McCullough, M. E., Kilpatrick, S. D., Emmons, R. A., &Larson, D. B. (2001). Is gratitude a moral affect?. Psychological bulletin, 127(2), 249.
Gratitude is conceptualized as a moral affect that is analogous to other moral emotions such as empathy and guilt. Gratitude has 3 functions that can be conceptualized as morally relevant: (a) a moral barometer function (i.e., it is a response to the perception that one has been the beneficiary of another person's moral actions); (b) a moral motive function (i.e., it motivates the grateful person ...