Source Discrimination for Unrecognized Items? On Empirical Arguments Against the High-Threshold Model of Source Memory

Recently, Starns et al. (2008) collected source judgments for old items, which participants had claimed to be new, and found residual source discriminability depending on the old-new response bias. The finding was interpreted as evidence in favor of the multivariate signal-detection model but against the high-threshold model of source memory. According to the latter, “new” responses only follow from the state of old-new uncertainty for which no source discrimination is possible, and the probability of entering this state is independent from the old-new bias. However, when unrecognized items were presented for source discrimination, Starns et al.’s participants knew that the items had been studied. To test whether this implicit feedback leads to further retrieval attempts and thus to source memory of presumably unrecognized items, we compared Starns et al.’s task to tasks without implicit feedback. Our results challenge the original finding and lend support to discrete processing in source memory.