Measuring channel dependence in separate activation models

Abstract

In the bimodal detection task, the observer must respond as soon as a signal is presented in either of two modalities (e.g., a tone or a flash). A typical finding is a facilitation of reaction time for redundant-signal trials, that is, when both signals are presented simultaneously. Separate-activation models assume that the two signals are processed simultaneously within different channels and that a response is initiated as soon as an activation level is exceeded in either channel. This paper examines a number of approaches to formulating a model of the stochastic mechanisms involved. Conditions allowing inference of the correlational structure of the channel processes are discussed, and new models are proposed. Moreover, distribution inequalities for testing of the models under weakened independence assumptions are derived. © 1986 Psychonomic Society, Inc.