Behavior inertia of individuals promotes cooperation in spatial prisoner's dilemma game

Cooperation is ubiquitous in real world, even in a fierce competitive environment, which is in contrast with natural selection theory. To address this contradiction, many scholars pay more attention to researching the emergence and maintenance of cooperation. In recent decades, lots of mechanisms about individual behavior are put forward to promote cooperation in spatial prisoner's dilemma game. However, fewer studies focus on the effects of behavior inertia on cooperation. For example, insistence is the key to habit formation, and every extra day you insist, the more motivation you have to keep going, the bigger the inertia of the same behavior is, and the weaker the intention you have to make a change. In other words, it is easier to insist than to change. To this end, we propose a new mechanism, called inertia mechanism of individual behavior to explore the evolution of cooperation, in which each player's behavior inertia relies on the persistence of his/her current strategy: the longer the strategy duration is, the bigger his/her behavior inertia is, and, as a result, the weaker the willingness he/she has to update strategy. Moreover, a reinforcement parameter, alpha, which characterizes the degree of the impact of the strategy persistence on the behavior inertia, is introduced. The results of numerical simulation show that our inertia mechanism can promote cooperation effectively, compared with the traditional model, and the mechanism performs better with the decrease of alpha.