Are the cooperation maintained when the classic Prisoner’s Dilemma (PD) game is repeated over many rounds? Is male pairing almost twice as good as female pairing? Both findings were reported in a very large American experiment published more than half a century ago. Now, an experimental study using stricter methodological and statistical techniques and larger economic incentives confirms two major findings in the UK population, despite significant changes in the status of women and gender attitudes in the subsequent decades. A research team at the University of Leicester, UK – Andrew Colman, Briony Pulford and Eva Krockow in a computer-controlled experiment The cooperation was investigated, in which 150 men and women played different PD games 300 times in a fixed pair. This work was published in the journal Acta Psychologica.
PD games represent two strategic structures of interactions in which two people do better than existing flaws (not cooperating), but each attempts to flaw in order to get their own best. Reward and make another person pay for the worst possible. According to game theory, rational players who know in advance the round they are going to play should be flawed in each round, because defection is better than the cooperation of others or flawed cooperation, but experiments will always find a high level of cooperation.
The decline in cooperative PD has been widely reported in the literature, but in most experiments, only a small number of repetitions were used. The significant decrease was not confirmed by statistical time series analysis and could be a simple final effect. It was determined many years ago that players tend to reduce cooperation when they see eventually approaching, which may be mistaken for a steady decline in cooperation due to repetition. Leicester researchers confirmed the final game effect of all six groups they studied (see annex), although time series analysis confirmed that none of the overall declines in these groups were significantly reduced.
American scientists reported initial decline in collaboration, followed by steady increase in collaboration, but this could be attributed to unintentional quasi-form effects in their research, Leicester researchers said. U.S. participants were asked to calculate their losses and benefits at the end of the 25 round, which may have created a quasi-form effect, thus reducing collaboration.
Leicester researchers also replicated the huge gender differences originally discovered in the United States in the 1960s: women paired with women were much less than men paired with women, while mixed gender pairs showed an intermediate level of collaboration. This gender difference is a difficult problem. It is much larger than most psychological gender differences and is contrary to traditional sexual role stereotypes. Players adapt their level of cooperation to the gender of their colleagues, because in the UK experiment, players cannot recognize the gender of their colleagues.
Professor Coleman’s comment on science said: “Our most important finding is that repeated collaborations are often considered a misunderstanding, which may be due to the expectation that the joint defection in the game theory should be steadily integrated As players understand the game better through experience. Obviously not. Regarding the gender differences in collaboration, Professor Coleman said: “Some researchers attribute it to women’s risks, but this is not right because in The same difference will also occur in repetitive chicken games, in which case greater risk aversion will make women more cooperative than men. In PD, cooperation is likely to be the worst reward, but in chickens, It’s a defection, and the risk is probably the worst reward. “So, how do you explain the gender difference? According to Professor Coleman, “This may be related to reasons why women are more socially oriented and therefore care more about relative returns than absolute returns than men. In PD and Chicken, defection is guaranteed not to be worse than your colleagues. The only way to do it.”
Journal Reference and Image Credit:
Colman, Andrew M., Pulford, Briony D., and Krockow, EvaM. “Continuous Cooperation and Gender Difference in Repeated Prisoner’s Dilemma Game: Some Things Never Change.” Acta Psychologica 187 (2018): 1-8. doi:10.1016/j.actpsy.2018.04.014
About the Author
Dr. Andrew Colman
professor
Andrew M. graduated from the University of Cape Town, where he was appointed as his first lecture position and then gave lectures at Rhodes before moving to Leicester. His main research interest was judgment and decision-making, game theory and experimental games, cooperative reasoning, cooperative evolution, and psychometrics. His author is over 160 peer-reviewed journal articles and several books, including Oxford Psychological Dictionary (4th edition, 2015), Crash courses in Windows SPSS (4th edition, co-authored with Briony D. Pulford, 2008), Game Theory and Its Application in Social and Biological Sciences (Second Edition, 1995), What is psychology? (3rd edition, 1999), Facts, fallacies and fraud in psychology (1987). He edited Routledge Encyclopedia of Companion Psychology (1994), 12 volumes Langman Basic Psychology Series (1995).
Dr. Briony Pulford
Associate Professor
Briony Pulford is an associate professor of psychology who has worked at the University of Leicester since 2004. She has led the multidisciplinary Leicester Judgment and Decision Research Group since 2010. Her interests lie in social and cognitive psychology. Briony’s research covers many areas of judgment and decision making, specific interests in collaboration, team reasoning, game theory, overconfidence, confidence, trust, moral judgment, and ambiguity aversion. Her PhD is concerned about overconfident judgment, but since then, she has been studying how people view and explain the confidence and uncertainty of communication and how this affects decision-making. She has been involved in testing heuristic confidence and researching how people can use information about other people’s confidence. Briony said in her game theory study that one of her most exciting research moments was finding that collaboration in the repetitive prisoner dilemma game did not decline, and that the classic findings of Rapoport and Chammah are likely due to methodological issues and Quasi-Endgame effects only cause a decrease.
Dr. Eva Krockow
Assistant Professor
Dr. Eva Krockow is a lecturer (assistant professor) at the University of Leicester and leads the Neuroscience, Psychology and Behavioral Health and Wellness Research Group. Her research focuses on understanding the core principles of cooperation and defection, and she studies it by modeling human choices in abstract experimental games. Recently, EVA has been applying this theoretical knowledge to the areas of medical decision-making, including antibiotic use. She is particularly interested in perceptions of risks and uncertainties in antibiotic treatment choices and collective intelligent approaches to optimize health-related decisions. Part of the work of EVA also involves the analysis of cross-cultural differences in decision making. Recently, her international studies have brought her to Japan, Sri Lanka and South Africa. EVA uses a variety of methodological methods in her research, including qualitative interviews, quantitative experiments, and computational modeling. Eva is passionate about science communication and has written regular blogs, including decision-making research in Today Ithical (https://www.psychologytoday.com/gb/blog/stretching-wareory) .
Main image credit: Giulia Forsythe, Flickr
