1 Modelling Human Behaviour in Agent-Based Models William G. Kennedy, PhD, Captain, USN (Ret.) Krasnow Institute for Advanced Study George Mason University, USA Abstract The modelling of human behaviour is not at all obvious. First, humans are not random. Second, humans are diverse in their knowledge and abilities. Third, besides being controlled by rational decision‐making, human behaviour is also emotional. This chapter attempts to present principles driving human behaviour and reviews current approaches to modelling human behaviour. Key words: human behaviour, cognition, cognitive modelling, decision‐making The behaviour of humans as individuals, in small groups, and in societies is the subject of several fields of research because it has such an important role many aspects of daily life. However, incorporating human behaviour into Agent‐Based Models (ABMs) is a real challenge. It is a challenge primarily because of the short history of our scientific observation of human behaviour, but there is hope. This chapter discusses the challenges of modelling human behaviour, presents and critiques the major approaches available, and some basic principles of human behaviour before providing information on how to integrate human behaviour into agent‐based models. The chapter starts with how not to model human behaviour. How not to model human behaviour To start, humans are not random. They (we) are strange and wonderful. Their behavior may be unexpected or inconsistent (i.e., noisy), but it is not random. As an example, here is a simple demonstration. An easy question will be presented below and you may take hundreds of milliseconds to answer, but do answer. The question is: “Pick a number between one and four.” Have an answer? The most common response is “three” and there is a secondary effect of this task: people feel a need to explain why they chose whatever answer they did. The second most common answer is “two”. Very few people decide to respond with either “one” or “four”. Sadly, there is not a serious study of this behaviour but undocumented sources suggest that the response statistics are close to 50 percent for “three”, 30 percent for “two” and about 10 percent for the other two answers. The common explanation for the selection of “three” is that it was the most “interesting” number in the range. There is also a small number of people who are Kennedy, W.G. (2011) Modelling Human Behavior in Agent-Based Models. Agent-Based Models of Geographical Systems, Part 2, pp 167-179. M. Batty, A. Heppenstall, and A. Crooks (Eds.) Springer.