Interference in episodic memory: retrieval-induced forgetting of unknown words.

We investigated the dependence of retrieval-induced forgetting of verbal material from influences of word representations in semantic memory. Participants learned novel words, that is, letter strings that were non-words. These items were grouped into different artificial categories during learning. Subsequently, participants retrieval-practiced subsets of items from a part of the categories. This selective retrieval enhanced the recall of practiced items in a final memory test, but impaired memory for non-retrieved items belonging to the same categories. Retrieval-induced forgetting occurred with regard to the number of recalled items, as well as with regard to response times. The results show that episodic associations suffice for selective retrieval of verbal material to entail retrieval-induced forgetting independent of association strength between items and categories in semantic memory. The relevance of this finding for the postulate of interference dependence within the inhibitory account of retrieval-induced forgetting is discussed.