The Logic of Adaptive Behavior

Introduction D ECISION MAKING IS A VERY CHALLENGING PROBLEM, both in human thinking as in artificial intelligence systems. While you are reading this text, many things take place inside your brain. For one thing, you are trying to stay focused on reading this, you are trying to keep yourself nourished, you are trying to remember to send this very important e-mail, and so on. Furthermore, you know how to ride a bicycle, you know how to make coffee and you may know how to write a report using L A T E X, and many more such things. And, additionally, you may have knowledge about Bayesian networks, your left ear, table spoons and possibly even about ninja swords. How on earth can you possibly decide on your next action? Apparently, humans have the ability to store many types of knowledge, operational skills, and do many types of reasoning processes, all at the same time. A complete explanation of this phenomenon, and a working computer-based implementation of such processes, counts as the Holy Grail of the field of artificial intelligence. Therefore, let us first take a look at the significantly more restricted setting of decision making in Figure 1.1. These examples were described by Tversky and Kahneman (1981), who experimented with variants of essentially the same decision problem and investigated the influence of how people interpret the problem on their decisions. The variance in the answer distribution in the two problems is explained by the authors as " The majority choice in this problem is risk averse: the prospect of certainly saving 200 lives is more attractive than a risky prospect of equal expected value, that is, a one-in-three chance of saving 600 lives. [...] The majority choice in problem 2 is risk taking: the certain death of 400 people is less acceptable than the two-in-three chance that 600 will die. The preferences in problems 1 and 2 illustrate a common pattern: choices involving gains are often risk averse and choices involving losses are often risk taking. However, it is easy to see that the two problems are effectively identical. " Interestingly, for humans it seems to matter how a particular problem is represented. Both problems pose the same dilemma, but trigger different responses, due to a concept called decision frame that refers to the decision-maker's conception of the acts, outcomes, and contingencies associated with a particular choice. From this example, …