Age dissociates recency and lag recency effects in free recall

The temporal relations among word-list items exert a powerful influence on episodic memory retrieval. Two experiments were conducted with younger and older adults in which the age-related recall deficit was examined by using a decomposition method to the serial position curve, partitioning performance into (a) the probability of first recall, illustrating the recency effect, and (b) the conditional response probability, illustrating the lag recency effect (M. W. Howard & M. J. Kahana, 1999). Although the older adults initiated recall in the same manner in both immediate and delayed free recall, temporal proximity of study items (contiguity) exerted a much weaker influence on recall transitions in older adults. This finding suggests that an associative deficit may be an important contributor to older adults' well-known impairment in free recall.     

Using overt rehearsals to explain word frequency effects in free recall

Three experiments examined the word frequency effect in free recall using the overt rehearsal methodology. Experiment 1 showed that lists of exclusively high-frequency (HF) words were better recalled, were rehearsed more, and were rehearsed to more recent serial positions than low-frequency (LF) words. A small HF advantage remained even when these 2 variables were equated. Experiment 2 showed that all these effects were much reduced with mixed lists containing both HF and LF words. Experiment 3 compared pure and mixed lists in a within-subject design and confirmed the findings of Experiments 1 and 2. It is argued that number of rehearsals, recency of rehearsals, and strength of interitem associations cause the word frequency effect in free recall.     

Manipulating the word frequency effect in free recall

A recall advantage for common words was not evidenced when subjects generated or rated the list words on the basis of commonness and on a semantic, phonological, or orthographic basis prior to recall. Recall of the same set of words following only structural judgments of the words resulted in the usual recall advantage for common words. Results were not consistent with interpretations based only on the associative strengths of the recalled items. A process based on categorization of the words to be recalled was suggested as an alternative explanation.     

The effects of interference tasks on recency in the free recall of action events

Summary Lists of verbal instructions were read aloud and each was enacted either by the subject (SPTs) or by the experimenter (EPTs). In Experiment 1 free recall was made of lists of SPTs and EPTs either immediately after presentation, after an empty 20-s delay interval, or after a 20-s delay interval filled with backward counting. The recall of recency items was unaffected by the empty delay interval, but was somewhat reduced by the counting task. In Experiment 2 free recall was made of lists of SPTs and EPTs either immediately after presentation or after a delay that was filled with a single SPT or a single EPT, 20 s in length. The recency effect evident in the immediate-recall condition was virtually wiped out in the delay conditions, irrespective of whether the delay task matched those in the free-recall list or not. These results are discussed in terms of the mnemonic similarity of the two types of action event.     

Primacy and recency effects in immediate free recall of sequences of spatial positions

This study evaluated the serial position curve based on free recall of spatial position sequences. To evaluate the memory processes underlying spatial recall, some manipulations were introduced by varying the length of spatial sequences (Exp. 1) and modifying the presentation rate of individual positions (Exp. 2). A primacy effect emerged for all sequence lengths, while a recency effect was evident only in the longer sequences. Moreover, slowing the presentation rate increased the magnitude of the primacy effect and abolished the recency effect. The main novelty of the present results is represented by the finding that better recall of early items in a sequence of spatial positions does not depend on the task requirement of an ordered recall but it can also be observed in a free recall paradigm.     

Modality dependency of loss of recency in free recall

Summary Four experiments were carried out in which the probability of free recall of words as a function of serial position within lists was examined. The lists were presented either auditorily or visually, with subjects either silent or engaged in irrelevant articulation, and with recall either immediate or after an auditory or visual intervening task. The results provide evidence for the presence of modality-specific capacity limitations in primary memory, and also indicate that forgetting may occur in a last-in, first-out manner.The authors thank Nancy Chenier for assistance with Experiment 4, and two anonymous reviewers for their helpful comments. Research has been supported by the SRC (MM) and MRC (GVJ). Requests for offprints should be sent to Maryanne Martin, University of Oxford, Department of Experimental Psychology, South Parks Road, Oxford OX1 3UD, England.     

