What, therefore, is the explanatory role of the "stimulus" in the reaction time situation? As a matter of fact, the situation is quite the opposite of what it is thought to be in a superficial stimulus-response way of thinking. The reaction of the subject does not appear because a stimulus is presented, but the stimulus itself is a result of the action of the subject, and it is possible only therefore that the subject is organized to act in a certain way. The stimulus exists as a stimulus because a preorganized system defining some environmental change as a stimulus is present before this change appears. When the stimulus is finally presented it does not cause any "processing" because this "processing" has been carried out before its appearance, in the sense that the organism must have a system into which this environmental change defined by the experimenter fits. The subject is not "reacting" to the stimulus, but the behavior of the subject defines the changes in the environment which may act as "stimuli" and are needed as a part of the organization necessary for the achievement of the desired results. (Järvilehto,1998, p. 331).Let us say that the stimulus occurs at time t0. Then, we can agree with Järvilehto that the stimulus in a reaction time experiment is a result of the action of the subject prior to t0. And we can agree with much else in this. Only, why would the fact that the stimulus at t0 is the product of prior actions and features of the preorganized system show that the system is not reacting to the stimulus after t0? Why can't it be that actions of the system prior t0 lead to the stimulus at t0, but then the stimulus at t0 leads to a later response at, say, t1?
Järvilehto, T. (1998). The theory of the organism-environment system: I. Description of the theory. Integrative Psychological and Behavioral Science, 33(4), 321-334.