ABSTRACT
This paper deals with the interplay between structural and functional factors in the reaction process. First some research on Sternberg’s idea of processing stages is reviewed. The conclusion is that the results of most studies can be satisfactorily described as a simple sequence of three processing stages. However, it is difficult to incorporate the observed interactions between auditory signal intensity and time uncertainty, and between S—R compatibility (in tactual choice reactions) and time uncertainty. A variable criterion model can handle these exceptions but, in its turn, cannot easily account for several results — like additivity between visual signal intensity and time uncertainty — that fit the processing stages model. It is proposed that intense signals, that is, tactual signals and loud auditory signals, produce an orienting response, which may be labeled as immediate arousal. The effect of immediate arousal is to enhance readiness to respond. When the response made requires a choice the effects of immediate arousal are inhibited. Several implications of this view are discussed.
