhouette above it is impossible to tell, either answer could be accurate. See the below two penciled in silhouettes to see why.

Antonio Zamora
copyright 2004
used w/permission

READ MORE - The Lady's Silhouette

Team Spirit Illusion

Below is what I refer to as the team spirit illusion.

Elis outsmart Harvard.

Click on picture to purchase this poster
The "Harvard Pep Squad" ran up and down the aisles of Harvard Stadium at The Game Nov. 20. They had megaphones in hand and their faces were painted as they encouraged the crowd to hold up the 1,800 red and white pieces of construction paper they had handed out. It would read "Go Harvard," they said.

But the 20 "Pep Squad" members were actually Yale students. And when the Harvard students, faculty and alumni held up their pieces of paper -- over and over again -- they spelled out "We Suck" in giant block letters the whole stadium could read. Read the rest here.
They made a mini movie of their exploit check it out @
READ MORE - Team Spirit Illusion

13th Man Optical Illusion

Here we have an animated gif file. If you look closely you can count 12 little people. After the gif slides the image around you end up with 13 little people. How does this happen? I saw the same optical illusion done once with solid colored rectangles, the rectangle one is easy to see what happens, but this one is much more difficult because it is people.

If your brain starts to seize up and you must have an answer then click on the picture and it will take you to where they devote a lot of words and images to making this possible to understand.
READ MORE - 13th Man Optical Illusion

Sunday, January 16, 2005

Horse or Frog

At first glance this apparent color pencil drawing is a nice picture of a horse. But turn this picture on its side and you have a nice artist's rendering of a frog in a pond. These type of optical illusions are common but they always make a person do a double take.

Horse in a stall


Frog in a Pond

READ MORE - Horse or Frog

Saturday, January 15, 2005

Lego PC Case

Check out this very trippy computer case. Yes this case is constructed entirely of Legos. This was just too cool to pass up. This is his third case of five displayed on his page. Click on this picture to go to his site.

He talks a little about the process here:
To answer some people that seemed to think that I could make money out of this (ha!) I decided to try and come up with a system to be able to access the innards to change out or upgrade parts. Designing and building the door literally took almost an entire week or 2 hours or so each day. I would build it up, and then at some point, it would shatter as it had zero structural rigidity at all.

The initial design was to have the lit fan in the middle of the door, with spokes radiating out to the outside frame, and then plexiglass in between the spokes. The first piece I cut survived, but after that, I decided to use a pattern of legos and give up. The door just would not stay together using the spoke idea. Possibly if I used glue I could get away with it, but half the fun was taking things back apart and improving the idea. It was also looking at this case that I realized (after I disassembled it) that I could build "down" as well as building "up".
READ MORE - Lego PC Case

Tuesday, January 11, 2005

7 Dolphins

This painting is by Jim Warren. It is an illusion of a different type. One the most enjoyable paper activities I did as a kid was the hidden picture puzzles. Find the seven dolphins in this picture and relive a little part of your childhood.

Click on the picture to find the answers on the artist's site.
While your there take a look around it is well worth the visit.

He has another site that you all might be interested in titled "The Great Illusion" written & designed by Victor Kahn with paintings by Jim Warren

The intro reads:
"You have been invited here to experience another reality.
The reality of thoughts, words and surreal images
that are hidden from you ...within your own mind."
READ MORE - 7 Dolphins

Sunday, January 9, 2005

Impossibly Linked Ambiguous Rings

Dr. Donald E. Simanek is responsible for the creation of these two illusions. From his site the following info gives us limited insight into who he is.
Title: Professor of Physics at Lock Haven University of Pennsylvania, Lock Haven, PA, 17745. (1964-1998)

Highest degree: Ph.D. in physics from The Pennsylvania State University (1983).

Interests: Optics, history of science, the science/pseudoscience interface, 3d photography, teaching critical thinking; physics laboratory instruction and physics demonstrations, skepticism; visual illusions, Meccano and Erector designs.

Ambiguous Ring, © Donald E. Simanek, 1996

Below Dr. Simanek modified his Ambiguous Ring above into a truly interesting illusion. This is a more complicated piece that allows the mind to get stuck in unraveling it.

