Retelling of stories increases bias

Interesting experiment shows that the retelling of stories increases conflict and bias.

For their study, which featured 196 undergraduates, the researchers created a narrative about a dispute between two groups of young people. It described four specific points of tension, but left purposely ambiguous the issue of which party was the aggressor, and "depicted the groups as equally blameworthy."
Half of the participants read a version of the story in which the two hostile groups were from two Maryland cities. The other half read a version in which one group was from the city of Gaithersburg, but the other was identified as "your friends."
Participants were assigned a position between one and four. Those in the first position read the initial version of the story, and then "re-told" it in their own words by writing their version of the events. This was passed on to the person in the second position, who did the same.
The procedure was repeated until all four people had created their own versions of the story. Each new version was then examined for subtle shifts in emphasis, blame, and wording.
The results: Each "partisan communicator" -- that is, each student who wrote about the incident involving his or her "friends" -- "contributed small distortions that, when accumulated, produced a highly biased, inaccurate representation of the original dispute," the researchers write.

Standard disclaimer -- that American undergraduates might not be the best representatives of our species -- applies. But the results are not surprising. We tend to play up the us vs. them narrative when we tell stories. The result is particularly interesting in light of the echo chamber that Internet-based politics has become.
The actual paper is behind a paywall.