I may be wrong, but I think that you can find some hints for your question by reading the seminal book of Fouler, J. (1981). Stages of faith: The psychology of human development and the quest for meaning . New York:  Harper & Row.

You might want to add Psychology of Religion to your topics.Check out the Society for   the Scientific Study of Religion and its journal, and Division 36 of the American Psychological Association, the Society for Psychology of Religion and Spirituality. If you have access to Psychological Abstracts, check there for resources.

You can find a variety of measures of spirituality and religion  in Measures of Religiosity, 1999 by Peter C. Hill and Ralph W. Hood Jr., Religious Education Press.

I do wonder whether you can find anything meaningful with a correlational study. How would you measure interpersonal communication in a dynamic, real-life way? Will you observe actual communication? In my book the gold standard for interpersonal research would be something like The Structural Analysis of Social Behavior, which involves observation and Markov Chain Analysis of the communication patterns. I doubt that Seligman's research would be relevant, but would suggest checking out some recent textbooks in the Psychology of Religion to guide your theoretical background.

Quasi experimental:  Assess spirituality -- observe interpersonal interactions with confederates or virtually.

Spirituality leads to decline in violence (physical, verbal, and the like), noise, show-off, and othering (social, cultural, racial, ethnic)

Hi Elizabeth, When I started on RG, I asked some similar questions. I was trying to look into Spirituality/Religiosity and Suicide. You can see my previous posting and comments  given on what they advices I got on "spirituality" and "religion". I actually appreciate those inputs. Hendrika's suggestion of Hill (1999) is excellent, although it may be a bit expensive and it's about 500 pages thick. The disadvantage for me was a lot if not more or all (Hendrika, pls correct me if I am wrong) have some element of Christianity in the questionnaire. So, if you are targeting Western Christianity, it's excellent. I haven't seen such a complete compilation. However, if you are targeting other religions or other countries besides US/Canada and Europe, then you may need one questionnaire that is religion neutral. There are not many though. You need to be careful on Western Christianity practice and Asia Christianity practice as a lot of Chinese in Asia has some roots from China, thus they are some mixture with Chinese cultural elements. For inter-personal comm., I am not sure which aspect you are trying to measure. I suppose if you have a good instrument, you can measure religiosity/spirituality on one instrument and inter-personal comm. as another instrument. And for those tricky or grey area, you may tackle with Phase Two qualitative approach, or you can combine all as a mix-type questionnaires by putting in some thematic approach type and open-ended questions. For info., I am not as familiar with  inter-personal comm. areas. If you like some sample on Hill (1999), I don't mind scanning some for you, and I have two measures of level of religiosity which is religion-neutral (i.e. it's validated for the world's four largest religion including secular/atheists). Let me know.