If you've read Malcolm Gladwell's "Blink", you know how human behaviors are often instinctive - to the point that you can't control your "tell" (to use a poker term).
Gladwell describes "SPAFF" (Coan & Gottman) which breaks down human reactions into emotional states. It's not an easy technique to master - but Gottman can predict, with uncanny accuracy, whether a couple will be divorced with 5 years after listening to a few snips of conversation.
A descripition of SPAFF (Specific Affect Coding System) can be downloaded at researchgate.net. I highly recommend it.
The Codes (Emotional Categories)- function (purpose)