When does semantic similarity help episodic retrieval?

Free recall illustrates the spontaneous organization of memory. This organization comes in two forms, the temporal organization of the list and the semantic relations among list items. Using estimates of semantic Similarity provided by latent semantic analysis (LSAT Landauer & Dumais, 1997), we simultaneously assessed the effects of temporal and semantic proximity on output order in delayed and continuous-distractor free recall of random word lists. These analyses revealed that subtle variations in semantic similarity have large effects on recall transitions in delayed free recall. Further, these effects decrease as the duration of the interitem distractor (IPI) was increased from 2-16 s. In contrast, the effect of temporal proximity on recall transitions did not change with increasing IPI. This dissociation in the effects of interitem distraction on semantic and temporal similarity effects presents a new challenge for models of free recall and episodic memory retrieval. (C) 2002 Elsevier Science.