A model using discrete processing requires that information is passed from one stage to another only after the processing in the first stage is complete. Therefore, the processing time required in a discrete model is additive and equal to the sum of the time taken at each level of processing.
The advantage of this type of model is that it provides a convienent method of understanding the effects of different variables on the performance of a given task.
Blackwell's Dictionary of Cognitive Science
Contributed by Valerie Trifts