In their book on Rumor Psychology Nicholas DiFonzo and Prashant Bordia mention the concept of “Matthew Accuracy”. Deriving its name from the principle in the Gospel of Matthew that “to the one who has more will be given, but from the one who does not have even the little he has will be taken away”, Matthew Accuracy denotes the tendency of truthful rumors to become more truthful, while false rumors tend to become more false (pp.152-4).
If it could be confirmed that this same tendency applies in cultures more closely related to that in which the Gospels were written, I wonder whether this principle might not be useful to historians evaluating the developing Gospel tradition. In essence, might it be arguable that those sayings and stories that tend to become increasingly fantastic and to develop in predictable ways according to the tendencies of the tradition are less likely to be historically accurate, while those that either persist in their essential details or accumulate additional details that seem historically plausible and/or defy the tendencies of the developing tradition are more likely to be historically accurate? I am not suggesting that this is an entirely new idea, but it might be possible, on the basis of research into the psychology of rumor, to turn what may have been a “hunch” for historians up until now into a solid working principle with strong theoretical underpinnings.