# Love Those Optical Illusions!



## SINC (Feb 16, 2001)

I've always loved optical illusions. Here's a recent one I received and I hope many of you can post more. Looking forward to seeing "whathaveyou".










1. Follow the movement of the rotating pink dot with your eyes. You will see only one color - Pink.
2. Now stare at the black "+" in the center, and the moving dot turns to green. 
3. Now keep staring at the "+", and after a short time, all the pink dots disappear, and all you see is a rotating green dot!


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## Dr.G. (Aug 4, 2001)

That is a really good OI, Sinc. I am trying to figure out why this takes place.


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## MacDoc (Nov 3, 2001)

Going from memory but has to do with the "fatigue" of your visual cells, persistence of vision and also how specific components of the eye react- the eye has micro movements that keep things visible otherwise either the brain forgets or the cones stop responding to the input.

It's one reason you want to be moving slightly slower or faster than traffic as your brain eliminates stuff that is not moving in relation to you. There are some neat experiments online for this. I'll try and find a few.

They are indeed fascinating and scary in some respects.

good one here

Motion Induced Blindness

lots more

Optical Illusions and Visual Phenomena


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## MACSPECTRUM (Oct 31, 2002)

Dr.G. said:


> That is a really good OI, Sinc. I am trying to figure out why this takes place.


please share if you find out why


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## mr.steevo (Jul 22, 2005)

Hi,

I like this dragon illusion, so much so that I printed off the template and handed them out as Xmas gifts (I'm cheap). Watch the movie to see it in action.

Grand Illusions - Optical Illusions - Dragon Illusion

s.


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## MacDoc (Nov 3, 2001)

I doubt there is a short answer to that Michael as I suspect the OP one involves several of the mechanisms for vision and how the brain interprets.










Apart from the green and white background, how many colours can you see?


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## madgunde (Mar 10, 2006)

mr.steevo said:


> Hi,
> 
> I like this dragon illusion, so much so that I printed off the template and handed them out as Xmas gifts (I'm cheap). Watch the movie to see it in action.
> 
> ...


Thanks for that mr.steevo! I'd seen this before in the Not Pr0n internet riddle.


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## MacDoc (Nov 3, 2001)

Oh this is hilarious but you have to download and play the video to see it work from here..

Grand Illusions Ltd Best Sellers

the Youtuber version is not so clear.

YouTube - Einstein's Face Illusion










remarkable. :clap:


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## SINC (Feb 16, 2001)




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## Guest (Oct 11, 2007)

Dr.G. said:


> That is a really good OI, Sinc. I am trying to figure out why this takes place.


Retention in your eyes -- the afterimages that stay with you for a short time -- and incidentily the reason why interlaced TV signal looks like a solid image for us mere humans (some other animals may see it differently -- to them it looks like the jumble of half images that it is). Add the "negative" efffect. The colors used in that example are negatives, so once you have enough of an image burned in they cancel themselves out.

There was also a test I did online a while ago that really astonished me .. it showed how many blind spots your eyes really have, and what your brain does to fool you into thinking they are not there. I don't have the URL but I'm sure it's easy enough to find via google if you're interested. It really made me shake my head. Our brains do a lot of artistic interpretation of things .. very scary!


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## miguelsanchez (Feb 1, 2005)

For those of you that like this stuff, there is a really good book called Mind Hacks that explains how your brain interprets these images.

It covers more than just OI's though, and offers insight into all of our senses and how the brain interprets the information that it receives.


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## MacDoc (Nov 3, 2001)

There was a really good long article in SciAm last month about how the brain operates - even apparently simple things like explaining the mechanism behind how an alarm clock wakes you is cause for controversy as the brain/neural net is so complex.

It's written in part as a dialogue between two people top in their field who share some views and are have differing views on other aspects.
Fascinating.

Article is

*How does Consciousness Happen.*

How Does Consciousness Happen -- [ DEBATE ]: Scientific American

Given the complexity and diversity it's a wonder we agree on anything we perceive at ALL!!


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## SINC (Feb 16, 2001)

Are you looking into the cylinder from the left, or the right?


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## guytoronto (Jun 25, 2005)

SINC said:


> Are you looking into the cylinder from the left, or the right?


Neither. I'm looking at a bunch of circles.


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## contoursvt (May 1, 2005)

Here is my favorite illusion - might not be work safe 
http://www.killsometime.com/pictures/images/OpticalIllusion.jpg


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## MaxPower (Jan 30, 2003)

contoursvt said:


> Here is my favorite illusion - might not be work safe
> http://www.killsometime.com/pictures/images/OpticalIllusion.jpg


I didn't see the boat.


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## SINC (Feb 16, 2001)

Can you find the lowest step on these stairs?


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## Macfury (Feb 3, 2006)

mr.steevo said:


> Hi,
> 
> I like this dragon illusion, so much so that I printed off the template and handed them out as Xmas gifts (I'm cheap).



Mr. Steevo: I tried to build that little dragon figure, but it didn't work remotely like the video they took of it. How did your experiment succeed in comparison to the video?


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## krs (Mar 18, 2005)

Never saw the tird part of the first illusion.
Even though the moving dot turned green, the stationary pink dots never disappeared.

