Emergent Collective Decisions through Self-Organisation

Decision making mechanisms are important features for an intelligent agent, as they make it possible to display different behaviours as a function of the particular environmental situation the agent perceives and in relation to its beliefs and its desires. Individually, a decision is often the result of a process that takes into account information gathered from the environment. For example, animals collect information about the quality of a food source while foraging. Depending on this information, they base their decision to stay in the same area or to search for a more profitable one. We will come back on these issues in Chapter 10.

A more complex case is presented by decisions that have to be taken at a collective level. Societies may entrust their decision making ability to a few leaders that care about the whole community. This is the case of groups of mammals, often characterised by the presence of a few individuals that lead the activities of the others. The situation is different in insect societies, in which decisions are taken collectively. Many examples of collective choice have been studied so far in social insects. These decisions are generally the result of a self-organising process: the decision emerges from the numerous interactions among the individuals forming the colony, and from the interactions between individuals and the environment (Camazine et al., 2001). Therefore, complex decision making processes can be observed at the collective level, notwithstanding the simple behavioural rules followed by each individual insect. Examples of such processes can be found in honey bees that collectively select the most profitable foraging site between two different food sources (Seeley, 1995), or in ants that collectively choose the shortest path from the nest to a food source (Beckers et al., 1993).