Would you be willing to answer a few brief questions about PlayStation Forums?
Just found this in the MP pastepin. It may be just for multiplayer, but it's there.
"Melee counter! Press and hold TRIANGLE to counter an npc who is hitting you" - 1393.
That makes sense. In SP, they would just say hunter or infected. So does this mean co-op?
I can't do it today, I have finals tomorrow and need to study for them. I'll try it tomorrow and let you know what I find.
Tried it. Can't counter the infected.