for more natural expressions, asymmetry is important, both in facial geometry and articulation. Most Poser models have separate L and R controls for eyebrows and eyelids, but most don't have such controls for the mouth. Any tips for producing mouth shapes which are asymmetric?

You can split morphs in left and right in Poser by clicking the little triangle next ot a morph target dial, then selecting "Split morph..." from the popup menu.

thank you!

The DAZ characters have separate left and right dials for some expressions. I always try to add asymmetry for the reasons you give. You can also do things like using different dials to give the same effect: for example, use EyebrowArchL and EyebrowRaiseR to raise the eyebrows (not sure of the exact names, not near a copy of Poser, but you get the idea).

The morph splitting feature is only in later versions of Poser, by the way - it's definitely in P6, not sure about 5, not in P4 or below.

All my XprssnMagics give you thousands of expression combinations, and lots are asymmetric. P4FemXprssnMagic is here in the Marketplace and V3, M3, Aiko3, V2, M2 are over at DAZ. HTH - Elisa/gryffnn