For a 2010 study, social network gurus James Fowler and Nicholas Christakis had people play a series of “public goods” games with different groups of strangers.
In these games, subjects staked with a modest amount of money can give whatever they want to a communal pot of money that is then tripled in value and split evenly.
After each round, everybody learns who gave what.
Usually in these games, people start off trusting each other to some degree.
Then some players inevitably try to get something for nothing, or next to nothing, and their free riding eventually kills trust and drives donations into the ground.
In Fowler and Christakis’s study, however, subjects dealt with a new group of players every time.
Each round was a fresh start and a one–shot deal, so neither reputation nor reciprocity had any pull.
Nevertheless, the players’ contributions in any given round rose and fell according to how generous their fellow players had been in earlier rounds.
The more those previous partners had given — indeed, the more that previous partners of those previous partners had given — the more trusting and generous subjects would be with their new group.
Even without concern over developing a reputation, or an opportunity to reciprocate, trust ripples out.
Trust can evaporate just as easily.
Ironically, punishments for not cooperating can backfire precisely because they imply low expectations for trustworthy behavior.
If people could be trusted, after all, then no sanctions would be necessary.
In one recent experiment, people played two rounds of a trust game.
Some initially played with punishments for violating trust and then played a second round without these sanctions.
Everyone rated how much they trusted their fellow group members on a sliding scale.
People who played under the threat of sanctions cooperated more, but trusted each other less than those who played without sanctions.
When the sanctions were removed, the value of trust dropped even further and cooperation among these players took a nosedive.