The Optical Illusions Appreciation Thread

Eponastill

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Well it seems there's a 'Best Illusion of theYear' contest. Loads more here:
http://illusionoftheyear.com/cat/top-10-finalists/2019/
What an amazing website, thank you.
But I have to say - between 'Change the colour' and 'The rotating circles illusion' - well anything anyone ever reports that they've seen, weirdness of any description - surely those two illustrate that we can't call anything we report 'objective'. Those are really crazy.
 
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EnolaGaia

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Going 'cross-eyed' is a more reliable way of seeing the 'hidden image' for me.
I see the transition quite clearly by simply moving my head closer to / farther from the display screen.
 

Yithian

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I see the transition quite clearly by simply moving my head closer to / farther from the display screen.
As a thumbnail it appears to be a normal photo of a woman.
 

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I stared at it for a minute and it was still there. How long are you supposed to look at it?
Until your retinas burn out, I reckon.
It didn't disappear for me (and I'm going blind).
 

Yithian

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I stared at it for a minute and it was still there. How long are you supposed to look at it?
It works for me.

First the pinks and blues fade out, and then the yellows expand to take their place before fading out themselves as you lose focus.
 

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If this might be the most appropriate thread...?

A Newly Discovered Illusion Could Help Explain Our Visual Consciousness

Source: sciencealert.com
Date: 18 December, 2020

How much are you conscious of right now? Are you conscious of just the words in the centre of your visual field or all the words surrounding it?

We tend to assume that our visual consciousness gives us a rich and detailed picture of the entire scene in front of us. The truth is very different, as our discovery of a visual illusion, published in Psychological Science, shows.

To illustrate how limited the information in our visual field is, get a deck of playing cards. Pick a spot on the wall in front of you and stare at it. Then take a card at random. Without looking at its front, hold it far out to your left with a straight arm, until it's on the very edge of your visual field. Keep staring at the point on the wall and flip the card round so it's facing you.

Try to guess its colour. You will probably find it extremely difficult. Now slowly move the card closer to the centre of your vision, while keeping your arm straight. Pay close attention to the point at which you can identify its colour.

It's amazing how central the card needs to be before you're able to do this, let alone identify its suit or value. What this little experiment shows is how undetailed (and often inaccurate) our conscious vision is, especially outside the centre of our visual field.

[...]

https://www.sciencealert.com/this-n...n-could-help-explain-our-visual-consciousness
 

gordonrutter

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If this might be the most appropriate thread...?

A Newly Discovered Illusion Could Help Explain Our Visual Consciousness

Source: sciencealert.com
Date: 18 December, 2020

How much are you conscious of right now? Are you conscious of just the words in the centre of your visual field or all the words surrounding it?

We tend to assume that our visual consciousness gives us a rich and detailed picture of the entire scene in front of us. The truth is very different, as our discovery of a visual illusion, published in Psychological Science, shows.

To illustrate how limited the information in our visual field is, get a deck of playing cards. Pick a spot on the wall in front of you and stare at it. Then take a card at random. Without looking at its front, hold it far out to your left with a straight arm, until it's on the very edge of your visual field. Keep staring at the point on the wall and flip the card round so it's facing you.

Try to guess its colour. You will probably find it extremely difficult. Now slowly move the card closer to the centre of your vision, while keeping your arm straight. Pay close attention to the point at which you can identify its colour.

It's amazing how central the card needs to be before you're able to do this, let alone identify its suit or value. What this little experiment shows is how undetailed (and often inaccurate) our conscious vision is, especially outside the centre of our visual field.

[...]

https://www.sciencealert.com/this-n...n-could-help-explain-our-visual-consciousness
Purely in terms of colour your peripheral vision is not so good for that. Your eye has two types of cells, rods and cones, rods see in black and white and cones in colour. The cones are concentrated in your fovea which is basically the centre of your vision. Therefore things seen at the periphery are in black and white and any colour there is your brain trying to put a colour in place. It’s not until your cones detect the object that you will actually see the colour.
 

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This Brain-Bending 3D Staircase Just Won Best Illusion of The Year For 2020

Source: sciencealert.com
Date: 24 December, 2020

It's been one heck of a year, but we're on the home stretch. Now, let's celebrate by looking at something very strange that seems to make no sense whatsoever to my poor befuddled brain.

