It is quite possible to hold a conversation without speaking. Simply raising an eyebrow implies you question what your conversation partner is saying. Looking out a window can imply boredom, a desire to move things outside or simply a way to steer the conversation to something you are looking at. Crossing your arms and closing your posture shows you are defensive and suspicious of the other. Many facial expressions are universal across cultures: a sad man looks similar everywhere.
This demo provides an example of what can be conveyed by eye gaze.
As 3D models become more complex, games are able to model more of these elements. Top level games already use lip synching to tie in the spoken dialogue, facial expression and some gestures. However, since most games revolve around combat, most of the animations will be dedicated to combat moves. In addition, expressions and gestures are usually only displayed in cinematics. One exception is on-line role playing games where players can stand around and put their characters though a wide variety of postures, either to pass the time or enhance their communication with other players.
InteraQuest is evaluating methods of tying gestures and postures to the player character’s emotional state. The player uses real-time controls to indicate his current state and the game modifies the character’s look and its voice to accommodate this. The goal is to provide visual feedback to the use of the controls.