The way I've come to understand it is that whenever your unique IP address views a page, it adds to the tally of page views. However, that unique IP cannot log a new page view until another post is made in the thread.

Topic Creator posts topic and views it. Page Views: 1.
Topic Creator refreshes topic. Page Views: 1.
Forumer A views topic. Page Views: 2.
Forumer A replies to topic and views it again. Page Views: 3.
Topic Creator views topic. Page Views: 4.
Forumer B views topic. Page Views: 5.
Forumer B replies to topic and views it again. Page Views: 6.

And so on.

-Grey