A note on the stop-signal paradigm, or how to observe the unobservable.

A new theoretical analysis of the stop-signal paradigm is proposed. With the concepts of crude and net hazard functions, the nonobservable control-latency distribution can be estimated from observ-able reaction times. This result allows a test of Logan & Cowan's (1984) model without any simplify-ing assumptions. In studies using response time as the major dependent vari-able, the stop-signal procedure has been used by several investi-gators in an attempt to reveal the time course of hypothesized underlying sensory or cognitive processes or both (e.g., Lappin &Eriksen, 1966; Oilman, 1973). In this paradigm, subjects are given a primary reaction time task to perform, and a stop signal that tells subjects to withhold their responses is sometimes pre-sented shortly after the primary stimulus. Logan and Cowan (1984) presented a theory of inhibition of thought and action that focuses on this paradigm. The purpose of this note is to present a new theoretical analysis of the stop-signal paradigm