What's the equivalent to a "poker face" in an online game setting?

Let's face it, aren't we all walking around with a poker face? Maintaining an unreadable demeanor is a crucial aspect of poker and it appears to be life in general too. Poker face is often referred to as maintaining a "neutral expression" or "stoic demeanor. While this is traditionally the case, it's obviously not visible in an online setting. How do you avoid visible emotional cues online especially when concealing one's intentions in many tabletop games is essential for success?

This question brings me back to the longevity of board games and how authentic it is to play face to face.  The subtleties of a simple poker face in a game is timeless. Just like a poker player would maintain a stoic demeanor to conceal their hand in a traditional card game could emoticons and an avatar or one's behavior online convey actual hidden intentions? It seem ludicrous. How would a player know if you are bluffing or concealing your strategy?