Oxford psychologists in an Anglican country did some surveys and have recommendations for Catholics: People who recall being absolved of their sins are more likely to donate money to the church, they write Religion, Brain and Behavior.
Academics from Royal Holloway and the University of Oxford assigned participants two memory tasks. In the first, they were asked to privately recall a sin that they had committed in the past, while in the second, they recalled attending confession for this sin or imagined doing so, if they had not confessed in reality.