This is the answer to the previous visual puzzle post (spoiler alert!), go directly there if you want to give it a try on your own (but don't bother looking for the pervert, he's well hidden). Still planning to show how you can make these puzzles (its pretty easy and somewhat fun), and some variations... next I guess : )

To start, the answer, as Bertrand so deftly pointed out, is that everyone is a bit taller in the picture with 12, and a bit shorter in the picture with 13. So one way to look at is no one disappeared, just everyone sacrificed a body part or two. Here is an example of how it works with boxes. For some reason boxes are easier to understand as they don't have bodies and faces. To answer "who disappeared" in the other puzzle comes down to how you measure a person - if all you care about is shoes, then the kissing guy with the cuffs is the one. If it is the eyes, then maybe the meditating guy. I'm guessing the body section people use to identify people with could tell a lot about them. Lets not go there Robin. Ok. This is how it works with boxes, the people in the puzzle work just like this, only they are staggered:

When the bars are shifted right, they become taller, however there are fewer of them

So no one disappears, or maybe better said, nothing disappears. One way of looking at it is a 'whole person' does disappear, just they disappear a bit from each of the 12 tall figures. If you take each of these little sections that get removed (the section from the tall person that the short person doesn't have), you can splice them together. This composite would in fact be the 'person' that disappeared. I always meant to try this, but never did until tonight. To my shock, it ends up being a screaming man with his hands down his pants. And here he is:

Father Green (Pere Vert) hanging on for dear life