Forgiveness is a multidimensional intrapersonal relational concept. It is a reasonably stable, motivational state that exists when a person experiences positive cognitive, affective, and/or physiological responses toward offenders and/or their transgressions. The state of forgiveness follows a choice to forgive that occurs sometime during the forgiving process.
Forgiving is a multidimensional, motivational process that reflects overall increasing positive changes in cognitive, affective, and/or physiological responses toward offenders and/or their transgressions. The process has a starting point following a transgression. The process may be interrupted or reversed. The process may or may not result in a stable state of forgiveness.
We can also think of forgiveness as a personality trait or disposition. Some writers refer to this as forgivingness. The idea is that some people routinely forgive more than others-- as if it were part of their character. Here's a quote from Sutton & Thomas (2005, p.34).
Dispositional forgiveness is a personality trait that reflects a tendency to respond to many transgressions with positive cognitions, affects, and/or physiological states within a short time
YouTube video of Ev Worthington and his REACH model.
You will find more references to the research studies at the end of the article. Click the link for the full article with references.