I was waiting for Val to answer this, but I'll give it a shot. The relevant CFAR unit is called "againstness." You can think of sympathetic dominance as related to (being?) a sensation of "againstness," e.g. when you get angry during a heated argument your feelings are directed against the person you're arguing with. Val gave us both mental and physical techniques for releasing againstness ("fighting againstness" is kind of againsty). The mental techniques (which I'm just going to quote verbatim from the worksheet; hopefully Val won't mind):

• Gratitude: appreciate the opportunity to practice releasing againstness in adverse situations. (Also, appreciate the pleasure of PNS activation to help stabilize it.)
• When againstness is related to others:
  • Empathy: model the other person in enough detail to appreciate likely reasons why what they're doing is, to them, the most sensible thing they could be doing in that moment.
  • Connection: intentionally increase your sense of tribal togetherness; see the other person as a fellow human being and wish to help them realize their full potential.

That might sound a little woo but the above is intended to be a description of specific mental algorithms that you can actually run. The physical techniques:

• Open your posture. Shoulders back, spine straight & upright, head balanced on spine, belly exposed.
• Breathe. Deeply, smoothly, gently, and low - without pushing it low or sucking air in.
• Relax. Especially the hands, arms, shoulders, and eyes. (Smiling sometimes helps!)

I've found gratitude together with the physical techniques to be reasonably effective and have used them several times since the workshop already. I have not extensively tried using empathy or connection.

As for tests, one of the reasons it was valuable to learn this material at the workshop is that Val is very good at spotting the physical indicators of sympathetic dominance. Accordingly, the againstness unit had a practical component where Val or one of the other instructors would stress out participants in various ways in order for them to practice using the techniques above, and Val would diagnose to what extent the techniques were working. So testing yourself doesn't sound easy to me. If you just want some tips for noticing when your SNS is dominant, try looking for the following:

• hunched shoulders
• rubbing the neck
• positioning arms to protect the belly
• tensed muscles

Unfortunately I don't think it's easy to notice that you're doing these things.

Each of the CFAR worksheets also included a list of further resources. For the againstness unit, the further resources were the Wikipedia articles and two papers:

Fredrickson, B.L., Mancuso, R.A., Branigan, C., & Tugade, M.M. (2000). The undoing effect of positive emotions. Motivation and Emotion. 24, 237-258. http://goo.gl/AP920

Heinrichs M., von Dawans B., and Domes G. (2009). Oxytocin, vasopressin, and human social behavior. Frontiers in Neuroendocrinology, 30, 548-557. http://goo.gl/kGaz6