Light switches wired wrongly

[JohnW2]

Concentrate on something distant, such as the clock or light switch, then without breaking that concentration pass a single finger across your vision, it may work better if you try it say 6-12" in front of your face.

That's rather different from what I was talking about but, in any event, it doesn't work for me. In fact, if I am concentrating on the distant object, I can't really tell if there are one or two fingers at 6-12" with re-focussing onto them (in which case I obviously see just one).

Having said that, it wouldn't surprise me if what you said happened, since stereoscopic vision only works with the whatever one in concentrating/focussed on - the brain then combines the two slightly different images from the two eyes to produce a single'3D' one. Something much closer will be out of focus, so the two different images will not get combined properly, so one might well see 'two fingers' if they are much closer than whatever one is focussed on. However, as said, that does not work for me.

In any event, this is not what II described as the way of determining eye dominance. It is a totally standard test and, as I said, one holds a finger at arm's length, in line with some distant object, and then closes each eye in turn. It was in response to that that morqthan a said that he saw two fingers or two distant objects, and I still don't understand that.

 

[JohnW2]

Im playing with this now and I'm shocked it's not blatantly obvious to you, physics make it impossible to not be there.

As I've just written, it's not 'blatently obvious' to me because it doesn't happen for me, regardless of whatever you say about physics. We're not arguing about theory, I'm merely describing how my vision actually behaves!

 

[SUNRAY]

I've tried to simulate what I see.
I set up a pencil 450mm from the PC screen and took 2 photos at 600mm approximately 30mm apart and roughly took the same image of the screen lining up the 2 orange arrows:

When I look at it this is what I see

I'm merely describing how my vision actually behaves!

I get that but I'm really struggling to work out how you don't see the same thing, assuming of course you have reasonally effective eyesight in both eyes.

In any event, this is not what II described as the way of determining eye dominance. It is a totally standard test and, as I said, one holds a finger at arm's length, in line with some distant object, and then closes each eye in turn. It was in response to that that morqthan a said that he saw two fingers or two distant objects, and I still don't understand that.

I also read your suggested test and like Morgthan all I saw was 2 objects and fail to understand what your test is supposed to achieve

 

[morqthana]

It was in response to that that morqthan a said that he saw two fingers or two distant objects

Yes - when I have both eyes open, before I do the alternating closing.

 

[JohnW2]

I've tried to simulate what I see.
I set up a pencil 450mm from the PC screen and took 2 photos at 600mm approximately 30mm apart <2 images>

These two images are what one would expect of those first two photos, essentially showing 'parallax' (i.e. the pencil in different positions relative to screen background)

.and roughly took the same image of the screen lining up the 2 orange arrows: When I look at it this is what I see <image>

I don't really understand this or what it is meant to illustrate - could you perhaps explain a little more. It looks like a simple superimposition of your first two photos.

I get that but I'm really struggling to work out how you don't see the same thing, assuming of course you have reasonally effective eyesight in both eyes.

I'm still not really clear as to what you are seeing. What you've been saying would seem to imply that everything in your field of vision that you're not focussed on is seen 'double' - which obviously can't be the case and would make no sense. My eyesight is fine in both eyes, and very similar in the two eyes.

I also read your suggested test and like Morgthan all I saw was 2 objects and fail to understand what your test is supposed to achieve

It's not 'my test'. It's the standard test of eye dominance that I was first taught over 50 years ago and which remains one of the standard tests today. As for 'what it is supposed to achieve', I thought I had adequately explained and illustrated that way back in post #24 on page 2. However, maybe the more detailed diagram below will help you to understand...

As I explained, when, with both eyes open one concentrates/focusses on an object, one's dominant eye looks directly towards it ('perpendicular' to one's face), whilst the non-dominant one rotates towards the dominant one in order to also look at that object. Hence, if one concentrates/focusses on a distant object and aligns a finger (held at arm's length) with that distant object, the situation is per the left-hand bit of diagram below, and one hence obviously sees the finger and distant object to be aligned (since that iis how one has positioned one's finger!).

If, without moving one's head or finger, one closes one's non-dominant eye, nothing actually changes. The dominant eye is still looking directly forwards at both the finger and distant object, which are therefore still seen as aligned - as in middle bit of diagram.

However, if (again without moving head or finger) one closes one's dominant eye, then the non-dominant one, looking a little 'sideways' towards the dominant side, sees finger and distant objects at different angles, hence being seen as laterally separated, not 'aligned'.

.

 

[morqthana]

OOI, can you make autostereograms work?

 

[JohnW2]

I also read your suggested test and like Morgthan all I saw was 2 objects and fail to understand what your test is supposed to achieve

Having just read the (more explicit) comments I wrote in the diagram I've just created and posted, I wonder if I was perhaps less clear than I should have been in explaining 'the test' ... what one needs to do (with both eyes open) is to focus on the distant object (clock or whatever) and then interpose one's finger, at arm's length, so that it aligns with that distant object.

Things might go wrong if one doesn't focus on the distant object and, in particular, one certainly should not focus on the finger (which is one of the things that morqthana mentioned).

 

[JohnW2]

Yes - when I have both eyes open, before I do the alternating closing.

