It seems to me that the forum member who participates in a thread approach the experience invigorated with much the same attitude, as does a boxer entering the ring for a fight. See quotes below from:
http://www.the-brights.net/forums/index.php?showtopic=4031
"Its like our brains instinctively assume the person we are speaking with, but can not see, is a knife wielding assassin - unless proved otherwise visually. Healthy and stable communication evolved with visual cues as a foundation - we fly into trouble without them."
"I've noticed the same phenomenon. Discussion board postings quickly regress to vitriolic that none of us would use in face-to-face discourse."
We have a gut feeling about some things because our sense of correctness comes from our bodies. When Newton provided us with his theory of physics we could "feel in our gut" the correctness of much of it because he was using such concepts as acceleration, momentum, distance and velocity all of which we knew because we could intuit them, we could "feel in our gut" these concepts. Such was not the case when the physicist attacked the problem of quantum physics. Who has a gut feeling for the inner workings of the atom?
"To see a butterfly, as in the garden, we have to project a nontrivial amount of imagistic structure onto the scene. We have to conceptualize the boundaries of the garden as a three-dimensional container with an interior that extends into the air. We also have to locate the butterfly as a figure (or trajectory) relative to that container, which serves as a ground (or landmark). We perform such complex, though mundane, acts of imaginative perception during every moment of our waking lives."
"Our bodies define a set of fundamental spatial orientations that we use not only in orienting ourselves, but in perceiving the relationship of one object to another."
"The study of spatial-relations concepts within cognitive linguistics has revealed that there is a relatively small collection of primitive image schemas that structure systems of spatial relations in the world's language."
"The embodied-mind hypothesis therefore radically undercuts the perception/conception distinction. In an embodied mind, it is conceivable that the same neural system engaged in perception (or in bodily movement) plays a central role in conception. That is, the very mechanisms responsible for perception, movements, and object manipulation could be responsible for conceptualization and reasoning. Indeed in recent neural modeling research models of perceptual mechanisms and motor schemas can actually do conceptual work in language learning and reasoning."
Let us say that in early childhood I had my first fight with my brother. There was hitting, shoving, crying, screaming, and anger. Neural structure was placed in a mental space that contained the characteristics of this first combat, this was combat #1. Six months later I have a fight with the neighbor kid and we do all the routine thing kids do when fighting.
This is where metaphor theory does its thing. This theory proposes that the characteristics contained in the mental space, combat #1, is automatically mapped into the mental space that is becoming combat #2. The contents of combat #1 become a primary metaphor and the characteristics form the fundamental structure of mental space combat #2.
This example applies to all the experiences a person has. The primary experience is structured into a mental space and thereafter when a similar experience is happening the primary experience becomes the primary metaphor for the next like experience. This primary metaphor becomes the foundation for a concept whether the concept is concrete experience or abstract experience.
What I am saying is that for some reason the Internet discussion forum member considers engaging in a forum thread is a competition, it is a combat, and the primary combat metaphor is mapped into the mental space of this forum experience and thus the forum experience takes on the combat type experience. That is why lots of forum activity gets very combative. (I think).