Very interesting, thanks! Especially that second link.
Interestingly, I seem to have a little different effect than they did in the second illusion they present. First of all, I find there are three distinct perceptions, the left-right and up-down that they mention plus spinning (fan motion). I actually didn't see the left-right form at all until getting to the page with the larger star, although when I went back I could see it in earlier pages. On the page with rows of red x and green o with alternating color positions between rows, I see the top row as spinning and the other rows as up-down; after looking at it a bit longer than for the other pages to change it changes to all spinning, then can change back to just the top row spinning. Now when I go back to the similar colored dots page I see the same thing, although I didn't the first time.
Also interesting how you can affect what you see in that illusion - not reliably at first, but with increasing accuracy over a few minutes. Or at least affect what most of them do - that top row on some of them still does its own thing sometimes. I wonder if more complex perception changes would be possible with more practice. Very interesting stuff!
Interestingly, I seem to have a little different effect than they did in the second illusion they present. First of all, I find there are three distinct perceptions, the left-right and up-down that they mention plus spinning (fan motion). I actually didn't see the left-right form at all until getting to the page with the larger star, although when I went back I could see it in earlier pages. On the page with rows of red x and green o with alternating color positions between rows, I see the top row as spinning and the other rows as up-down; after looking at it a bit longer than for the other pages to change it changes to all spinning, then can change back to just the top row spinning. Now when I go back to the similar colored dots page I see the same thing, although I didn't the first time.
Also interesting how you can affect what you see in that illusion - not reliably at first, but with increasing accuracy over a few minutes. Or at least affect what most of them do - that top row on some of them still does its own thing sometimes. I wonder if more complex perception changes would be possible with more practice. Very interesting stuff!