Cooney, Donald F. Changes in Attitude and Social Involvement Among Returned Overseas Volunteers. (dissertation) Bryn Mawr, 1983.
Summary: The author sent an extensive (25 pages!) survey to returned volunteers who had worked with MCC, IVS (International Voluntary Service), and LAOS (an ecumenical volunteer and training agency funded by a Methodist layman), hoping to find out if and how volunteers attitudes change because of their experience, what specific elements of the experience aided change, how volunteers could better share their new knowledge with those back in the US, how people who don't/can't go overseas can gain some of the same knowledge.
Concludes that "there was a definite change in attitude of a large percentage of volunteers, and there is evidence of increased post-service involvement by many of these volunteers in social action, especially on international issues." No particular group (in terms of age, gender, sending organization, etc) reported more change than others.
Suggestions of volunteers for improving the experience pertained especially to orientation/preparation/training, maximizing intensity of volunteer experience by making volunteer responsibilities well-defined and meaningful, promoting endurance of change, assistance with transitions, continuing education.
Methodology: Names of volunteers were gathered with help of the three organizations. Questionnaires were sent to 802 MCC volunteers (411 responded), 531 IVS volunteers (245 responded), 235
Results: Pages and pages that I can send you if you're interested.it's interesting, but obviously the group looked at in this study are not STMers in the sense you guys are looking at.