I have a Bachelors of Art in Psychology and therefore I like to look at art from this point of view. Psychology does a lot of study in perception. It is interesting to look at pieces and wonder if the artist is purposely playing with perception or if it was all accidental. My favorite examples of psychology in art are the ones where the artist has purposefully tried make us see something else. Many of these images make us see something impossible. Check out this slideshow of psychology in Art!!
Some of these images are used in Art Therapy which is an entirely art and psychology based profession. The perfect blend of both my degrees. I still want to be an art teacher, but this wouldn't be a bad fall back. I found a few examples of book on the subject while looking for pictures. I think I might have to read these!