Is there a hole in your hand?
We answer that later. We have two eyes and both eyes have their one visual representation of objects (images). One eye sees one image and another sees another image but our brain combines both images into one and we think that we are seeing one image (whatever is in front of us).
To really know each eye sees different image, you can trick your eyes and trick your brain too with an eye fooling trick.
Ok, let's get into it. Use a paper tube and look at a distance through it, put another halfway up to the side of it so that it touches its side and look with both eyes.
One eye was looking at a distance object through paper tube and your another hand was right in front of another eye.
Now it appears that you have a hole in your hand. Well, that was quiet easy eye fooling.
Here two images from both eyes are superimposed to make it look like a hole in your hand? Is there really, check your hand, that's enough fooling for today.
This vision is called stereoscopic vision. It is the type of vision in which you see different images separately. Stereoscope is a device which allows you to see different images separately, and further allowing you to view three dimensional images such as one image in xy-plane and another image in xz-plane.
