Earlier quoted context omitted.
There is a way to help yourself. Put the pair of images in front of your eyes. Bring your finger between your face and the image. Now look at your finger. Move your finger back and forth. While doing this, notice that at a particular distance, the images in background will perfectly overlap each other. That's your moment. Pull out your finger and look at that image. --- Should take lot less tries to learn doing it wi…
I tried, this, and I can get it to overlap in the background, but as soon as I take my finger away, I lose it.
Here is what worked for me. I used my laptop, zoomed in a bit on the images and brought the screen fairly close to my face. I ensured that the image was crisp using each eye (I also have astigmatism, and I probably also need reading glasses, but there is a sweet spot where both eyes have good focus, and I ensured I was there.) While crossing my eyes a bit, I start to see a third image in the center of the two images, but it's either out of focus (like two overlapping images), or it's very thin, like it's not the full image. I relax and keep my attention on this imperfect image and try to focus on it without trying too hard. Using this approach the image suddenly comes into focus and I no longer have to try to keep it there.
I feel like the key might be to notice the very beginning of the desired image in the center and then to try and focus on it, but in a bit of a relaxed way.
Incidentally when it works it is extremely weird! The other images essentially disappear and it's like you've travelled to another dimension.