Neddy Bate
Valued Senior Member
Yes, just please keep in mind the tips I gave in post #33 which are based on the lighting being outside the shower stall.
Strange Optical Phenomenon (mirror in shower)
- Thread starter Neddy Bate
- Start date
Yes, just please keep in mind the tips I gave in post #33 which are based on the lighting being outside the shower stall.
DaveC426913
Valued Senior Member
Of course.
I mean, there's no doubt that is an optical illusion, right? That's not really in question. It's just a matter of why does your brain think it looks like it does.
Neddy Bate
Valued Senior Member
No, it is not an optical illusion.
I think Dave is onto something…
https://www.vox.com/science-and-hea...llusion-science-humility-reality-polarization
Neddy Bate
Valued Senior Member
Okay, no problem, so you guys both misunderstood the whole thread. I blame myself for not being more clear.
The thread is about wave interference:
https://en.wikipedia.org/wiki/Wave_interference
More specifically, destructive interference. The light waves are literally cancelling each other out, and making the pupil area appear black.
When you see the colors of the rainbow in a soap bubble, do you ask what your brain is doing to cause the illusion? Or do you look to a physics explanation?
The thread is about wave interference:
https://en.wikipedia.org/wiki/Wave_interference
More specifically, destructive interference. The light waves are literally cancelling each other out, and making the pupil area appear black.
When you see the colors of the rainbow in a soap bubble, do you ask what your brain is doing to cause the illusion? Or do you look to a physics explanation?
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DaveC426913
Valued Senior Member
Yeah, I guess. I was definitely under the impression that it was unsolved and that you did not, as yet have an explanation. I feel a little tricked, what with your asking for help finding one.
When did that happen? Did I miss a post? I've thought I was following pretty closely.
Okay. I tried this experiment earlier, Neddy, and only my right pupil appeared as though it was floating in front of the shower stream. It wasn’t an instant thing - I stared for roughly 30 seconds.
It reminded me of a visual illusion though, where if you stare at an image long enough, the image eventually “changes,” and your brain perceives something else.
It reminded me of a visual illusion though, where if you stare at an image long enough, the image eventually “changes,” and your brain perceives something else.
Some examples that seem similar to the shower/eye ''illusion" :
https://www.scotsman.com/lifestyle/...sions-and-mind-boggling-illustrations-3635990
https://www.scotsman.com/lifestyle/...sions-and-mind-boggling-illustrations-3635990
Seattle
Valued Senior Member
Those are always interesting. The explanations always remind us that our brain isn't an accurate sensor. I remember in elementary school when we learned how the brain will reverse colors when you stare at something for too long. After that, anytime you were bored in class while the teacher was talking, it was common to stare at the flag hanging in the corner for 30 seconds and then shift your gaze to a blank area on a white wall.
The colors would reverse and you would see a flag with green stripes and yellow/orange where the blue had been. Or maybe aliens took over my brain but I think it was just an optical illusion.
Neddy Bate
Valued Senior Member
I thought I had been pretty consistent in saying it was not an optical illusion. I have not gone back to read my posts, but as recently as post #25 which was last week, I wrote, "These are real optical phenomena, not optical illusions."
Yeah, I guess. I was definitely under the impression that it was unsolved and that you did not, as yet have an explanation. I feel a little tricked, what with your asking for help finding one.
It is true that I never said anything about wave interference before now. However, earlier in the thread I had said that I thought the light rays were cancelling each other out somehow, like noise cancelling headphones. It only occurred to me recently that it must be destructive wave interference.
Even assuming the effect is caused by destructive wave interference, it still has yet to be explained which light rays are cancelling which. The light rays have to be coherent and out of phase in order to cancel each other out, so the question remains as to how it can be possible under these circumstances. The question remains as to which light rays are doing what, in order to produce out-of-phase versions of themselves. I do not know, and still cannot understand how it can be possible.
Neddy Bate
Valued Senior Member
Thank you for trying to replicate the effect. It sounds like you did manage to do it successfully.
