Who is Eleanor Vance? Why is she chosen for Dr. Montague's project?

Eleanor Vance is a young woman who once had an experience with a poltergeist in which rocks rained down on her childhood home. This is why she is chosen for Dr. Montague's project, because he believes her to be sensitive to the paranormal. Eleanor spent eleven years nursing her dying mother and now lives with a sister who dislikes her and only puts up with her because she feels she has no choice.