ABSTRACT
Things take time. An effective cognitive system requires the ability to perpetuate process sufficiently to match the demands of goal and environment. Some functions, such as the retention of a fact once learned, are subjectively effortless and have a time course of years. For others, such as the serial addition of auditory digits presented every two seconds, continuation over very brief periods feels highly effortful and leads to increasingly error-prone performance (Gronwall & Sampson, 1974).
