If you aren't thinking thoughts of the character, you aren't 'in character'.

THE CAMERA CAPTURES EVERYTHING! For the actor, that means not just what your character says it especially means what your character is thinking. Sub-text, thoughts, thoughts of the character, what is the character thinking or how ever you know it by. Doesn't matter what you call it. You need to actually do it. Thinking in character is required while you rehearse, audition and during every take while you are filming. Thinking the specific thoughts the character is thinking also allows you to then be able to speak truthfully what your character speaks. Then the camera will picks up both. Gayla Goehl, Acting Elements