The directed forgetting effect proposes that serious effort to forget obtained information should lead to worse memory results than if this effort is not made. The paper by Sahakyan, Delaney and Waldum (2008) "evaluated whether the magnitude of the list-method directed forgetting effect is strength dependent." (p.408). The authors manipulated the item strength within 3 independent studies through depth of processing, processing time and the context strength. The replication will focus on the third study of the paper manipulating the context strength. Context strength "(...) is varied by spacing repetition. Weak items were repeated twice consecutively (massed presentation), while strong items were repeated twice but several other words in between the two repetitions (spaced presentation).” (p.411) The target effect for the replication is the interaction effect between context strength and condition (directed forgetting vs. control). If spaced presentation will lead to significant stronger forgetting effects than massed presentation, this would be empirical support for one prominent hypothesis, "(...) that directed forgetting is a context effect." (p. 408).
Summary of Replication Attempt
In the replication at hand we evaluated the magnitude of the direct forgetting effect of weak (massed) and strong (spaced) items. We failed to replicate the previous finding by Sahakyan et al. (2008), but the descriptive effect goes into the same direction (see figure 1). A possible explanation for this result could be the non-significant main effect of the forgetting manipulation (partial η2 Sahakyan et al. (2008) = .09; partial η2 replication = .024), which is a necessary pre-condition for investigating the interaction effect.
See 'Files' for the report.