The Concept of Magickal Contagion

The title really could be "The Concept of psychic Contagion In General", but I want to address this on a Coven-specific level.
  I've been thinking of something I read a couple years back, a book of experiments with meditators, monks, nuns, reiki masters etc.  (the book is called "The Intention Experiment")  They monitored brains waves during meditation or during reiki sessions, prayers etc. and found that all of these "masters" were reaching very specific brain waves that the normal populace doesn't spend any time in.  I already digress...
  One of the experiments used a couple people who just met and visited for 20 minutes, in another experiment they used spouses.  If I remember correctly,  they were separated in different rooms and one of them was subjected to some sort of stressful stimuli.  The person in the other room (their spouse, or the person they met for 20 minutes) was being monitored as well, and they registered some sort of stress-response at the same intervals it was being administered to their "partner".
  People who had never met did not register the same responses.
The partners in the next room who were not receiving stressful stimuli, did not even necessarily notice they were getting stressed.
I can't remember who taught me about the concept of magickal contagion, or if I just noticed or contemplated that it was something that occurred and needed to be avoided when possible.  The experiments in the book backed me up though.
  What this tells me is "choose your coven-mates wisely", if you get the choice!
Sometimes there are just people who are your family from the time you meet them,  but others should be avoided for the drama or psychic distress they will bring to your group.
 Before circle one of my covens used to take a moment for everyone to tell about their week so we knew where they were coming from, and what energies they might be bringing.  Not a bad idea!
  Don't get me wrong, everyone has bad years, and that doesn't mean they should be excluded, but perhaps if they were new to the group, they should get their shit sorted out before joining the coven.  Once they are in, they should all be helped to the fullest degree.  If someone is having a bad year, do workings to make it better.  This seems like it should be a given.
  I think that's it for today. A good concept for Candlemas I guess.  Spring cleaning isn't just for your house folks!
love and light,
Nox