A context-based theory of recency and contiguity in free recall.

Abstract

We present a new model of free recall based on Howard and Kahana's (2002) temporal context model and Usher and McClelland's (2001) leaky-accumulator decision model. In this model, contextual drift gives rise to both short-term and long-term recency effects, and contextual retrieval gives rise to short-term and long-term contiguity effects, Recall decisions are controlled by a race between competitive leaky-accumulators. The model captures the dynamics of immediate, delayed, and continual distractor free recall, demonstrating that dissociations between short-and long-term recency can naturally arise from a model that uses an internal contextual state as the sole cue for retrieval across time scales.The Law of Recency refers to the observation that memories of recent experiences come to mind more easily than memories from the distant past (T. Brown, 1824;Calkins, 1896). Given the ubiquitous nature of recency across time-scales, memory tasks, and stimulus materials, it is not surprising that it has occupied center stage in theoretical analyses of memory over many decades (Crowder, 1976).Whereas some students of memory have sought a common cause for the varied manifestations of recency (Crowder, 1982;Greene, 1986) others have posited distinct mechanisms for the recency effects observed at short and at long time scales (Atkinson & Shiffrin, 1968). In support of a dual-store explanation of recency, Davelaar, Goshen-Gottstein, Ashkeriazi, Haarmann, and Usher (2005) identified several striking differences between the recency effects observed in immediate free recall and continual distractor free recall. In immediate free recall, participants are asked to recall the list items, in any order, immediately following the last item presentation. In continual distractor free recall, participants are given a demanding distractor task following each list item. After the last period of distraction they are asked to recall the items in any order (see Figure 1 for a graphical description of the free recall tasks). Davelaar et al. (2005) suggest that the existence of dissociations between short-and long-term recency calls into question models that hypothesize a general forgetting process underlying recency phenomena observed at different time scales. One popular class of general forgetting models assumes that a time-varying internal context signal gives rise to recency in both shortterm and long-term recall tasks (see Kahana, Howard, & Polyn, 2008, for a review). Davelaar et al. (2005) instead propose a model of free recall in which an activation-based short-term store (STS) produces recency in immediate free recall, and a time-varying context signal Correspondence concerning this article may be addressed to Per B. Sederberg (persed@princeton.edu). NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript produces long-term recency via a weight-based long-term store (LTS) in continual distractor free recall.We next review some of the major empirical phenomena observed in free recall and t...

Beginning at the beginning: Recall order and the number of words to be recalled.

“…Our interpretation of our data may go some way towards overcoming the difficulties that unitary accounts of IFR (e.g., Brown et al, 2007; Howard & Kahana, 2002;Polyn, et al, 2009;Sederberg, et al, 2008;Tan & Ward, 2000) have in explaining the IFR of short lists.…”

“…Retrieval is often assumed to be both self-propagating and self-limiting (e.g., Roediger, 1973Roediger, , 1974, such that the recall of one list item can facilitate the recall of the next (e.g., Howard & Kahana, 1999; Kahana, 1996; Nairne, Ceo & Reysen, 2007; see also Lohnas & Kahana, 2014), but can also cause output interference (e.g., Beaman, 2002; Bunting, Cowan & Saults, 2006, Cowan, Saults, Elliott & Moreno, 2002 Nairne et al, 2007;Oberauer, 2003;Tan & Ward, 2007). It may be that the "ISR-like" recall of short lists is an effective strategy to recall many of the words from short lists, but that when only one or two responses are required, participants favor the greater certainty of accessing only the most recent items.Our interpretation of our data may go some way towards overcoming the difficulties that unitary accounts of IFR (e.g., Brown et al, 2007; Howard & Kahana, 2002;Polyn, et al, 2009;Sederberg, et al, 2008;Tan & Ward, 2000) have in explaining the IFR of short lists.Unitary accounts of IFR tend to predict extended recency effects, and so to date they have been found wanting in explaining participants' tendencies to initiate the recall of short lists with the first list item and to continue to recall in an "ISR-like" manner. However, our data suggest that, even in the IFR of very short lists, participants prefer to initiate recall with one of the last list items if they only have to recall one or two list items.…”

“…The privileged access to the recency items may reflect the output of a short-term store in dual store accounts of IFR (Anderson, et al, 1998;Davelaar et al, 2005;Raaijmakers & Shiffrin, 1981), or be the result of greater temporal distinctiveness (Brown et al, 2007) or a greater match with the end-of-list context (Howard & Kahana, 2002;Polyn, et al, 2009;Sederberg, et al, 2008;Tan & Ward, 2000) in unitary accounts of IFR.…”

“…Similarly, accounts that assume that items are associated with a drifting or changing temporal context (e.g., Howard & Kahana, 2002;Polyn, Norman & Kahana, 2009;Sederberg, Howard & Kahana, 2008;Tan & Ward, 2000) propose that more recent items should be generally more readily accessible than earlier list items, because they share contexts that are more closely related to the test context. The finding that it is the first item (and not the last item) that is most accessible when recalling short lists creates a distinct deviation from the predictions of these unitary accounts.…”

A Dynamic Approach to Recognition Memory

“…The simplified cued recall model we proposed to explain source memory judgments was, in turn, based on a samplingand-recovery model of recall (Raaijmakers & Shiffrin, 1981;Diller et al, 2001) that was itself motivated by the dynamics of inter-retrieval times and stopping times. The temporal context model (Howard & Kahana, 2002) has also been extended to account for the dynamics of recall using a competing accumulator approach similar to the one we have used to explain recognition (Sederberg, Howard, & Kahana, 2008;Polyn, Norman, & Kahana, 2009). These extensions revealed, among other things, the importance of semantic associations between successively recalled items predicting inter-response latencies, which would not necessarily have been apparent otherwise.…”