That needs training, took me quite some time to learn this in the early 90s when the Magic Eye books [1] came out and autostereograms could be found in many newspapers. I personally also never learned to cross my eyes, I instead make them look parallel, see the diagram in [2]. Once you have learned it, it is hard to unlearn, to the point that once in a while my eyes and brain will snap onto repetitive patterns like grid paper or just text without any intention to do so.
>once in a while my eyes and brain will snap onto repetitive patterns like grid paper or just text without any intention to do so.
When autostereograms were all the rage in the late 80's I had a program on my Mac Plus that let me make/edit them and I used to edit for hours WHILE looking at them in 3D. Then one time I was walking down a hallway with a repetitive wallpaper pattern, my eyes did the thing, the entire hallway appeared to shift in front of me, and I stumbled and fell.
> Once you have learned it, it is hard to unlearn, to the point that once in a while my eyes and brain will snap onto repetitive patterns like grid paper or just text without any intention to do so.
Rare that I meet someone else that does this. I learned how to do magic eye puzzles as a young child, I think my first was in a magazine and I ‘solved’ it the standard way of placing it close to your nose then slowly pulling back. Before long I could just do it on command and as an adult I find myself doing it all the time, often unconsciously. Makes spot the difference puzzles trivial, that’s for sure
[1] https://en.wikipedia.org/wiki/Magic_Eye
[2] https://en.wikipedia.org/wiki/Autostereogram