Perhaps print some of these out so she can learn more - its not something people naturally understand so its probably normal for people to think what your family / aunt thinks:
http://www.psychcongress.com/article/treatment-negative-and-cognitive-symptoms-schizophrenia-13473
http://www.psychiatrictimes.com/schizophrenia/negative-symptoms-schizophrenia-update-identification-and-treatment