SIAM-AMS Proceedings Volume 13 1981
1. Introduction. The use of reaction time (RT) measurement in the study of cognitive processes is one of the oldest ideas in experimental psychology, but still one of the most active ones in the field of human information processing of today. It is essentially due to the Dutch physiologist F. C. Donders [ 1969]. He advanced the assumption that cognitive processes proceed in stages or serially, and proposed to measure the duration of a cognitive process by comparing the average RT's from a task which does and another one which does not require the execution of that process for the solution of the task.
Much of the current popularity of the RT method and also of its theoretical foundations is due to the work of S. Sternberg [ 1966], [ 1969], [ 1975]. As an example, let us consider Sternberg [ 1966] memory scanning experiment which has since become a classic in the field. In the experiment, he studied how long it takes us to scan the contents of short-term memory.
On a given trial of the experiment, the subject was to memorize a short list of digits which were displayed sequentially. After a brief delay, a test digit was shown, and the subject was to decide as fast as possible whether the digit was one of the digits in memory. For example, the memory list might be (3, 1, 5, 7, 4). On a positive test trial, the test digit '7' might be shown; on a negative test trial, '8' might be shown as test digit. The subject indicated his decision (yes' or 'no') by operating one of two response levers. RT was defined as the time from the onset of the test digit to the occurrence of the response. The focus of interest was whether and how RT is influenced by the number of items
© 1981 American Mathematical Society____________________
This work was done during my sabbatical year at the Human Information-Processing Research Department, Bell Laboratories, Murray Hill, N. J. I am grateful to the Bell Labs and Saul Sternberg for the hospitality, and to him, Jan van Santen, and Dave Noreen for many helpful discussions. Thanks are due to Wolfgang Hell for a critical reading of the manuscript.