0 past simple and past participle of defect
1 to leave a country, political party, etc., especially in order to join an opposing one:
Most disturbing is the finding that once players learn that their opponent has either cooperated or defected, almost all defect.
This point represents sequences of three trials in which there were three defections and the same opponent defected on each trial.
It is a particularly powerful barrier to intelligence sharing because of the difficulties inherent in determining ex ante if a partner has defected.
In other words, we assign cooperation the same payoff it would receive if everyone also defected.
This suggests that voters unhappy with general government performance simply defected to the other major party (as predicted by a retrospective voting model).
In short, junior members defected to help their electoral position.
Employers defected from wage moderation agreements.
When the relatively global histories matched the relatively local set of contingencies (the computer's strategies) subjects cooperated; when the global histories contradicted local contingencies they defected.