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This article presents four experiments that tested predictions of SOB (Serial Order in a Box), an interference-based theory of short-term memory. Central to SOB is the concept of novelty-sensitive encoding, which holds that items are encoded to the extent that they differ from already-encoded information. On the additional assumption that distractors are encoded into memory in the same manner as list items, the theory predicts differential effects of interfering activity based on the similarity structure of distractors. Consistent with predictions, three experiments showed that overt articulation of distractors in between recalls of list items did not affect forgetting when the same distractor was repeated multiple times, whereas forgetting was observed if several different distractors were articulated within the same time span. A fourth experiment showed that the absence of forgetting with repeated articulations of the same item was not due to compensatory attentional refreshing of memory traces. The data support the notion that forgetting from short-term memory arises from interference and are difficult to reconcile with temporal decay. (Contains 8 figures and 3 tables.)

According to temporal distinctiveness models, items that are temporally isolated from their neighbors during list presentation are more distinct and thus should be recalled better. Contrary to that expectation of distinctiveness views, much recent evidence has shown that forward short-term serial recall is unaffected by temporal isolation. We report two experiments using reconstruction of order tasks that confirmed that when report order is strictly forward, temporal isolation does not benefit performance. However, both experiments also showed that when report order is unconstrained, temporal isolation does benefit performance. The differences between forward and unconstrained report were found to be independent of whether or not people can anticipate the type of test at encoding. The presence and absence of isolation effects under two different conditions, both requiring memory for order, challenges many existing theories of memory but is compatible with the idea that multiple differentially weighted types of information contribute to memory retrieval.

In short-term serial recall, similar-sounding items are remembered more poorly than items that do not sound alike. When lists mix similar and dissimilar items, performance on the dissimilar items is of considerable theoretical interest. Farrell and Lewandowsky [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.] recently showed that if guessing strategies are controlled, dissimilar items on mixed lists are recalled more accurately than on pure dissimilar lists, a finding that challenges several current theories of serial recall. This article presents two experiments that extend the generality of the mixed-list advantage for dissimilar items and then applies three theories of memory--the primacy model, SIMPLE, and SOB--to the data. The simulations show that the data are best explained by the SOB theory [Farrell, S. (2006). Mixed-list phonological similarity effects in delayed serial recall. "Journal of Memory and Language," 55, 587-600; Farrell, S., & Lewandowsky, S. (2002). An endogenous distributed model of ordering in serial recall. "Psychonomic Bulletin & Review," 9, 59-79.] which, unlike most other current theories, posits that similarity has an effect at the time of encoding.

According to temporal distinctiveness models, items that are temporally isolated from their neighbors during list presentation are more distinct and thus should be recalled better. Event-based theories, by contrast, deny that time plays a role at encoding and predict no beneficial effect of temporal isolation, although they acknowledge that a pause after item presentation may afford extra opportunity for a consolidation process such as rehearsal or grouping. We report two experiments aimed at differentiating between the two classes of theories. The results show that neither serial recall nor probed recall benefit from temporal isolation, unless participants use pauses to group a list. Simulations of the SIMPLE model provide convergent evidence that short-term memory for serial order need not involve temporal representations.

Several competing theories of short-term memory can explain serial recall performance at a quantitative level. However, most theories to date have not been applied to the accompanying pattern of response latencies, thus ignoring a rich and highly diagnostic aspect of performance. This article explores and tests the error latency predictions of four alternative mechanisms for the representation of serial order. Data from three experiments show that latency is a negative function of transposition displacement, such that list items that are reported too soon (ahead of their correct serial position) are recalled more slowly than items that are reported too late. We show by simulation that these data rule out three of the four representational mechanisms. The data support the notion that serial order is represented by a primacy gradient that is accompanied by suppression of recalled items.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jml.2006.08.006 Byline: Stephan Lewandowsky (a), Evan Heit (b) Abstract: This introductory article to the Journal of Memory and Language special issue on memory models discusses the progress made in the field of memory modeling during the last few decades in terms of a number of previously suggested criteria, using the articles in this issue as examples. There has been considerable progress, both at a technical level (e.g., concerning model comparison and model analysis techniques) and at a psychological level (as evidenced by the increasingly tight interplay between theory and data on human memory). The article concludes by proposing a few generic targets for future modeling work. Author Affiliation: (a) School of Psychology, University of Western Australia, 35 Stirling Highway, Mail Bag M304, Crawley, W.A. 6009, Australia (b) University of California, Merced, USA Article History: Received 9 August 2006 Article Note: (footnote) [star] The authors are grateful to Kay Bock, Bob Greene, and Dave Plaut for comments on this article. Preparation of this article was facilitated by a Large Grant and by a Discovery Grant from the Australian Research Council to the first author.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jml.2005.08.004 Byline: Stephan Lewandowsky (a), Gordon D.A. Brown (b), Tarryn Wright (a), Lisa M. Nimmo (a) Keywords: Short-term memory; Serial recall; Time and memory; Computational modeling Abstract: According to temporal distinctiveness models, items that are temporally isolated from their neighbors during list presentation are more distinct and thus should be recalled better. Event-based theories, by contrast, deny that time plays a role at encoding and predict no beneficial effect of temporal isolation, although they acknowledge that a pause after item presentation may afford extra opportunity for a consolidation process such as rehearsal or grouping. We report two experiments aimed at differentiating between the two classes of theories. The results show that neither serial recall nor probed recall benefit from temporal isolation, unless participants use pauses to group a list. Simulations of the SIMPLE model provide convergent evidence that short-term memory for serial order need not involve temporal representations. Author Affiliation: (a) University of Western Australia, Australia (b) University of Warwick and University of Western Australia, Australia Article History: Received 21 December 2004; Revised 8 August 2005 Article Note: (footnote) [star] Preparation of this paper was facilitated by a Large Grant and by a Discovery Grant from the Australian Research Council to the first author, and by a Linkage International Grant from the Australian Research Council to the first and second author. We gratefully acknowledge assistance from Leo Roberts at all stages of manuscript preparation and Daniel Little for assistance during data collection.