Empirical and theoretical limits on lag recency in free recall

One widely accepted empirical regularity in free recall holds that when people successively transition from report of one list item to another, they prefer transitions across short lags (e.g., by reporting items from adjacent serial positions) to transitions involving large lags. This regularity has provided crucial support for the temporal context model (TCM), a model of the evolution of temporal context in episodic memory (Howard & Kahana, 2002a). We report a reanalysis of 14 data sets that shows that, contrary to the presumed preference for short lags, people often produce transitions with larger lags during recall. We show that these data cannot be accommodated by the TCM. We furthermore show that existing applications of the model have, for mathematical convenience, introduced assumptions that have circumvented its core principle of context evolution. When we instantiated the TCM as it was actually described, with a gradually evolving context, we found that its behavior qualitatively departed from that of the version currently implemented, but that the model was still unable to capture the nature of transitions in free recall. We conclude that the TCM requires further modification and development before it can explain the data that constitute its main source of support. Supplementary materials relevant to this article can be downloaded from the Psychonomic Society’s Norms, Stimuli, and Data Archive, www.psychonomic .org/archive.     

The effects of stimulus set size and word frequency on verbal serial recall

Two experiments are reported which examine immediate serial recall for high-and low-frequency words. The words in each list were either repeatedly drawn from the same small pool of candidates (in the closed set conditions) or each word only ever occurred once during the experiment (in the open set conditions). The results consistently show an effect of word frequency but the effect of set size was only apparent for low-frequency words. It is argued that both frequency and set size effects reflect processes concerning the “clean-up” of degraded short-term memory traces.     

The effects of stimulus set size and word frequency on verbal serial recall

Two experiments are reported which examine immediate serial recall for high- and low-frequency words. The words in each list were either repeatedly drawn from the same small pool of candidates (in the closed set conditions) or each word only ever occurred once during the experiment (in the open set conditions). The results consistently show an effect of word frequency but the effect of set size was only apparent for low-frequency words. It is argued that both frequency and set size effects reflect processes concerning the "clean-up" of degraded short-term memory traces.     

Influences of environmental context on the recency effect in free recall

A total of 208 undergraduate participants incidentally encoded a list of seven pairs of familiar words in two experiments. A 30-sec calculation task was imposed before and after each pair was encoded. Participants received a free recall test 24 h (Experiment 1) or 10 min (Experiment 2) after the encoding session, under conditions in which the original environmental context was reinstated or not. The environmental context was manipulated in terms of the combination of the physical features of the room, the subsidiary task conducted, the experimenter (Experiment 1), or background music (Experiment 2). A recency effect appeared when the original environmental context was reinstated in both experiments, even though the IPI/RI ratio was too small to produce recency effects according to the ratio rule. The results imply that the environmental context should be taken into account for the recency effect.     

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

The authors present a new model of free recall on the basis of M. W. Howard and M. J. Kahana's temporal context model and M. Usher and J. L. McClelland's 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 in which an internal contextual state is used as the sole cue for retrieval across time scales.     

Phonological similarity and enhanced auditory recency in longer-term free recall

The effect of phonological similarity amongst list items on the modality effect was investigated in free recall with distraction activity interpolated before and after each list word. In Experiment 1 the distractor activity involved counting backward silently mouthing each number, and the modality effect was drastically attenuated by high similarity. This outcome is comparable with that found in immediate recall, and it is consistent with an echoic memory interpretation. In Experiment 2 the same backward-counting task was performed with each number being vocalized, and the modality effect was unaffected by phonological similarity. This outcome leads to the stronger conclusion that, under those conditions at least, the modality effect cannot be echoic. Implications of these findings for general theoretical accounts of the modality effect are discussed.     

