Wagner ( 1981) has offered a formal model of Pavlovian conditioning in which the notion of rehearsal assumes a central role. According to Wagner, a representation may be said to be in rehearsal in short-term memory when that representation is highly active. It, would thus appear that for Wagner rehearsal is more appropriately characterized as a state of activation than as a process responsible for, or necessary to, a state of high activation. For present purposes, however, whether rehearsal is conceptualized better as a state or as a process is not a central concern. Rather, what is important in the present context is a delineation of the properties or characteristics ascribed to rehearsal by Wagner.
Perhaps the most fundamental property of rehearsal involves an influence on the formation of permanent memories. Specifically, Wagner suggests that post-trial rehearsal is necessary to associative learning. Given the typical Pavlovian conditioning preparation in which a conditioned stimulus (CS) is followed shortly by an unconditioned stimulus (US), the amount learned about the CS-US relation on any particular trial is directly proportional to the length of time during which the representations, of the CS and US are conjointly in rehearsal in short-term memory. Because of the dependence of associative learning on this type of rehearsal, it is appropriate to refer to rehearsal in Wagner's sense as "associative rehearsal."
Wagner identifies two further properties of associative rehearsal important to the present treatment. First, he refers to rehearsal as a "standard operating procedure," by which he emphasizes the notion that rehearsal is an inherent property of the information processing system. That is, the provocation of rehearsal is held to be determined solely by invariant operating characteristics of the information processing system. The second property, which may be viewed as a corollary of the first, is that once initiated, associative rehearsal proceeds mechanically, and thus independently of voluntary control.
The sense of these latter two properties may be captured by referring to associative rehearsal as an automatic, rather than controlled, process. Caution must be exercised, however, in that associative rehearsal in Wagner's scheme does not share all of the characteristics identified 'as those of automatic processes by Shiffrin and Schneider ( 1977). One' of the more obvious discrepancies concerns the relationship between automatic information processing and attentional demands. Shiffrin and Schneider suggest that automatic processing proceeds without attention and thereby does not tax the limited processing capacity of short-term memory. In contrast, Wagner holds that associative rehearsal does I engage or occupy processing capacity (in fact, this proposition formed the basis for one of the earlier studies designed to implicate the operation of rehearsal in associative learning, see Wagner, Rudy, & Whitlow, 1973). However, if the caveat is kept in mind, it may be useful to refer to associative rehearsal as an automatic process in that such reference emphasizes the mechanical, invariant features of this type of rehearsal.