Hehe! i tried for fun to see if it's possible for the eyes to merge two images into one. So i opened an image in photoshop, made a copy and set both side by side. Then using a cardboard that i placed vertically and perpendicular to the screen, i put one eye on eachside so that each eye can look at one image only, right eye look at right image, left eye look at left image... it work!!! If the 2 images are not too far appart, my eyes could effectively merge the two images into one.
Then i tried the same thing with a youtube video of Oculus rift where you get the two separate images and sure enough i was able to merge the two and i could effectively see in 3D. The only thing though is that i cant do that in full screen, the two images are too far apart but in a regular window it work fine. It's quite low res but at least you get the feeling of the real thing!!!