Another great illusion - and this time you get to make it! Have a look at the Three Dragons from Grand Illusions - the movie clip is really quite cool! After seeing the clip I actually went and made it straight away (much easier to make than the penguin) but sadly it didn't turn out as nice as the illusion in the video clip. It seems like you need some light behind the dragon for it to work. Though I'll still put it on my desk at work and see if I get any weird looks :)
Must say this time I had no idea why this illusion works, other than the random guess of our brains getting tricked yet again. However there is a short explanation on the website:
If we move around when viewing a solid object, our brain knows how the object we are looking at should behave. However the dragon gives us the wrong clues, because we mis-interpret what its shape is. We assume that the nose of the dragon is pointing out towards us, but in fact the dragon's head is concave.
So I guess since our brain makes up for the head being concave, it also somehow makes the dragon's head follows us!
Another similar illusion (which I presume works on the same principles) is the Einstein Hollow Face Illusion. If you haven't heard of it or seen it click on the link and have a look at the video. In fact, I can't believe I've just found this website, it is chockablock full of great illusions (or should I say Grand Illusions =P).
Update (25/09/2007) I am no longer disappointed with the dragon as I managed to see the illusion few days ago! Started off with my random decision to film the dragon and since that turned out so well, decided to give it another go. Here are some tips to help see the illusion if you still can't seem to see it:
Stand about an arm's length away from the dragon
Close one eye (this really helps a lot!)
Place the dragon so you're looking at it roughly eye level
Position it so you can see the ears clearly (so not front on, but on a slight angle)
Convince yourself that the snout is pointing out
Once you've convinced yourself the snout is pointing out you should be able to move your head around and the dragon's head should follow :) If you're still finding it hard to see the illusion, take a step back and try again. It is quite hard to see the illusion with both eyes, but I find if you take a few steps back and not concentrate too much on it you might get a glimpse of the illusion.
The first time seeing the illusion in real life is the hardest, but once you've seen it, it is much easier to see it again (but just as amazing). A cool thing you can try when you're seeing the illusion is to touch the snout - now that you can't do with a film.