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“Pigeon Neck” Illusion (2014)

michaelbach.de

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Re: “Pigeon Neck” Illusion (2014)

#71

Post by newaccount74 »

Here's my attempt at explaining this phenomenon:

Our Retinas don't send raw data to our brain like a camera sensor would. Instead, the neurons in the retina already do some pre-processing, like boundary detection, or movement detection. The brain then receives signals where movement was detected.

This movement detection is basically just detecting changes in light level, so it works better when the contrast is high (dark gray vs. white) and works less good when contrast is low (dark grey vs black).

So our brain gets stronger "movement" signals when there is high contrast, and it looks like the part that has high contrast is moving faster. Since the image is designed in a way that the boundary of head/body always have low/high contrast or vice versa, it seems they are moving with different speeds.

Re: “Pigeon Neck” Illusion (2014)

#72

Post by jrumbut »

albert_e wrote: post #51

The illusion was very strong on my mobile screen and non-existent on my desktop screen. The screen calibration was different in the latter I believe so the pigeons were appearing as a slightly different colored grey blocks visually distinct from the vertical bars.

Funny, I still get the illusion after turning the pigeons every color from dark grey to bright yellow.

Brighter colors make it a bit less strong but still very much there.

Re: “Pigeon Neck” Illusion (2014)

#73

Post by soxocx »

bmitc wrote: post #46
soxocx wrote: post #19

Earlier quoted context omitted.

Thats interesting. I see it with either or both eyes.

The illusion is much less if I zoom in and even less if I close one eye, so maybe they had their device up close to their face?

You are right. If I tilt the screen while changing distance to the screen and keep blinking with my eyes while I do this, I, besides looking like a maniac, can weaken the effect and even make it disappear entirely.

Re: “Pigeon Neck” Illusion (2014)

#74

Post by Enginerrrd »

jrumbut wrote: post #72
albert_e wrote: post #51

The illusion was very strong on my mobile screen and non-existent on my desktop screen. The screen calibration was different in the latter I believe so the pigeons were appearing as a slightly different colored grey blocks visually distinct from the vertical bars.

Funny, I still get the illusion after turning the pigeons every color from dark grey to bright yellow. Brighter colors make it a bit less strong but still very much there.

On my laptop, I am only able to see the illusion if I looked at the striped background and blur my vision a little. Then it is quite impressive and strong. Otherwise, it always appears perfectly smooth for all colors.

Re: “Pigeon Neck” Illusion (2014)

#75

Post by thfuran »

thomassmith65 wrote: post #54
TheSpiceIsLife wrote: post #41

Earlier quoted context omitted.

How is viewing an image on a screen an illusion? There really is an image there when viewed at the intended scale.

The image is a grid of pixels. When a group of the pixels that the human viewer perceives as a worm appears to grow, we cannot claim that the pixels in the overlap actually belong to the background. It is equally valid to claim they belong to the worm, in which case... the worm actually has lengthened.

Yes, but the illusion occurs when the worm/pigeon and the grid aren't actually the same color.

Re: “Pigeon Neck” Illusion (2014)

#76

Post by mannykannot »

IshKebab wrote: post #64
the_af wrote: post #44

Earlier quoted context omitted.

> Slide it all the way to black For the record: the illusion still works for me if I slide the color all the way to black. One eye, both eyes, it always works for me.

Not really - he's saying when it's fully black there is no illusion. The chicken is really moving like that.

On the other hand, with black-on-black, the idea that there is something representing a moving pigeon is a sort of illusion in itself, as you infer a boundary that you never see in full.

On the third hand, movement is an illusion in all cases: what's really happening is that static pixels are changing color and brightness (the pixels may jitter slightly in changing color, but that's not the motion we perceive.)

All these views seem to me to be reasonable, they are just different perspectives.

Re: “Pigeon Neck” Illusion (2014)

#77

Post by daveslash »

jrumbut wrote: post #72
albert_e wrote: post #51

The illusion was very strong on my mobile screen and non-existent on my desktop screen. The screen calibration was different in the latter I believe so the pigeons were appearing as a slightly different colored grey blocks visually distinct from the vertical bars.

Funny, I still get the illusion after turning the pigeons every color from dark grey to bright yellow. Brighter colors make it a bit less strong but still very much there.

I get the illusion for yellow, but not for bright red or blue. That's interesting....

Re: “Pigeon Neck” Illusion (2014)

#78

Post by thomassmith65 »

thfuran wrote: post #75
thomassmith65 wrote: post #54

Earlier quoted context omitted.

The image is a grid of pixels. When a group of the pixels that the human viewer perceives as a worm appears to grow, we cannot claim that the pixels in the overlap actually belong to the background. It is equally valid to claim they belong to the worm, in which case... the worm actually has lengthened.

Yes, but the illusion occurs when the worm/pigeon and the grid aren't actually the same color.

In the physical version, if the worm/pigeon and the grid are exactly the same color, we still consider them separate entities.

In the digital version, if a group of pixels appears to be part of some object, that's as good a reason as any to argue it is part of that object (though strictly speaking, it's a meaningless question since it's just a bunch of pixels).

Re: “Pigeon Neck” Illusion (2014)

#79

Post by TheSpiceIsLife »

thomassmith65 wrote: post #78
thfuran wrote: post #75

Earlier quoted context omitted.

Yes, but the illusion occurs when the worm/pigeon and the grid aren't actually the same color.

In the physical version, if the worm/pigeon and the grid are exactly the same color, we still consider them separate entities. In the digital version, if a group of pixels appears to be part of some object, that's as good a reason as any to argue it is part of that object (though strictly speaking, it's a meaningless question since it's just a bunch of pixels).

You're talking about two different things.

One is an illusion, or the set of all illusions, and the other is the set of all images generated by pixels.

Not all images generated by pixels are an illusion. Otherwise you would say that all images generated by, say, acrylic paint, are an illusion because they're made of molecules.

Re: “Pigeon Neck” Illusion (2014)

#80

Post by thomassmith65 »

TheSpiceIsLife wrote: post #79
thomassmith65 wrote: post #78

Earlier quoted context omitted.

In the physical version, if the worm/pigeon and the grid are exactly the same color, we still consider them separate entities. In the digital version, if a group of pixels appears to be part of some object, that's as good a reason as any to argue it is part of that object (though strictly speaking, it's a meaningless question since it's just a bunch of pixels).

You're talking about two different things. One is an illusion, or the set of all illusions, and the other is the set of all images generated by pixels. Not all images generated by pixels are an illusion. Otherwise you would say that all images generated by, say, acrylic paint, are an illusion because they're made of molecules.

That we perceive paintings of objects as objects is an illusion, clearly. But that is not the same illusion as this "pigeon neck" thing.

An illusion is not an illusion if what you perceive is what is actually happening.

The whole point of the "pigeon neck" illusion is that it tricks the eye into perceiving areas as growing that we know are incapable of growing. If the areas are inelastic matter, that's a cool effect: we know that a printed image on a transparency sheet cannot truly grow just by sliding it around a table.

If the areas are pixels... it's less significant. Nothing is actually moving to start with. It's all neighboring lights flashing on and off. If a group of those lights is part of an object, it's only to the extent that the viewer perceives it as such.

Note that this is not the case with other digital illusions. This one in particular is ruined because it relies on a strip of pixels 'belonging' to one of the two (perceived) objects that sandwiches it.

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