American psychologist Joseph Jastrow published the optical illusion on the right in 1899. He used it to express how unconscious preferences help create a constructed reality. It's either a rabbit or a duck, depending on your point of view. The image on the left is going around the Internet today, and appears to be a sculpture inspired by Jastrow's illusion.
Link via Geekosystem
Like the mystery of the chicken and the egg, we finally have an answer! It is, in fact, a rabbit with a beak sticking out of its head! We will never be fooled again!
if you have ever seen a rabbit or a duck you will notice that it looks like neither a rabbit nor a duck. it especially could not be a duck, the "beak" looks ridiculous.
i don't think this illusion has ever demonstrated any psychological effect other than that badly drawn images are hard to understand.
:(