A Behavioral Theory of Timing

We base a theory of timing on the observation that signals of reinforcement elicit adjunctive behaviors. The transitions between these behaviors are well described as a Poisson process, with a rate constant proportional to the rate of reinforcement in the experimental context. These behaviors may come to serve as the basis for conditional discriminations of the passage of time. Varying the rate of reinforcement will generate distributions of behavior whose mean and standard deviation vary proportionately. Holding the rate of reinforcement constant while manipulating the intervals to be judged will generate different functional relations between the mean and standard deviation, and these will lead to bisection at or slightly above the geometric mean, depending on the measure of bisection employed. The correlation between the rate of the Poisson process and the rate of reinforcement implies that psychometric functions should be affected by the rate of reinforcement. This prediction is confirmed. We extend the models derived from this theory to other phenomena, such as temporal generalization and discrimination, subjective shortening, and paired comparisons of intervals. Current models of choice between delayed reinforcers are consistent with our theory of timing.