The Size of The Fan Effect:
Process not Representation

Abstract

The size of fan effects is determined by processes at retrieval, not by whether or not information is represented as situations. Evidence contradicts Radvansky's (in press) claim that time to retrieve information from a situation does not depend on number of elements in a situation. Moreover, Radvansky's principles for ascribing situational models to experiments appear to be post hoc ways of redescribing the data. On the other hand, the evidence does support the ACT-R assumption that participants can adjust their attentional weightings and so produce differential fan effects. Moreover, the ACT-R theory of the fan effect is consistent with many other findings.

In our original paper we tried to show that the retrieval processes in ACT-R provide a successful account for a wide range of phenomena surrounding the fan effect. One of these phenomena was the variation in the size of the fan effect for various concepts across experiments. Here we used some of Radvansky's data which document the variation that can occur in the size of fan effects. Radvansky (in press) challenges our claim to have plausibly accounted for the impressive amount of data he has amassed and instead argues that they can be better accounted for by situation models. In this paper we will argue that ACT-R provides both a more precise and a more plausible theory.

Like Radvansky, we believe that participants frequently set up rich representations of situations (e.g., Anderson & Reder, 1979). The issue is not between situational representations and ACT-R representations. As Radvansky notes in his paper, ACT-R chunks could quite easily implement situational representations. The issue concerns the retrieval processes that operate on the representations, situational or otherwise. We do not think the data support the retrieval process that Radvansky proposes and associates with situational representations. Rather, we think itThe data supports the retrieval process in ACT-R. The ACT-R retrieval process could easily apply to situational representations although we do not think that participants in Radvansky's experiments are creating the situational representations that he ascribes to them. In any case, the ACT-R retrieval model is neutral on this representational issue and does not, as Radvansky claims, "reduce the experimental situation to a paired-associate learning task." We next discuss the ACT-R retrieval assumptions and then Radvansky's assumptions.

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