What we have here is the winner of this year's Best Illusion of the Year Contest for 2020, and it is indeed a worthy mind-boggler, taking one of the best-known traditional 2D optical illusions and realising it perplexingly in three-dimensional space.

Designed by the mischievous mathematician Kokichi Sugihara – a celebrated Japanese illusionist and repeat winner whose work we've featured more than once on the site – this is called the 3D Schröder Staircase.

The classic Schröder Staircase, published in 1858 by the German scientist Heinrich G. F. Schröder, would later evolve into other forms in the work of Dutch artist M. C. Escher, but the striking simplicity of the original is still a stunner.

In the illustration, what at first appears to be an unambiguous depiction of a single staircase seen from above turns out to be two staircases (the other seen from below).

[...]

https://www.sciencealert.com/brain-bending-3d-staircase-wins-best-illusion-of-the-year-for-2020
 

EnolaGaia

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Do you have 'curvature blindness'?

This Trippy Optical Illusion Can Reveal if You Have 'Curvature Blindness'

This optical illusion, discovered by experimental psychologist Kohske Takahashi from Japan's Chukyo University in 2017, is called the 'curvature blindness illusion', and it's just another example of how we can't always trust our eyes when we're looking right at something.

If you're like most people, you'll probably see both wavy lines and zigzag lines in alternating pairs – at least, you will if you're staring at the lines in front of the grey background that dominates the middle of the picture ...

Curvature-Blindness-Illusion.jpg

But now, take a look at the lines in the top-left and bottom-right areas of the image, where the backdrop is either white or black. Notice anything different going on?

If the lines in those black/white areas look wavy to you but you're also seeing zigzag lines in the grey middle section, congratulations: you've just been diagnosed with curvature blindness! (Don't worry, it's not an actual medical condition or anything.)

But why do so many of us see zigzag lines in the picture, when in actuality every line in the image is wavy?

According to Takahashi, it could be to do with how our eyes differentiate curves and corners in the real world – and it's possible the way we tell the two apart triggers some kind of conflict in the brain's visual system. ...

FULL STORY: https://www.sciencealert.com/this-trippy-optical-illusion-can-reveal-if-you-have-curvature-blindness
 

EnolaGaia

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Here's a visual illusion / conundrum that seems to be all the rage on Twitter ...

LateralInhibitionIllusion.jpg
How Many Colors in This Image? Here's The Science Behind The Illusion Dividing Twitter

Earlier this month, a classic optical illusion was posted on Twitter with the question "How many colors do you see?" The poster saw three.

Others replied with numbers as high as 17. And tens of thousands of comments followed in heated debate on what the 'true' figure must be. ...

While it's hard to say for sure, the phenomenon at work is most probably due to an effect first described around a century and half ago by the Austrian physicist Ernst Mach, the same scientist who lent his name to the unit comparing an object's speed with the speed of sound. ...

In 1865 he took interest in an illusion similar to the one we're all marvelling at now – similar colors of slightly contrasting shades becoming easily distinguishable when they touch, but harder to tell apart when separated.

Mach's understanding was that something weird was going on inside the eyeball, specifically within the photosensitive tissue making up the retina. Later these shaded stripes would become known as Mach Bands in his honour.

Remarkably, his speculations were pretty bang-on. Research using better technology than Mach ever hoped to have access to has since confirmed the mechanics behind this weird trick-of-the-eye as a retinal behavior called lateral inhibition. ...
FULL STORY: https://www.sciencealert.com/twitte...-shaded-illusion-here-s-how-we-think-it-works
 

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Sometimes 11 and sometimes 16. Depends on light and how tired I am.
 

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Curiously enough, I don't think this is a Superior Mirage. There is no distortion near the bottom of the boat, which is what I would expect with a mirage. The photographer, David Morris, seems to have a better idea of what caused this- it is a 'false horizon', the result of different colours in the sea itself.
David's son, also David, "we were amazed and very baffled" but that they had in fact seen the phenomenon before.
His picture shows the large vessel appearing to float in the blue sky above the water.
Due to the similar colouring of the sea and sky, the large vessel appears to be sitting amongst the clouds.
It is likely the remarkable optical illusion was caused by a cloud formation closer to the shore, which changed the colour of the water closer to the land.
The boat, being further away, was in a cloudless area and therefore the sky reflected the sea - making it look like the boat was floating.
_117387798_apex_hovering_ship_illusion_03.jpg
 
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