Gedo's book is rather apt for the line of thought you seem to be pursuing!

I had particularly liked her insights into the minds of artists like Magritte, Picasso and others ...

What the artist expressed when he did and what was his state of mind and being when he expressed is what she deals with in depth and I also found psychoiconography to be a sensitive yet perceptive method to 'look' at people so to speak!

Also there would be a cultural dimension to 'expression'. If it is OK by you it might help if you say which part of the world you belong to!

Cheers

Me Paparazzi