Originally Posted by zachvac
The problem I think is that someone with a monster or someone trying to pull off a bluff would be breathing hard.
I could be wrong here, but from what I've observed (and read), the responses are actually fairly different for the average player.
If someone's trying to pull off a big bluff, they're more likely to hardly be breathing at all. They'll usually be very conscious of everything they're doing, including something as simple as breathing, and they'll overcompensate as a result.
The motivation is the fear that if they give even the smallest
sign their opponent will them. Somehow, 'breathing normally' gets put into the "Ohshit it'll make them call"
category. A player that's bluffing will rarely be able to engage you in conversation either, based on the same principle: they'll be too scared that something they say will make you call.
If, on the other hand, you can see someone's pulse pounding away in their neck, it's usually a sign of genuine excitement: they usually have a monster hand.
Breathing heavily works along the same lines - the player is usually far too busy trying to control their stupid grin to worry about how they're breathing or their pulse rate.