The nonspecific preparation that follows a warning stimulus (WS) to speed responding to an impending imperative stimulus (IS) is generally viewed as a strategic, intentional process. An alternative view holds that WS acts as a conditioned stimulus that unintentionally elicits a tendency to respond at the moment of IS presentation as a result of a process of trace conditioning. These views were contrasted as explanatory frameworks for classical effects on reaction time of the duration and intertrial variability of the foreperiod, the interval between WS and IS. It is shown that the conditioning view accounts for the available data at least as well as the strategic view. In addition, the results of 3 experiments provide support for the conditioning view by showing that unintentional contributions to nonspecific preparation can be dissociated from intentional contributions.

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The hazard function describes the conditional probability that an event will occur at a given moment, given that it has not yet occurred. In warned reaction time tasks, it is a classical finding that the response to a target stimulus is faster as its hazard is higher, which has led to the widespread belief that hazard somehow drives temporal preparation. Alternatively, recent cognitive theories propose that temporal preparation is driven by memory traces of earlier timing experiences. To distinguish between these views, we presented different groups of participants with different distributions of foreperiods between temporal cues and target stimuli. Three experiments revealed clear transfer effects of this manipulation in a test phase where all participants received, after explicit instruction, the same uniform distribution. These findings demonstrate that temporal preparation is driven by past experience, not by current hazard. (PsycINFO Database Record

We outline a new multiple trace theory of temporal preparation (MTP), which accounts for behavior in reaction time (RT) tasks in which the participant is presented with a warning stimulus (S1) followed by a target stimulus (S2) that requires a speeded response. The theory assumes that during the foreperiod (FP; the S1–S2 interval) inhibition is applied to prevent premature response, while a wave of activation occurs upon the presentation of S2. On each trial, these actions are stored in a separate memory trace, which, jointly with earlier formed memory traces, starts contributing to preparation on subsequent trials. We show that MTP accounts for classic effects in temporal preparation, including mean RT–FP functions observed under a variety of FP distributions and asymmetric sequential effects. We discuss the advantages of MTP over other accounts of these effects (trace-conditioning and hazard-based explanations) and suggest a critical experiment to empirically distinguish among them.

The authors hypothesized that there are distinct intentional and unintentional influences on nonspecific preparation for a future event. In 2 experiments, participants responded to an imperative stimulus (S 2 ) that was presented equiprobably either 400 ms or 1,200 ms after the offset of a warning stimulus (S 1 ). During the S 1 -S 2 interval, the authors measured the contingent negative variation (CNV), an event-related brain potential reflecting nonspecific preparation. S 1 provided either no information or reliable information about the duration of the impending S 1 -S 2 interval, thereby allowing an intentional influence on the state of preparation. The effect of S 1 information on the CNV was approximately additive to the effect of the S 1 -S 2 interval that was used on the preceding trial. This supports the view that the preceding S 1 -S 2 interval contributes unintentionally to the state of nonspecific preparation guided by a process of trace conditioning.