In one shower, where the lighting is above the sink, I can only manage to see it in one eye, like you said. In that shower, it takes me awhile to line up the mirror correctly, so that the lighting is where it needs to be. In that case, it takes awhile of searching for the effect to appear, so I can see that you might think the effect takes awhile to show up.
However, in the other shower, where the lights and mirror are already in the correct locations, the effect shows up instantly and for both eyes. There is absolutely no need to wait until your retinas "get tired" as is the case with the optical illusions you referenced.
DaveC426913
Valued Senior Member
OK, I didn't know what to do with that, so I guess I did nothing. It's possible we're getting caught in semantics of what "illusion" means.
Surely you must acknowledge that that's a bit premature.
The first step has to be to isolate and independently reproduce the effect, before you can conclude that it is a real physical phenomenon.
I mean, how exactly are you able to rule out that is it an optical illusion? You can't know your eyes are imaging a real effect, surely.
I guess the trick is to capture it with a camera.
Hmm. That’s kind of interesting.
For some perspective, my bathroom’s lights are to the left of the shower (if you’re facing the shower stream), high above the mirror/sink area, and there’s track lighting. No lighting, as mentioned, directly above the bathtub/shower. I’m thinking the brighter it is, the easier it is to see the illusion.
You don’t seem to think it’s a visual illusion — what do you think it is?
Neddy Bate
Valued Senior Member
Well, even optical illusions can be explained. Usually it is a mis-judgement made by the brain. For example, in the checker shadow illusion...
https://en.wikipedia.org/wiki/Checker_shadow_illusion
...the brain easily processes that there is a shadow falling across part of the checker board. The brain also easily processes that all of the light checkered squares would have been painted the same lighter shade of gray, and all of the dark checkered squares would have been painted the same darker shade of gray. So the brain corrects for the shadow, and assumes that all of the lighter checkered squares are the same shade. When it is revealed that squares A and B are actually the same shade (in the image itself which includes the shadow), the brain should not be surprised, because it knows everything is darker where the shadow fall, but it had accidentally "corrected out" the shadow.
So if you want to claim the hovering pupil effect is an optical illusion, you would still have to explain it, just as you would if you wanted to claim it is some actual optical effect.
Now, before you start typing your explanation for how it could be an optical illusion, let me show you the important clues we already have that this is not an error in judgement by the brain.
Study the very subtle differences between the following two images:
Both images are identical in all respects except the hand has moved less than an inch sideways. So whatever explanation you might apply to one would have to apply to the other, unless the location of the hand is somehow critical in this illusion. And if it is, then why did I have to paint the pupil black in photoshop? Clearly moving the hand in the image was not enough to make the shower stream appear to turn black where the pupil is located.
Think of one photo as the "control" for the experiment, and draw your conclusions from there. What does this suggest to you? (Keep in mind these images represent something I was actually able to do in the shower, that is, make the pupil either black or not depending on slight movement of the location of the hand.)
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Neddy Bate
Valued Senior Member
Yes, I agree. The brighter lighting arrangement makes the shower stream more visible, which makes it even more obvious to see the black disk which appears to be hovering in front of it, (as you had also said it appears in front of the shower stream).
I don't have an explanation, but I think somehow the light rays are cancelling each other out by an optical effect called destructive wave interference. That usually involves adding two light rays which are identical, with the exception of one being 180 degrees out of phase with the other. I cannot explain exactly how that is achieved in this relatively simple set-up, but I would think that is what is happening, somehow.
DaveC426913
Valued Senior Member
Of course.
But for the purpose of this discussion, are they on or off the table? Because if they're off the table, then there's little point in continuing to analyze your phenomenon
As above, if you're only prepared to examine it with one favoured lens, then this is discussion is going to go much like Magical Realist's threads about UFOs or ghosts, to-wit:
Rather than 'Could it be real or illusory?', he only asks: 'Since it's real, what could be the (exotic) cause?'
Wait. What? You're suggesting that a flat-coloured, 2D, cartoon image in Photoshop should obey the same perceptual laws as an observation in 3D, infinitely-varied real life of a real life subject?
Surely you jest.
