Unlike most other subjects listed here, Paranormal Studies never left Hogwarts. Despite that, the class course has not grown and the curriculum has not changed even as new research finds alternative theories on life after death.
In the 1980s, muggle students from the University of Wisconsin-Madison discovered the ghosts of muggles (although they did not know of the magical aspect of their discovery), defying wizard beliefs that only wizards can return as ghosts, but that only wizards could see ghosts. They also created technology that could track ghosts and interact with them physically.
Wizards have disregarded their research as it did not agree with what wizards already knew about ghosts.
Ghosts residing in Hogwarts too dispute theories taught in the class, but they are looked over as they are dead and wizards believe they cannot gain much more information than they retained in life.
As a result, the subject is closer to a club than a class, discussing theories on ghosts not yet proven and even proven wrong and famous ghosts or paranormal events. Hogwarts ghosts are often asked to be guest speakers but they rarely come by otherwise.
Numbers of students signing up for the class have dropped dramatically in recent years and administration is considering canceling the class altogether.
Due to all of this denseness, wizard youth are increasingly ignorant about ghosts. On the rare occasion that one might leave the wizarding world, he or she will not be prepared for the state of the muggle world, as ghosts, muggle or wizard, have become widespread across the globe since an unexplained phenomena in 2004.