It's this simple, do they appear to think about the Questions you ask them, or do they simply reply? That being said, your Question is quite open ended, and needs to be more specific on topics, range and form of analytical thought for a more accurate answer. Because as it stands you can say that everyone fits the standard for 'thinking outside of the box.'

It's this simple, do they appear to think about the Questions you ask them, or do they simply reply? That is all.