Re: Measuring if/how martial arts helps one become a better person
There is some evidence that the practise of martial arts helps to modify anti-social behavour, increase self-sesteem and so on in these articles:
Laura Wilkinson, The Martial Arts: A Mental Health Intervention?; Journal of the American Psychiatric Nurses Association, Vol. No. 6: 202-206
Trulson, M. E. (1986). Martial arts training: A novel ‘‘cure’’ for juvenile delinquency. Human Relations, 39, 1131–1140.
Stuart W. Twemlow, Bridget K. Biggs, Timothy D. Nelson, Eric M. Vernberg, Peter Fonagy, Stephen W. Twemlow; Effects of participation in a martial arts–based antibullying program in elementary schools Psychology in the Schools
Volume 45, Issue 10, pages 947–959, December 2008*
BUT you can show the same benefits for most sports so maybe we're not that special after all.