Source: (2010) Dissertation. Doctor of Psychology. Marshall University.

The present study examined the effects of apology sincerity and acceptance motivation on the facilitation of forgiveness of a transgression. Eighty-five undergraduates (26 males, 59 females) were randomly assigned to an Accepted Apology or a Rejected Apology condition. Participants wrote a detailed description of a situation in which they had experienced a transgression, the transgressor apologized, and they decided to accept or reject the apology. After completing their written descriptions, participants responded to a series of questions about the incident including their relationship with the transgressor, the time elapsed between the transgression and apology, the method of communication used to issue the apology, what was said during the apology and how serious they initially perceived the transgression to be. To assess apology sincerity, participants were asked to evaluate whether the transgressors: (1) acknowledged what they did was wrong, (2) accepted responsibility for their action, (3) made attempts to atone for the wrongs they had committed, and (4) gave assurances that transgressions would not happen again. To assess the consequences of the transgressions, the participants evaluated the current status of their relationships with their transgressors as well as the extent to which they had completely forgiven their transgressors. Finally, participants wrote a detailed description of their reason for accepting or rejecting the apologies offered by their transgressors. These apology acceptance and apology rejection decisions were coded as either "intrinsically motivated" or "extrinsically motivated" decisions. Four hypotheses were examined. It was predicted that: (1) accepted apologies would be significantly more likely to be characterized as sincere than rejected apologies, (2) sincere apologies would be associated with higher levels of forgiveness than insincere apologies, (3) decisions to accept an apology based on "internal" motivations would be associated with higher levels of forgiveness than decisions to accept an apology based on "external" motivations, and finally (4) the highest levels of forgiveness would be reported in those situations where sincere apologies were given to persons with "internal" motivations for acceptance. The results provided support for Hypothesis 1, but failed to provide support for Hypotheses 2, 3, and 4. (author's abstract)