I don't even know what my problem is called, so I can't research literature on it. I'm hoping someone can point me in the right direction. I have a little experience with sentiment analysis, but what I want to do is more specific. Rather than evaluating the general sentiment of a body of text, I want to evaluate the sentiment about a particular subject in a body of text. For example, let's say I have an article about President Obama. One sentence says
President Obama arrived in Florida and saw the horrific destruction left behind by the hurricane.
While the general / overall sentiment of this sentence would like be negative, Obama is spoken about fairly neutrally. This is what I mean by about-sentiment. I want to evaluate (with a computer) how positively or negatively the text speaks about a specific subject.
What is this called? Is there literature on it? How can I proceed?