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Neddy Bate
Valued Senior Member
Sorry, I did not realize that you would find "little point" in analyzing how it might be that the light rays could actually be cancelling out. I thought it would be very interesting to know how the light rays are managing to be 180 degrees out of phase exactly in the area of the pupils. If that does not interest you, but the optical illusion explanation does, then I would be more than happy to hear a good explanation for the optical illusion.
Well, you are the one now saying that you are only open to one explanation and not the other. So it sounds like you are also guilty of the same thing you are accusing me of doing. But no matter, I am open to both now. You have piqued my interest in what a good explanation for the optical illusion might be.
The fact is that I did not think it was an optical illusion, so I tried to dissuade you from analyzing as if it were one, especially considering that you had not seen it yourself yet. I was trying to help you not waste your energy, because I didn't think it could be an optical illusion, having seen it myself so clearly. But I am certainly open to that possibility now, if you can explain it adequately. So, what is your explanation for this as an optical illusion?
Well, my cartoon images are all you have to work with, since unfortunately you have not been able to replicate the effect for yourself. So, in one of the cartoons in my above post # 55, there is clearly a shower stream in front of one of the the pupils. And in the other cartoon, the shower stream is not visible, because a black disk is there instead. This can alternate back and forth by moving the finger less than one inch back and forth. Please note that even wegs said she saw the black dot appear to be hovering in front of the shower stream. And I am reminding you here that I found a way to make it go back to normal, and then back to hovering black disk, repeatedly.
I have ascertained from that finger-moving experiment that the effect is visible in each eye separately. We can determine this because the right eye can see itself with the black disk, while at the same time seeing the left eye without it. I am telling you this to help you cover all the bases in your optical illusion explanation. Please study both images in post #55, and refer to both of them in your explanation. For example, you can't just say the pupil appears dark because no light is coming from it, because that does not address the shower stream's visibility at all.
So, please explain at your leisure. Thank you in advance.
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DaveC426913
Valued Senior Member
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OK, it sounds like you're open, so I won't beat the point to death.
I can't. At least not yet. Still, there's nothing yet that rules out the first, most obvious explanation.
OK, so let's note a few things:
1. There is no stream. There are individual drops that are falling fast enough that you picture them as a stream (and that, BTW, is a bona fide optical illusion). Your visual retention means that your retinae can't see things as discrete that last less than 1/10th of a second. That's why cinema films and TVs work.
So we know for a fact that at some given window of time (albeit arbitrarily short) you can, in fact, see any point in your pupil's reflection. Your pupil - no part of it - is actually fully hidden throughout the experiment.
(Note: if this experiment is ever tried with a camera, it will probably require a shutter speed of longer than 1/10th second)
2. Light is always additive. Lack of light does not blot out light. Example: In this combo reflection/transmission, the dark parts of the girl's reflection do not obscure the lit parts of the roadway. Only the light elements of each combine to make the final image.
I am not yet sure how this confirms or refutes a given explanation, it's just something to should keep in mind.
I think, simply the point is that the darkness of your pupil can't actually blot out the light of the water droplets; it's not optically possible. it is more likely a trick of the eye.
Sure. Let's revisit the term optical illusion.
When I'm watching TV without my glasses, I cannot see a barn door if it filled the screen. But if I hold my finger in my vision, the image gets significantly sharper - partly because my finger is blocking certain rays that would otherwise contribute to a blurry image.
Would you call that an illusion? I'm referring to it as an illusion because it is happening in my perception, not out there where the light rays are. It is subjective, for my benefit only. That's really all I mean by "illusion". I don't mean it like a mind "trick"; I mean it like it is an artifact of how our perception works.
And you know what? That's the term I'm going to go with moving forward: artifact.
The "black pupil effect" may be an artifact of your perceptual experiment.
(Don't take my example too literally; I'm still not suggesting there's any actual light being interfered with in your experiment.)
I do not have an explanation yet. Further tests are required before an explanation. But - as with ghosts and UFOs - that doesn't mean, in a vacuum of answers, any more exotic theory is ruled in.
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DaveC426913
Valued Senior Member
(And if you think I'm going to Google "black pupils in shower" your cheese has slipped off your cracker.)