View these images with eyes relaxed, like you were looking at the horizon. It's the same technique one uses for looking at those "3D" prints with all the dots. Putting a piece of paper or cardboard between one's eyes perpendicular to the boundary between the two images may help. Moving closer or further away from the screen can be experimented with. I'm near-sighted, and I do best with my contacts/glasses off and looking relatively close up to the screen. Try what works best for you.

Because image pairs show up with slightly different physical size on different computer screens, it is possible that this method may be very difficult on some screens. Ease also varies from person to person. Personally, I find this my perferred method because my eye muscles are in a relaxed state.

 These images are "backwards" with the left eye's image on the right and the right eye's image on the left. If one then crosses one's eyes the "right amount" the left eye will see the left eye's image (on the right) and vice versa. Trick is to "adjust" the amount one's eyes are crossed so that the images seem to overlap, and at that point they "click" together and becomes 3D! To reduce strain, especially when first starting, it can be helpful to sit back away from the screen so that the amount of cross-eye'ing is reduced.

This method isn't subject to variations in image size like the "straight" image method on the left. Because of this, the image sizes on this site are sometimes much larger (higher resolution) for cross-eyed viewing. Don't do this method long if it's causing eye strain!