This is not a trick.

Below you will see an actual photograph. They say photos never lie, so all you have to do is figure out what is the subject of this photograph. In it's original form, this is a great "illusion". I hope it reproduces over the web for you well.

The interesting thing about this "illusion" is that once you know what it is, you can't help but see it. In fact, you could come back to this years from now, take one look, and instantly see the subject. What this demonstrates, is that our perceptions can be trained, or influenced by past experiences. You do in many ways learn how to see. You're probably familiar with the concept of stroke victims having to learn new skills, well vision is a skill that is learned just like everything else.

If you can not tell what the picture is, click on picture for a BRIEF look. All you will need is the briefest view of the outline to find out what it is. About 20 to 25% of people do not need help to see it, so don't feel bad if you're in the majority who do need help.