Are these images of faces or vases?

Some images are so complex few people can see more than one subject or may disagree about the subject.

(Click on the image for an example.)

How much reality is shared and how much is purely personal?

Is observation influenced by cultural bias? By training? By scientific training?

What is a scientific fact? Do you believe something because you see it? Or do you see something because you believe it is there?

Do facts depend on interpretation or does interpretation depend on facts? If you believe facts depend on interpretation, are there any facts that do not depend on interpretation? (Read this question again substituting the word theory for interpretation.)