Method 1 - Face it
1. Put your face close to the screen or printed stereogram. Try to look through the image, pretending it doesn't exist. Of course you won't be able to see anything yet because image is too close to the eyes.
2. Always hold stereogram horizontally, do not turn and do not bend it. Don't tilt your head and try not to blink.
3. Then start to move back from the stereogram (or move stereogram away from you) very slowly. Your eyes naturally will try to refocus back on the image but you will need to force your eyes not to do so. Keep looking through the image and moving back from it slowly at the same time. If it happens that eyes focus on the image start Step 1 again.
4. Once you can keep looking through the stereogram, keep moving it (or your head) back and force very slowly. At some distance, when patterns overlap each other, you will notice that something strange is happening to the image. That's a very good sign and after a while you will see blurry levels of depth or some 3D images.
5. Once you can see blurry 3D picture, keep looking at it this way. Don't force your eyes to focus yet, they will need some time to adjust. After a few seconds or minutes you'll see how image snaps and becomes very sharp. When it happens you will know that you can see the stereogram.
Method 2 - Relax Your Vision
1. Put stereogram in front of you, let's say 30cm(1 foot) and start relaxing your vision. You can remember how you did the same when you were reading book too long and your eyes couldn't concentrate on the text anymore. Try to do that again with a stereogram, relax your eyes until picture becomes blurry and doubled.
2. When you relax your eyes naturally diverge (look apart or to infinity). Using this trick try to relax eys a little or some more. This will make your eyes to diverge on different angles. At some angle you will see that a hidden image appears. When it happens eyes should stick to this angle and you'll be able to see hidden 3D.
3. Once you can see blurry 3D picture, keep looking at it this way until it becomes sharp and recognizable.
Method 3 - Look Through
1. Find some object in your room, for example a picture on the wall, or a toy on your table, could be anything you can look at.
2. Take a stereogram in your hands and start looking on the object you picked.
3. Start moving the stereogram from low to high slowly, until it blocks view to the object, but keep looking at the object all the time. In other words you need to close object with the stereogram, keep looking on the object. If your eyes switch to the object, lower the stereogram and try Step 2 again.
4. Once you can keep looking at the object and the stereogram doesn't distract you, try various distances between you and object. At some distance you will see the hidden image in the stereogram.
5. Once you can see blurry 3D picture, keep looking at it this way until it becomes sharp and recognizeble.
Method 4 - Reflection
1. Put your stereogram behind a glass door or window or laminate it with a glossy plastic. This method will work with CRT monitors as well.
2. Turn on a lamp behind you so that you can see its reflection in the glass.
3. Look at the stereogram which shoul be from the other side of the glass and then look at the lamp and the hidden image should pop up. If it doesn't work try to move lamp closer to you and try again.
Method 5 - Blink Your Eye
1. This method is not very common, but it could work if nothing else worked. Close one eye and look at the stereogram with only one eye opened
2. Try to not to concentrate on the stereogram and relax your vision.
3. After a few seconds open the eye which was closed and 3D image will pop up.
Method 6 - Transparency
1. This method requires a stereogram printed on film or plastic sheet so that it's transfluent and you can look through it. A contour stereogram will work the best.
2. Just look through transfluent stereogram at something with solid color, for instance white wall in your room.
3. Move stereogram slowly and change distance to the wall untill hidden image appears.