Absolutely loved them as a kid! Had a quite a few books.

You can do them two different ways. The normal way with the objective popping out towards you and an inverted way with crossing your eyes that inverts the shape.

I’m pretty sure I did it the cross eyed way. I’m doo trunk to understand how to do it another way

Bring the page close to your nose, let your eyes kinda naturally loose focus from distance. Then slowly start to pull the page back and you should get it.

Kinda difficult to describe.

Check back when you are sober and see if you get it to work.

Maybe I have it mixed up then because the way I’m doing it is losing focus and letting it adjust until I see something. I thought I was going crosseyed but I didn’t have a mirror so I can’t be sure.

The way this works is that the image is designed to appear ‘beyond’ the surface it is printed on. It’s much easier to relax your eyes and pretend you’re looking at what’s ‘behind’ the paper. Kind of like 3d chalk art on the road in a way.

The other way of crossing your eyes works because you’re swapping the left and right eye, which gives a different, inverted appearance. Instead of a foreground image popping out of the background, it looks like the other way. Like looking in a box, kinda.

I can do both, but the latter is more difficult, sometimes requires a specific distance, and can be painful if you force it. If the image is too big, you may only be able to see a part of it. I think the first method is easier to do and to learn/train. Either way, you aren’t looking at what’s ‘on the surface’.

…

The best way I can explain is: pretend you’re sitting on the toilet, really tired and you have nothing to look at so you just lose focus and gaze at random stuff. When the tiles or cracks start to make pictures that aren’t there, that’s kind of the effect you want.