"22 Division I FBS teams currently use helmet-sticker rewards. Yet these decorations are much more than small tokens of thanks. They embody a rite of passage, with a player’s status among his teammates measured by how heavily adorned in stickers his helmet becomes during the course of a season.
Now, a study published this month in the online journal PLoS ONE, has given a fresh perspective on this practice: When small rewards become visible trophies of status within a group, male players change their approach in competition, sacrificing their own best interest to serve the needs of the team."
- Wired, The science behind college-football helmet stickers