Making Decision in Estimating Pheromone by an Ant itself, Expressed as a Cause-Effect Loop

Social insects ants secrete something like pheromone or wax by which an individual can identify their trail. The ants Lasius niger L. show this behavior but sometimes change trails in branched maze experiments. An individual ant can estimate the reliance of its recruitment trail. The estimation is measured by post-information, i.e. by the frequency of turning back on a recruitment trail. The relationship between the post-information rate and the probability of choosing between alternative routes is analyzed. It turns out that (1) a momentary burst of post-information can trigger the retreat of an existing recruitment trail; (2) post-information rate is correlated with pheromone concentration. Post-information sometimes implies the occurrence of an internal decision making, but at other times is a response to pheromone. Due to this cause-effect loop, a straight relation between post-information and pheromone concentration is not observable. Alternate shifting between positive and negative correlation can however be detected. From the precise analysis, it is shown that this cause-effect loop can be used as a model of ant's own decision making. It turns out to be a model of system generating hierarchical structure.