clipped from www.washingtonpost.com

For 25 years I worked as a paid observer. I was a special agent for the FBI specializing in counterintelligence -- specifically, catching spies. For me, observing human behavior is like having software running in the background, doing its job -- no conscious effort needed.

When I am asked what is the most reliable means of determining the health of a relationship, I always say that words don't matter. It's all in the language of the body. The nonverbal behaviors we all transmit tell others, in real time, what we think, what we feel, what we yearn for or what we intend.

When it comes to relationships and courtship behaviors, the list of useful cues is long. Most of these behaviors we learned early when interacting with our mothers. When we look at loving eyes, our own eyes get larger, our pupils dilate, our facial muscles relax, our lips become full and warm, our skin becomes more pliable, our heads tilt. These behaviors stay with us all of our lives.