The Optical Illusions Appreciation Thread

Leaferne

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Doesn't run on Macs. :evil:
 

Mighty_Emperor

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Sun 21 May 2006


Seeing double: brainwaves offer scientists key to unravelling how optical illusions trick the mind

RICHARD GRAY SCIENCE CORRESPONDENT ([email protected])

SURREALIST paintings may never be the same again. Scientists have deciphered the secret behind how the brain can be tricked by optical illusions.

Psychologists at Glasgow University used advanced brain-imaging technology to map the brainwaves of volunteers as they looked at surreal images.

They found that the participants' brains absorbed all the information from a painting by breaking it down into separate "brainwaves", tiny electrical impulses in the brain.

But the researchers claim that while all the brainwaves occur at once, the brain is only able to decode one at a time, meaning the volunteers could only concentrate on a single aspect of the painting.

Dr Phillipe Schynes, who led the project, claims this explains why the brain is so easily fooled by optical illusions featuring hidden images that seem difficult to miss once they are noticed.

Examples include the picture where viewers will either see two faces opposing each other or a vase.

Schynes believes the brain has to switch between these brainwaves in order to "see" another part of the image, explaining why people experience a sudden moment of clarity.

He now hopes to use the research to understand why people can recognise faces. He believes that familiar faces trigger brainwaves that are easier for the brain to decode than unfamiliar ones, giving a feeling of recognition.

"We are really examining how the brain processes information and interprets images," he said. "In ambiguous paintings, people will see two possible interpretations of a painting but they will not see both at once.

"The brainwaves associated with one part of a painting may be slow, while another part may be fast. Although both sets of waves are created at the same time, the brain is only sensitive to one at a time, so it has to switch between them in order to see each, but cannot see both at once."

The study used paintings by artist Salvador Dali, who regularly hid images in his paintings as optical illusions, to examine brain activity.

When volunteers stared at his Slave Market with the Disappearing Bust of Voltaire, they either saw a scene featuring two nuns at the centre or the face of the great 18th-century French philosopher Voltaire.

They never saw both at once.

By breaking the painting down into two components, the researchers were able to measure the frequency of brain activity associated with each part.

They found that while the nuns sparked fast brainwaves, the brain activity produced by the parts of the painting necessary to see Voltaire were far slower.

Brain mapping techniques showed that due to these differences, the brain was only able to cope with one kind of brainwave at a time. Those that saw the nuns had to "switch" to the other kind of brainwaves to see Voltaire.

Schynes, who has helped to set up a neuro-imaging unit at Glasgow University to study the human brain, added: "Each person will use different parts of the same image before they can perceive it. By masking all other parts of the painting we were able to isolate the information that each volunteer needed to see either the nuns or Voltaire.

"We were able to break down that information and work out how the brain responded to those pieces of information."

Professor Dawn Ades, an expert on optical illusions in art at Essex University, said: "This is a very interesting discovery. Dali produced many double images which were brilliant exercises in the mysteries of perception."

This article: http://news.scotsman.com/arts.cfm?id=753622006

Last updated: 20-May-06 00:50 BST
The Slave Market with the Disappearing Bust of Voltaire:

http://artchive.com/artchive/D/dali/dal ... e.jpg.html
 

OneWingedBird

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That was ripped off, somewhat less effectively, for the cover of the Alice Cooper album Dada:

 

rynner2

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Not seen that one before. At first I couldn't see 'Voltaire', but when I did it clicked in very suddenly. (Rather like those illusions that become a 3-D image when you get your eyes at the right distance from the picture, but focussed beyond the picture.)

The Voltaire image reminded me of a print I've commented on before. Seen close to, it is simply a picture of a young woman sitting in front of a mirror. But from a distance the light and dark areas depict a human skull...
 

escargot

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:shock:

Amazing.

*books eyetest*
 

mindalai

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:shock:

Oooooooooooh!
 

Moooksta

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EXSLENT! EXSLENT!

Can someone post how this works?
 

escargot

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Mooks M8, it's science, that's all there is to it. The likes of you and me wouldn't understand. :(
 

Moooksta

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Hold on SCIENCE!!! That's a school subject!

You mean Max tricked me into learning something, the swine!
 

dreamcatcher5

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I'm sure someone else has already posted this somewhere....
 

Mythopoeika

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I'd say that it works like this:

Staring at the weirdly-coloured picture leaves an after-image on the retina, which persists long enough to overlay and blend with the black and white image when it is displayed.

I checked this out with Paintshop Pro - I copied both the black and white image and the weird coloured image to separate layers, and then made the weird-coloured one less opaque. They blended together nicely, making a naturally-coloured picture.
 

dreamcatcher5

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*ahem*

link killed as threads merged - stu
 
A

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I loved studying (sad but true) the visual pathways of the brain and theories as to 'how' we see.Sadly, no one has provided a good answer yet to the binding problem (re: vision). Nice effect with the illusion, though. :D
 

escargot

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I thought the real colours came up when you moused over it. Like one of them buttons that run off when you try to click them. :lol:
 

MaxMolyneux

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Moooksta said:
Hold on SCIENCE!!! That's a school subject!

You mean Max tricked me into learning something, the swine!
Nah I just thought it was cool since I saw it on another forum. :yeay:
 

original_fLeebLe

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BlackRiverFalls said:
This is really awsome, interior decor painted so it acts as optical illusions from certain angles:

http://www.2loop.com/3drooms.html

apparently the work of artist Felice Varini
i do believe someone else posted those before. they look great but in my opinion are just photoshopped pictures. the theory is right, but the pictures don't ring true. things like bits of monitors on a wall stand being painted as well. i think this type of idea would be very easily achieved using an overhead projector to get the image in the right place.
 

original_fLeebLe

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i just looked at the link on that page. it is outdoor versions of the designs. they state that they are not photoshopped yet they look even more obviously photoshopped than the indoors ones. after all, owners of castle type buildings really want blue circles painted on the historic walls, and town centres also love to have lines painted all over them.
 

OneWingedBird

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i got the links from a discussion of it on snopes. they do look very obviously photoshopped, but by all accounts, aren't...
 

original_fLeebLe

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hereis the thread on snopes, and here is the page which makes them decide it is genuine. interesting.
 

OneWingedBird

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It doesn't say a lot (at least in the babelfish translation), though the pictures do appear to show some of the work being done...

...i wonder if they are photoshopped, but to enhance what's already there rather than to essentially hoax it... there doesn't look to be anything theoretically impossible about the pictures, so much as some of the colours/definition seems too clear to be quite right...
 
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