Co-operation often arises through ‘direct reciprocity’, where help is based on mutuality. A study shows that strategies that take into account several past moves of a fellow player promote co-operation. It is crucial to analyse the entire behaviour rather than just the frequency of cooperation. This emphasises the importance of a longer memory and complex strategies for sustainable cooperation.

Plön/Germany, December 09th, 2024 The ability to cooperate plays a decisive role in many areas of human coexistence – be it at work, in politics or in personal relationships. A new research finding shows how memory and the recollection of past behaviour can influence the willingness to cooperate. This finding is particularly relevant for the design of social and economic systems in which trust and cooperation are central.

In many social interactions, we act according to the principle of ‘direct reciprocity’ – we help others because we expect them to help us when we need help. Traditionally, cooperation has often been explained by simple strategies that only take into account immediate past behaviour. These so-called Memory 1 strategies, which only take into account the last action of a co-player, have long dominated scientific research. However, in real-life social situations – such as in working groups, between politicians or in interpersonal relationships – previous actions often also play a role. Especially in complex and error-prone environments, people tend to use previous experiences to make their decisions.

The most recent study conducted in this context investigates how longer-term memory in social relationships can lead to better cooperation. The researchers focussed on so-called ‘reactive-n strategies’, which are based on the past actions of a fellow player over several rounds. They found that strategies that also take into account past behaviour can stabilise cooperation and promote it in the long term. These results have important implications for our understanding of cooperation in society: they show that a long-term perspective on the behaviour of others – the ‘memory’ of previous cooperation or conflicts – can enable stable cooperation.

These findings are particularly important in dynamic social environments where mistakes and misunderstandings often occur. They explain why, in groups where long-term relationships are important (such as in teams or political partnerships), the willingness to cooperate increases when the entire history of cooperation is taken into account. For companies and organisations, for example, this could mean that a culture of trust and long-term cooperation should be promoted, in which mistakes do not immediately lead to the cooperation being broken off.

Overall, the latest findings show that memory plays a key role in promoting cooperation – not only in theoretical models, but also in everyday life and in the design of social systems. It offers a new perspective on how long-term cooperation can be successfully shaped in a world that is often characterised by short-term interests and mistakes.

Translated together with DeepL_com

Original publication:

N.E. Glynatsi, E. Akin, M.A. Nowak, C. Hilbe, (2024)
Conditional cooperation with longer memory,
PNAS U.S.A. 121 (50) e2420125121,
(https://doi.org/10.1073/pnas.2420125121)

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