Impossibly linked ambiguous rings. © 2004 by Donald Simanek.

This being a new creation he and his readers are still puzzling over the naming of this illusion. Read his comments about this new creation from his site below.
Finally [Dec, 2004], this illusion evolves into something more interesting. Here two ambiguous rings are ambiguously linked. All of these illustrations are available in higher-resolution versions on request. Readers have suggested several names or captions for it: "the interconnectedness of everything," "a new atomic theory," "tying mental knots," "super-colliding synchronous orbitals," "illusory quantum entanglement," (I like that one.) and "virtual unreality."
READ MORE - Impossibly Linked Ambiguous Rings

Saturday, January 8, 2005

ESP Experiment

Cliff Pickover, I believe is the first to demonstrate this illusion. on his site he states the following:
I am conducting a fascinating ESP experiment. Recent statistics suggest that my system can predict the correct outcome of your choice with 98% accuracy.
This is not one of those cheesy number game tricks. It is so convincing that The Daily Mirror of the UK said the following:
"It's got to be one of the weirdest sites we've ever come across but it's definitely worth visiting. Pop into and you'll be baffled for days - even months. We don't know how he does it but Cliff Pickover, the site's creator, claims he's conducting an ESP test. Click on one of three eyes, he asks, and then look at six playing cards. Without moving your cursor, pick a card, shout out its name and then click on one of six more eyes. It then tells you which card you chose. It claims to be correct 98 per cent of the time but won't tell you how. Every one of the 60 times we tried - and we did everything we could to trick them - they got it right. Spooky!" (page 45)
Cliff has a great site, but in this review they claim to have gone through the experiment "60 times" and "we did everything we could to trick them" only for Cliff's site to guess correctly all 60 times. Admittedly this parlor trick is fun but before those at the Mirror start accusing people of being dumb here in the United States (frontpage Nov 4th) they should take a look in their own mirror.

Go to Cliff's site and check out this illusion for yourself, it is definitely worth the visit. If you can't figure out how it is done check the explanations on the site. If you still can't figure it out check the comments below.
READ MORE - ESP Experiment

Color Me Brain Damaged

If your not careful you might hurt your brain on this one. The younger kids will beat the adults on this test every time.

Look at the chart and say the color not the word.

Left-Right Conflict
Your right brain tries to say the color but
Your left brain insists on reading the word.

Update: This is known as the Stroop Effect. Named after John Ridley Stroop born on March 21, 1897. Sandlot Science has a great interactive demo of this effect.
READ MORE - Color Me Brain Damaged

Wednesday, January 5, 2005

How Many Times did the White Team Pass the Ball?

From the Visual Cognition Lab at the University of Illinois comes this exceptional yet simple illusion.

I almost forgot about it. I saw the movie linked below in a management training session. Sixteen Information Technology managers in a room with just one job, watch the movie and count the number of times the team in white passes the basketball, you would think that one of us would have gotten it right.

Click the link at the end of this paragraph and as long as you have java installed a movie will load. It is 7 megs so it may take a minute or two. After you watch it, come on back and let me know how many times the white team passed the ball. Go to the movie now.

Did the white team pass the ball? (Click one of the answers below)

6-9 times?

10-12 times?

13-15 times?

16-18 times?

This has been called the Illusive Reality Experiment on some sites.
READ MORE - How Many Times did the White Team Pass the Ball?

Monday, January 3, 2005

Folded Chess Set

I found these images on "Beyond Escher for Real" here they took Escher like impossible images and recreated them with some 3d modeling software. From their page they say,
Herein again, we show that many of the illusions look impossible yet could be realized. This work below presents some of these three-dimensional models that were designed and built using geometric modeling and computer graphics tools.
The following is the "Folded Chess Set" by Sandro Del-Prete. The top image models the original drawing from the original perspective. In the bottom image they take the model they built and rotate it to expose how it could be constructed.

"Folded Chess Set" by Sandro Del-Prete

Click here to see a movie rotating the model from front to side.
READ MORE - Folded Chess Set
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