The range of expressions that people go through when they talk is remarkable (although Nicole is a lot more expressive than some people). But even for a shy person, getting them to talk will take their mind off the camera. If the camera is sitting on a tripod and the person can look at your face instead of the cold eye of the camera, the model will be more likely to give you warm and natural expressions. If you need the model to look right into the camera, you might want to either hide behind it, while keeping up the conversation, or simply ask them to look into the camera, but keep up the conversation to keep them feeling connected to you.
Bottom Line: Consider talking with the person you are photographing.
105mm, f8, studio softbox on right, reflector on left