Tatsuhiro Shichijo

An Experimental Investigation of a Third Person Enforcement in a Prisoner’s Dilemma Game

We experimentally study the effect of a third-person enforcement on a one-shot prisoner’s dilemma game played by two persons, with whom the third person plays repeated prisoner’s dilemma games. We find that when the third person can observe these two persons’ play, the possibility of the third person’s future punishment causes them to cooperate in the one-shot game.

Third Person Enforcement in a Prisoner's Dilemma Game

We theoretically study the effect of a third person enforcement on a one-shot prisoner’s dilemma game played by two persons, with whom the third person plays repeated prisoner’s dilemma games. We find that the possibility of the third person’s future punishment causes them to cooperate in the one-shot game.

Properties of learning models in collective action: Rationality of backward-looking players

This article intends to clarify properties of learning models in simulation studies and to conduct a comparison of preceding learning models. Learning models are often used in many simulation studies, but there is no uniform rule of learning. We introduce three technical properties (monotonicity, condition of probability, neutrality) and three rational properties (rationality is fixed situations, rationality in first order stochastic domination, rationality with risk preference in stocahstic situations). We examine Michael Macys model, the Erev & Roth model, and some others. We find that these models have different properties. Though learning is treated as one of the solutions of social dilemma from the results of Macys model (Kollock, 1998), Macys model is peculiar learning model. Learning is not always a solution of social dilemma. A comparison of learning models from a uniform point of view clarifies the properties of each model, and helps to probe conformity of a learning model and human behavior.