Sources of Irrational Behaviour. Three Essays on Theory and Experimental Evidence

This thesis investigates aspects of human behaviour that can be considered irrational from an economic point of view. Potential reasons for three persistent behavioural patterns in economic interactions are investigated: Altruism, discrimination, and punishment of deviant (“immoral”) behaviour. For the first two patterns, this thesis reports the results of dictator game experiments with young children in primary schoolsin Vancouver, BC, Canada. To understand altruism, the thesis looks for potential reasons why children share resources with genetically unrelated others. It shows that socialization in a particular cultural environment, indicated by the language children speak at home, influences children’s sharing behaviour to a large extent. The second part investigates discrimination among children belonging to different ethnic groups. It shows that while children from the dominant white category show clear signs of in-goup bias in their sharing decisions, children from the East Asian minority behave based on a more complex ethnic identity. The third part presents a simple game theoretic model to outline a potential evolutionary origin for a genetic disposition to punish behaviour that conflicts with prevailing moral norms. The model shows how human evolution in small groups can make moral punishment evolutionarily advantageous for individual agents.