Researchers at Ohio State University examined what happened to people who, while reading a fictional story, felt the emotions, thoughts, beliefs and internal responses of one of the characters as if they were their own – a phenomenon the researchers call “experience-taking.” The studies showed that experience-taking can, if only temporarily, affect the reader’s behaviour, attitude and decisions. Experience-taking happens spontaneously when the reader focuses on the character’s identity and forgets their own self-concept and self-identity while reading.
On the same subject:
Can a fictional character take you over? in The Guardian Books Blog