[The contribution of persuasion social psychology to the retention of donors: models to elaborate mailing to the donors].

The supply of blood cell products required from the National French Blood Institute (Établissement français du sang [EFS]) relies upon regular blood donors. Contact with donors, tailored to individuals as much as possible, helps them to donate on a regular basis. To communicate as efficiently as possible, the content of the mailings has to be adapted to individuals, each according to his/her motivation and the way he or she perceives and processes the information. Within the context of a research program conducted with the Psychology Department of the University of Caen Basse-Normandie, persuasive theoretical models from social psychology have been tested. These models allow adapting messages according to various combinations of types of information processing, motivations and content of the messages. Different types of mailing invitations have been sent to 1987 donors from the Normandy database, requesting them to donate blood. Every experimental letter worked better than the standard EFS letter (which was used as the "control" letter) in terms of effective blood donation after reception of the letter. Some of the letters are more efficient in motivating donors than others. When the systematic type of processing (deep and thorough processing) is activated it appears important to supply elaborate content. On the contrary, when a heuristic type of processing (fast and superficial) is activated, adaptation of the content is less essential. Last but not least, the nearness of the last blood donation plays a key role.