Think of all the portions on the top half as heads and all the portions on the bottom half as legs. As you can see in the two pictures, the number of legs is always 14.
On the top picture, there are 15 heads counting the disembodied head in the corners (the bowtie.)
On the bottom picture, there are also 15 heads counting the disembodied head third from the right (the girl in the bikini with no bottom half.)
So what happens between the two pictures? The first disembodied head (the bowtie) is paired with a set of legs, and, though the subsequent swapping of heads and bodies that results, we are left with the disembodied head in the second pic (the extra girl.) Cool illusion.
Think of all the portions on the top half as heads and all the portions on the bottom half as legs. As you can see in the two pictures, the number of legs is always 14.
On the top picture, there are 15 heads counting the disembodied head in the corners (the bowtie.)
On the bottom picture, there are also 15 heads counting the disembodied head third from the right (the girl in the bikini with no bottom half.)
So what happens between the two pictures? The first disembodied head (the bowtie) is paired with a set of legs, and, though the subsequent swapping of heads and bodies that results, we are left with the disembodied head in the second pic (the extra girl.) Cool illusion.