Continued word associations and free recall

Two experiments on the short-term free recall of 12-word associated and non-associated lists are reported. Degree of association (derived from norms obtained by continuous controlled association) and word frequency were varied. Significant facilitation as a result of the associative manipulations was obtained and clustering of the responses was positively related to this. Clustering was also affected by the method of presentation of the associated words; this occurred more often when they were grouped in presentation than when they were presented randomly arranged among other words in the list. Low frequency associated word lists were generally found to be more efficiently recalled than those of comparable association values but consisting of high frequency words.     

Detrimental influence of contextual change on spacing effects in free recall

Two experiments were conducted to determine the mechanism underlying the spacing effect in free-recall tasks. Participants were required to study a list containing once-presented words as well as massed and spaced repetitions. In both experiments, presentation background at repetition was manipulated. The results of Experiment 1 demonstrated that free recall was higher for massed items repeated in a different context than for massed items repeated in the same context, whereas free recall for spaced items was higher when repeated in the same context. Furthermore, a spacing effect was shown for words repeated in the same context, whereas an attenuated spacing effect was revealed for words repeated in a different context. These findings were replicated in Experiment 2 under a different presentation background manipulation. Both experiments seem to be most consistent with a model that combines the contextual variability and the study-phase retrieval mechanism to account for the spacing effect in free-recall tasks.     

Primacy and recency in primed free association and associative cued recall

Two experiments compared the serial positions of primed words in an implicit free association test with words recalled in a cued recall test. In both tests, weakly or strongly related word pairs were studied, and the first words of each pair formed the test cues. In the implicit test, weakly related words pairs showed primacy and extended recency effects but strongly related word pairs did not. In the explicit test, both weakly and strongly related word pairs showed primacy and extended recency effects. These functional dissociations between implicit and explicit memory tests indicate that strongly related word pairs are encoded together because they have unitized memory representations that function as integrated units without requiring any additional associative links to be made, but that an additional system or process is required to strengthen weakly related word pairs during encoding. In addition, a further additional system or process is accessed by explicit retrieval.     

Disentangling the effects of word frequency and contextual diversity on serial recall performance

Research shows that contextual diversity (CD; the number of different contexts in which a word appears within a corpus) constitutes a better predictor of reading performance than word frequency (WF), that it mediates the access to lexical representations, and that controlling for contextual CD abolishes the effect of WF in lexical decision tasks. Despite the theoretical relevance of these findings for the study of serial memory, it is not known how CD might affect serial recall performance. We report the first independent manipulation of CD and WF in a serial recall task. Experiment 1 revealed better performance for low CD and for high WF words independently. Both effects affected omissions and item errors, but contrary to past research, word frequency also affected order errors. These results were confirmed in two more experiments comparing pure and alternating lists of low and high CD (Experiment 2) or WF (Experiment 3). The effect of CD was immune to this manipulation, while that of WF was abolished in alternating lists. Altogether the findings suggest a more difficult episodic retrieval of item information for words of high CD, and a role for both item and order information in the WF effect.     

The interaction of word frequency and concreteness in immediate serial recall

Word frequency and word concreteness are language attributes that have been shown to independently influence the recall of items in verbal short-term memory (STM). It has been argued that such effects are evidence for the action of long-term memory knowledge on STM traces. However, research to date has not investigated whether these variables interact in serial recall. In two experiments, we examined the behavior of these variables under factorial manipulation and demonstrated that the effect of word frequency is dependent on the level of concreteness of items. Serial recall performance is examined with reference to two explanatory approaches: Walker and Hulme’s (1999) dual-redintegration account and language-based models of STM. The data indicate that language-based models are more compatible with the observed effects and challenge the view that frequency and concreteness effects in STM are the products of distinct mechanisms.     

Interitem encoding and directed search in free recall

The paper proposes a cognitive structure consistent with principles of encoding and a rule for its utilization in verbal recall. The encoding and utilization rules lead to phenomena similar to known serial position effects. A detailed analysis of overt rehearsal data and other experimental results are presented in support of the claim that encoding and search mechanisms characterized by these rules could be important factors in serial position effects of verbal recall. Similar rules might be helpful in dealing with other tasks which seem to mirror the utilization of a cognitive structure.