The NY Times ran a great article today on commitment detailing psychological findings that indicate that while some people may be more naturally inclined to resist temptation to break commitment, people can also train themselves to raise their feelings of commitment once they are in a relationship.
The article cites a few studies on reactions to possible relationship threats when parties are in committed relationships. I found the study by a McGill psychologist John Lydon most interesting. In the study, married men and women were asked to rate the attractiveness of people of the opposite sex in a series of photos. Married men and women gave the highest ratings to people we typically think of as attractive. However, the same individuals were later shown similar pictures and told that the attractive person was interested in meeting them. In this case, participants often gave those pictures lower scores than they had the first time around.
Lydon mentioned that this may be a defensive mechanism that participants used to remain faithful to their commitment. When the participants were attracted to someone who may threaten their relationship, they instinctively compensated by lowering their assessment of the potential threat.
Read the full article here.