ABSTRACT
We live in an uncertain world, and hence – in the view of many scientists – we were designed (by natural selection) to make judgements and decisions under uncertainty. Since all our ancestors had to deal with uncertainty and variability in their environments, it seems inevitable that the mechanisms underlying our cognitive processes have developed means of dealing with this. Of course, animals live an uncertain world also, and it is greatly to their advantage to be responsive to both the absolute and the relative frequencies of events that they experience. For example, if a bear likes to eat berries from a certain kind of bush, it is in its interest to be able to learn that these bushes grow more often in one kind of landscape than another or that they are often found in proximity to another (perhaps inedible) plant. A bear that learns to use such cues in order to find food is acting as if it were calculating and responding to conditional probabilities.
