When I say that my prof can back up his claim, I mean that there are
other theorists that make the same claim.  There are no (at least very few)
"true" theories.  I myself do not think too much of this particular one, but
that does not make it wrong.  Instead of dismissing this theory, you should
find out why theorists make these claims.
        By the way, viewers are not supposed to get sexual gratification out
of horror films, they give relief to sexual tensions.  I don't know what the
difference is, but that is the theory as I understand it.
eyes