So why, when I put an object in front of one eye, and another object in front of the other, do I see the two objects superimposed over each other? Why, when I cross my eyes, do I see two version of the world slightly offset and superimposed over each other?
I just tried that, and I saw no such thing. As careful experiments have also found no such thing, I must conclude that you are mistaken.
If you put your eyes deliberately out of alignment, objects will appear to be doubled. It is not the same as seeing ghostly, transparent images superimposed one over the other, like a doubly exposed photograph. The fact that you are inclined to interpret your experience this way merely shows that you trying to account for the rather confusing nature of the actual experience in terms of the false, but widespread “folk” theory that the eyes function like cameras sending images back to the brain.
If there is one clear lesson to be learned from the past couple of centuries of experimental research in psychology, it is that people’s introspective reports about the detailed nature of their subjective experience provide, at best, extremely unreliable evidence that, must be treated with great caution and, where possible, critically assessed in the light of more objective experimental data (and if it can’t be, it is often wisest to ignore it). Giving accurate, reliable introspective reports about the detailed nature of ones subjective experience is extremely difficult. It is difficult or impossible for people to do so without their description being contaminated by their preconceptions about what the experience ought to be like, and the mechanisms through which they (rightly or wrongly) believe it to have been produced.
Unfortunately, giving inaccurate, unreliable introspective reports of such experiences is extremely easy, and because in most ordinary circumstances (outside the psychological laboratory) no-one is in a position to contradict them (and there is rarely much motive to do so anyway), most people falsely believe that any such reports that they give are very reliable, or even infallible. All the evidence indicates that this is not so.
It is not that people’s subjective experience of vision supports the eye=camera theory. Rather it is that people interpret their inherently hard-to-articulate experiences in terms of that widely known theory (taught in junior high, indeed). Historical evidence shows that before the eye=camera model became established, people did not interpret their visual experiences in this way, but rather according to the quite different theories of vision that prevailed at the time (such as the once very widespread belief that the eyes work by emitting “rays” that reach out to the object seen).
Many educated people today probably think the eye=camera theory is obviously true. History, however, shows that there is nothing obvious about it. A few centuries most educated people thought that a completely different theory of vision was obviously true. (Science shows that neither of these theories are true, although both contain grains of truth). It only seems obvious because we have had it dinned into us at an early age.
I’ve never thought about eyes as being like cameras particularly. At any rate, I’m not just seeing doubled images, where the two images overlap I can see two different objects occupying the same space. Now maybe I’m not really seeing that, but if that is ultimately my subjective experience then how is that invalid? It would seem that if I could point one eye at the other, I would see two images superimposed, it might not technically be how my brain is “processing” the two images, but if that is my subjective experience then that is what I’m seeing. In other words, if it seems like two images are superimposed, then that is a valid answer to “what would I see if I was looking at a different image with each eye”.
I just tested it out and I can see two different objects simultaneously even if each is only visible by one of my eyes.
Powers &8^]
From Sylvie and Bruno:
“What a lovely old ruin it is!” cried a young lady in spectacles, the very embodiment of the March of Mind, looking at Lady Muriel, as the proper recipient of all really original remarks. “And don’t you admire those autumn-tints on the trees? I do, intensely!”
Lady Muriel shot a meaning glance at me; but replied with admirable gravity. “Oh yes indeed, indeed! So true!”
"And isn’t strange, said the young lady, passing with startling suddenness from Sentiment to Science, “that the mere impact of certain coloured rays upon the Retina should give us such exquisite pleasure?”
“You have studied Physiology, then?” a certain young Doctor courteously enquired.
“Oh, yes! Isn’t it a sweet Science?”
Arthur slightly smiled. “It seems a paradox, does it not,” he went on, “that the image formed on the Retina should be inverted?”
“It is puzzling,” she candidly admitted. “Why is it we do not see things upside-down?”
“You have never heard the Theory, then, that the Brain also is inverted?”
“No indeed! What a beautiful fact! But how is it proved?”
“Thus,” replied Arthur, with all the gravity of ten Professors rolled into one. “What we call the vertex of the Brain is really its base: and what we call its base is really its vertex: it is simply a question of nomenclature.”
This last polysyllable settled the matter.
“How truly delightful!” the fair Scientist exclaimed with enthusiasm. “I shall ask our Physiological Lecturer why he never gave us that exquisite Theory!”
“I’d give something to be present when the question is asked!” Arthur whispered to me, as, at a signal from Lady Muriel, we moved on to where the hampers had been collected, and devoted ourselves to the more substantial business of the day.