As to the "Einstein" one - it's a three-dimensional mask, I have seen the same effect with plain tw-dimensional posters although I think there only the eyes follow you as you walk past.


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## MasterBlaster (Jan 12, 2003)

.


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## SINC (Feb 16, 2001)

Here is one similar to the first I posted:










Stare at the centre symbol and a yellow dot appears while blinking. If you don't blink, the blue dots disappear entirely.


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## MasterBlaster (Jan 12, 2003)

.


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## SINC (Feb 16, 2001)

Do you see this window from the top, the bottom, or both?


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## MacDoc (Nov 3, 2001)

and the 2010 winner is 

'Impossible motion' trick wins Illusion Contest - physics-math - 11 May 2010 - New Scientist

just awsome


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## Dr.G. (Aug 4, 2001)

Cool. Luckily, they rotated the ramps to show how it was done.


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## Rps (May 2, 2009)

Not that is a great trick. What is amazing is the thought process to develop it ... which may, indeed, be the trick itself.


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## SINC (Feb 16, 2001)

Yep a neat one that's now destined for mybirdie.ca. Thanks!


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## screature (May 14, 2007)

That is really really cool, like Rps said it is amazing the thought process that went into it.


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## krs (Mar 18, 2005)

SINC said:


> Here is one similar to the first I posted:
> 
> 
> 
> ...


How long does one have to stare at the centre symbol for this to happen?
I have been starin and staring, no blinking, for minutes and all that happems is that the blue dots disappear in one section of the circle, about a quarter, the disappear in a second section but then the dots in the first section come back.
They never all disappear at the same time and I know I didn't blink.
I assume that's all related how an individual brain works in this situation.


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## MacDoc (Nov 3, 2001)

Some boys have all the fun...










Second Best Optical Illusion EVER? | Mighty Optical Illusions


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## Macfury (Feb 3, 2006)

Images like the one above, although cleverly constructed, never struck me as optical illusions, just pictures with other images inside them. For it to be an optical illusion, I think all of the major elements--including the eyes- need to be seen as both a tiger AND something else.


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## MacDoc (Nov 3, 2001)

These say you are incorrect










and dozens more

Julian Beever’s New 3D Sidewalk Paintings | Mighty Optical Illusions


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## Macfury (Feb 3, 2006)

In the one above, I have the choice of seeing the lettering as both flat or as three dimensional, so that one fits the bill.


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## SINC (Feb 16, 2001)

So, this one gives pause for thought. Four perfectly round circles if you trace them with your cursor, but entwined when you look at them. How's that work?


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## krs (Mar 18, 2005)

SINC said:


> So, this one gives pause for thought. Four perfectly round circles if you trace them with your cursor, but entwined when you look at them. How's that work?


The circles don't look entwined to me but only the two inner ones look perfectly round, the outer ones look distorted.
PS: The further you move away from the screen, the less the effect. When I move away far enough, all the circles do look like round circles

I don't see the "entwined" probably for the same reason the lines in this square below all look perfectly parallel to me whereas they are supposed to look wavy.

All depends how your brain interprets the messages sent by the optic nerve (I assume)


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## Dr.G. (Aug 4, 2001)

SINC said:


> So, this one gives pause for thought. Four perfectly round circles if you trace them with your cursor, but entwined when you look at them. How's that work?


Cool. Glad you mentioned the cursor test to prove they are not intertwined.


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## SINC (Feb 16, 2001)

Here's another:


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## krs (Mar 18, 2005)

This begs the question of what actually qualifies as an "optical illusion"
To me, many images posted in this thread don't including the one in the previous post - that's just a three-dimensional image on a flat surface - same as any photograph or image on the screen.


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## Macfury (Feb 3, 2006)

krs said:


> This begs the question of what actually qualifies as an "optical illusion"
> To me, many images posted in this thread don't including the one in the previous post - that's just a three-dimensional image on a flat surface - same as any photograph or image on the screen.


Again, it's all about perception. To me the images above sometimes appear to be rolling. Others don't perform as advertised. 

Perhaps not a true story, but I once heard that anthropologists had shown some optical illusions to members of a tribe who depicted images solely in two dimensions. They apparently had no trouble redrawing even the most effective optical illusions because they saw them merely as lines and shading.


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## SINC (Feb 16, 2001)

If you stare only at one of the dots in the vertical row eighth from the left (or right) the rolling stops and the image becomes still. The "illusion" is the appearance of movement while there is none when viewed normally.


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## SINC (Feb 16, 2001)

So, what about this one?

http://www.youtube.com/watch?v=E9I-Onwfqpo


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## krs (Mar 18, 2005)

SINC said:


> If you stare only at one of the dots in the vertical row eighth from the left (or right) the rolling stops and the image becomes still. The "illusion" is the appearance of movement while there is none when viewed normally.


That's where I have a problem - nothing is moving for me at all.
All I see is a three-dimensional still picture.


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## krs (Mar 18, 2005)

SINC said:


> So, what about this one?


That one is really neat!

Interesting - first time around, after they showed you how the effect was done, I blinked and the floating cube effect was back for the rest of the video clip.

But the second and third time, I did get the effect when I replayed the video but once they showed you how it was done, the effect didn't come back even with blinking or closing my eyes for a second or two.
But the effect is there everytime I play the video clip again.


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