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When you record a video while pointing the viewfinder towards the screen showing a live preview you create optical feedback: video example. An anoalogous effect occurs when you turn your microphone towards the speaker.

Once you look at your own retina with the same eye, does our brain create a similar effect as recorded in the video? Or could it be something different all together?

Obviously the best way to find out is to 'just go ahead' and see for myself, but it seems as if I don't have the proper conditions to test this at home: The pupil gets too small in the mirror and thus the retina is plain dark. Such an experiment would require eye drops to force widen the pupil and allow for more light onto the retina.

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  • $\begingroup$ Dear mods, I'm not confident if this question is fully appropriate for your site or if it's better to post at cogsci.stackexchange.com. Please decide if you need to migrate this question. $\endgroup$
    – gentmatt
    Feb 6, 2014 at 21:27
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    $\begingroup$ There wouldn't be any feedback loop, because retina is not an "output device". You'll need to wire the eye to the visual cortex or something to have a feedback loop you want. $\endgroup$
    – Memming
    Feb 6, 2014 at 23:21
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    $\begingroup$ @Memming Indeed, thanks! This is what I have been trying to say in my answer as well. $\endgroup$
    – gentmatt
    Feb 6, 2014 at 23:38
  • $\begingroup$ @gentmatt - why do you link to a youtube video which is private/unaccessible ? $\endgroup$
    – Martin Vegter
    May 23, 2016 at 14:45

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There was an answer posted here and deleted again - which I think has found the error my question. Please undelete it :)

What the eye observes once it glances at the retina is a physically constant image of the retina.

In order for the optical feedback loop to work however, the retina image 'in' the mirror would need to be affected by what is projected onto the retina of the observing eye. Since the retina image in the mirror is constant (there is no link of any kind between whe mirrored retina an the observing retina) the projected image onto the retina of the observing eye is constant as well.

The loop is broken and there is no optical feedback.

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    $\begingroup$ I deleted my question just after posting it because I had some doubts and wanted to improve my answer (which I didn't finally :)). But re-reading it, I bet you were right I shouldn't have deleted it. $\endgroup$
    – Remi.b
    Feb 10, 2014 at 1:25
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You would see your retina and that's all. There would have no "mise-en-abyme".

In order to experience this feedback loop you describe, you need to see something which includes the total picture of what you see. For example: You might see a woman holding a frame of the totality of what you see.

enter image description here

When you look at your retina, you can't see something which includes the total picture of what you see, you just see your retina! It would probably work if the retina was a mirror (or any output device)

This question might not really a good fit for Biology.SE. You might have a chance to make a good fit by asking a question on the mechanistic nature of the process called mise-en-abyme on Phylosophy.SE. And ask wether one can live this same process with any of their sense (perception). You can ask whether the Larsen effect (audio feedback) is a similar process to the one we experience when looking at this picture and in what terms they are similar and in what terms they differ. If you ask such question, I welcome you to add the link on this post (except if the post get closed)!

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Feedback means that the output from a device is fed back to it as new input. You can feed input to a retina, but cannot take its output.

You will get no feedback if the microphone is not linked to a speaker, or cannot hear the speaker.

You will get no feedback if the video camera is not pointing to the display.

Your eye consumes input, but this input is only used to change the state of your brain in mysterious ways. No output is produced. There is no "Kodak" organ in the human body which reproduces with fidelity the image seen by the retina*. Without output, there is nothing to feed back - same as how you can't get feedback when a camera is not linked to a display. A display, with human beings, would be analogous to a magic machine that reads your mind.

If you looked at your retina, you'd see your retina. Just like a camera pointed at a mirror would see a camera.

The closest thing you can do is imagine yourself, imagining yourself, imagining yourself... Although you would probably need to take mind-altering substances to experience this fully.

*: I say no organ exists, but it is possible for humans to reproduce an image they've seen. It's called "painting". Some famous painters apparently have included an image of themselves in their picture, depicted while painting the picture.

This isn't really a classical painting, but to give an example:

enter image description here

The trouble is that actually painting a picture takes a long time, so the feedback is very slow - each iteration may take days.

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