Thanks for confirming - but, as I've said to Sunray, I can't reproduce that in myself - and that's just an empirical fact, not any sort of theoretical argument

However, I'm still rather confused by what you and he are saying. There''s obviously nothing special about the finger and clock (or whatever) that we've been talking about but, although it's what you both seem to be implying, I'm sure it's not the case for either of you that if you focus on a nearby object, all distant objects appear 'double', or vice versa, so I suspect I still don't really understand what either of you is telling me!

Whatever, what do you experience if, with both eyes open, you focus on something 'distant', interpose a finger at arm's length so that it aligns with that distant object and then alternately close your eyes?

 

[JohnW2]

OOI, can you make autostereograms work?

Sometimes, yes, but by no means always or easily

 

[JohnW2]

Hmm. When I try that, if I focus on the distant object I see two fingers, and if I focus on the finger I see two distant objects.

Yes - when I have both eyes open, before I do the alternating closing.

However, I'm still rather confused by what you and he are saying. There''s obviously nothing special about the finger and clock (or whatever) that we've been talking about but, although it's what you both seem to be implying, I'm sure it's not the case for either of you that if you focus on a nearby object, all distant objects appear 'double', or vice versa, so I suspect I still don't really understand what either of you is telling me!

@morqthana .... having thunk a bit more, I'm still confused about what you (and quite possibly also Sunray) are experiencing...

"before you do the alternating closing", all you will be doing is looking at a semi-distant object (like a clock) with a finger interposed between your eye and that object - and, generalising, the clock and finger could obviously be 'anything'.

Are you really saying that if you focus on one of those two things you see two of the other thing??

The 'other thing' will obviously be out-of-focus but, at least for me, it certainly isn't 'duplicated'.

 

[SUNRAY]

These two images are what one would expect of those first two photos, essentially showing 'parallax' (i.e. the pencil in different positions relative to screen background)

Yes my whole point

I don't really understand this or what it is meant to illustrate - could you perhaps explain a little more. It looks like a simple superimposition of your first two photos.

I'm unable to mix photos but essentially if I were to look at the screen without the pencil I'd see the text with both eyes, adding the pencil obscured the left of my view for the right eye and the right of the view for the left eye, what I haven't been able to show is the text superimposed on the pencil

I'm still not really clear as to what you are seeing. What you've been saying would seem to imply that everything in your field of vision that you're not focussed on is seen 'double' - which obviously can't be the case and would make no sense. My eyesight is fine in both eyes, and very similar in the two eyes.

Anything that is not at the same distance as the focussed image will automatically be double as the brain is unable to tell the difference between the 2 pencils it sees

It's not 'my test'. It's the standard test of eye dominance that I was first taught over 50 years ago and which remains one of the standard tests today. As for 'what it is supposed to achieve', I thought I had adequately explained and illustrated that way back in post #24 on page 2.

Quite frankly no as I'm unable to see what you seem to describe, IE if I hold up a finger it will be in front of the object but the other finger will appear in front of something else

However, maybe the more detailed diagram below will help you to understand...

As I explained, when, with both eyes open one concentrates/focusses on an object, one's dominant eye looks directly towards it ('perpendicular' to one's face), whilst the non-dominant one rotates towards the dominant one in order to also look at that object. Hence, if one concentrates/focusses on a distant object and aligns a finger (held at arm's length) with that distant object, the situation is per the left-hand bit of diagram below, and one hence obviously sees the finger and distant object to be aligned (since that iis how one has positioned one's finger!).

If, without moving one's head or finger, one closes one's non-dominant eye, nothing actually changes. The dominant eye is still looking directly forwards at both the finger and distant object, which are therefore still seen as aligned - as in middle bit of diagram.

However, if (again without moving head or finger) one closes one's dominant eye, then the non-dominant one, looking a little 'sideways' towards the dominant side, sees finger and distant objects at different angles, hence being seen as laterally separated, not 'aligned'.

.View attachment 383941

Okay I'll humour you, I look at the pot of cooking utensils 18ft away then hold up a finger at arms length and position it without refocussing from the utensil pot... result:

Which of the 2 fingers I see should I position in front of the pot?

To put it another way: with one eye I see this

with the other I see this

and both together I see this albeit the text will appear across the 2 pencils

 

[SUNRAY]

@morqthana .... having thunk a bit more, I'm still confused about what you (and quite possibly also Sunray) are experiencing...

"before you do the alternating closing", all you will be doing is looking at a semi-distant object (like a clock) with a finger

2 fingers, one

interposed between your eye and that object

and the other interposed between the eye and something adjacent to the object

- and, generalising, the clock and finger could obviously be 'anything'.

Are you really saying that if you focus on one of those two things you see two of the other thing??

Yes that is EXACTLY what we see

The 'other thing' will obviously be out-of-focus

Yes of course, as shows in my pics of the PC and pencil

but, at least for me, it certainly isn't 'duplicated'.

And I for one don't/can't understand why not

 

[morqthana]

Do you wear glasses, John?

 

[JohnW2]

Are you really saying that if you focus on one of those two things you see two of the other thing??

Yes that is EXACTLY what we see

... so if your eyes are focussed on something at a certain distance, you see anything closer or further away as 'double'? That sounds bizarre!

 

[JohnW2]

Do you wear glasses, John?

Only for very close stuff (less than about 500mm) - reading books/papers, writing, phone & tablet - even a laptop screen is usually far enough away for me not to need glasses.

Everything I've said/reported relates to the situation without glasses.