Here are two simple ones I got hold of today. It would be shame to pass them, despite their easy explanation and visual simplicity. When you look at the first one, you immediately think of letter E. But why is that? None of the lines presented depict letter E even closely! Our brain immediately presumes this is something known to us, and tries to connect the shadowy outlines with the known symbol. What if we were born in a society where this symbol wasn’t used, and is nowhere to be seen at all? Could we then see the lines without making presumption of what they represent? Can you force yourself just to see some random lines instead of E? Try it! For the other one, it depends how you look at it – you can either see remains of an apple, or two faces looking at each other? So which one is it?