Abstract
Research on the role of time in associative learning has changed our understanding of what an association is. It is a measurable fact about the distribution of events in time, not an altered activation-conducting connection in a mind, brain or net. Associative learning is the process of perceiving temporal associations and deciding to act on them. Informativeness- the ratio of a conditional rate to an unconditional rate-is the essential empirical variable, not the probability of reinforcement. The communicated information between temporally associated behavioral and reinforcing events is the log of informativeness. Because the time units in the rate estimates cancel, associative-learning is time-scale invariant: Perceivably associated events may be arbitrarily widely separated. There are no windows of associability nor decaying eligibility traces. The learning rate-operationally defined as the reciprocal of reinforcements prior to the appearance of a conditioned response-is an almost scalar function of relative temporal separation, as measured by informativeness. The central role of informativeness unites our understanding of Pavlovian and operant/instrumental phenomena, revealing unexpected quantitative and conceptual communalities.