How does a person's thoughts affect his/her use of language?
The question is a bit vague, but I think I know what you mean. Our thought processes involve emotions, mental images and the use of language itself as many of our thoughts are in phrases, as if talking to ourselves or others.
The emotion of thought sometimes affects how we speak, as the language associated with such emotion tends to translate into the spoken word in a less organized fashion. That is, the emotion causes us to think less "clearly", and so the language we end up choosing is usually less appropriate or less fluent. If you have ever heard the phrase "Don't speak without thinking", that is because such language attached to emotion is usually clumsy or socially awkward.
The menatl images we have, of a hamburger, of our first house, of our parents or loved ones, all translate into the specific words we use. We associate our words with the thoughts, is another way to say it.
When speaking in public or in a formal sense, we tend to think through what we want to say ahead of time, word for word, and to speak more slowly, carefully and thoughtfully. We want to be clearly understood in these situations, or we are performing, much as an actor thinks of his lines.