Mixed-list phonological similarity effects in delayed serial recall

Recent experiments have shown that placing dissimilar items on lists of phonologically similar items enhances accuracy of ordered recall of the dissimilar items [Farrell, S., & Lewandowsky, S. (2003). Dissimilar items benefit from phonological similarity in serial recall. Journal of Experimental Psychology: Learning, Memory, and Cognition, 29, 838-849.]. Two explanations have been offered for this effect: an encoding explanation, in which items similar to current memory contents are given less encoding weight and offer less competition for recall; and a retrieval explanation, which suggests that the long-term similarity structure of the items leads to dissimilar items being more distinct on mixed lists. These theories are compared in an experiment in which a filled delay was introduced between study and test. Simulations show the prominent enhancing effects of similarity after a delay are captured by a model that assumes encoding is sensitive to the similarity of items to other list items [Farrell, S., & Lewandowsky, S. (2002). An endogenous distributed model of ordering in serial recall. Psychonomic Bulletin & Review, 9, 59-79.], but are not handled by a retrieval model [the Start-End Model; Henson, R. N. A. (1998). Short-term memory for serial order: the Start-End Model. Cognitive Psychology, 36, 73-137. ].