While speaking with a client of mine from Thailand recently, I raised my eyebrows at one point because I hadn't heard what she had said. Puzzlingly, she just nodded. Then I said, "I'm sorry, I didn't understand the question." After she repeated the question, she told me that she had thought I was answering "yes." It led to some interesting dialogue about facial expression, cultural body language and meaning, and led me to a several interesting articles regarding cultural gestures and norms. Here are a few that I found.