Classifying different methods for quantifying the Prisoner's Dilemma Game.

What is it about?

The Prisoner's Dilemma (PD) Game involves a choice between options to cooperate (providing the greatest benefit to a group) or defect (providing the greatest benefit to oneself). The PD game is most commonly presented as a 2 (players) by 2 (options) matrix with 4 outcomes (Temptation, Reward, Punishment, Sucker) for each player. Historically, many efforts have sought to quantify the PD with a single number, or index. The current research first classifies the different existing indexes into 6 families based on common properties of the indexes. Finally, we validate the classification scheme with a meta-analysis of the relationship between indexes of the PD and cooperative behavior.

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Photo by Beth Macdonald on Unsplash

Photo by Beth Macdonald on Unsplash

Why is it important?

First, this research provides an organizational framework for understanding the ways the PD game can be indexed. We believe this will be useful and informative to future researchers in selecting which index to use in their own work and avoiding over-lapping efforts to create new indexes that are redundant with past efforts. Second, the six families of indexes can help to provide researchers a framework for understanding the motivations for cooperation in social dilemmas and further examining those motivations in relation to individual, physiological, situational, and cultural differences. Future directions are described in greater detail in the article.