Jordi Brandts shares an overview of different lab experiments regarding human behavior and its relation to communication, which is the common factor in all of them. This central thesis is that communication matters and it affects different issues of our nature. He describes the agent-based model used in these experiments and the concepts that it includes for a better understanding of the experiments. Brandts illustrates the first communicational experiment, regarding the effects of punishment and communication on human cooperation. He justifies this connection by analysing a study called "Counter-punishment and norm-communication and accountability" which is the second stage of the first experiment.

After punishment, a third stage was created, regarding counter-punishment and communication. How can one revive communication once it has decayed? Jordi answers this question by how communication works and affects contract design. He provides plenty of data of the results of the experiments with the different communication treatments he speaks about. He finishes by giving some general lessons he has learned from the study of communication in human beings.