Research Strategy in the Study of Memory: Fads, Fallacies, and the Search for the "Coordinates of Truth"

The role of variable retrieval in effective learning

Current research on memory indicates that learning is most effective when it involves spaced retrieval practice of study materials. Here, we investigated whether the benefits of both retrieval practice and spacing can be further boosted when variability is introduced across practice sessions. Across six experiments, participants learned translations of foreign vocabulary, with foreign words embedded in contextual sentences hinting at the meaning of these words. These sentences were then either kept constant or varied from one learning cycle to another. Whenever repeated practice took the form of retrieval from long-term memory with contextual sentences serving as cues (with or without feedback after retrieval attempts), variable sentences led to better learning of the meanings of the embedded foreign words than constant sentences. The benefits of variable retrieval were observed both immediately after study and after a 24-h delay, and they were larger when retrieval practice was spaced rather than massed. However, these benefits were not appreciated by the learners who judged learning to be more effective with constant rather than variable cues. This metacognitive illusion, misaligning the effectiveness of learning and its appraisal by learners, was confirmed in the seventh experiment which focused on learning lecture content. Thus, while spaced retrieval practice employing variable cues clearly produces robust benefits for memory performance, such benefits may be severely underappreciated by the learners.

Towards an ecologically valid naturalistic cognitive neuroscience of memory and event cognition

The landscape of human memory and event cognition research has witnessed a transformative journey toward the use of naturalistic contexts and tasks. In this review, we track this progression from abrupt, artificial stimuli used in extensively controlled laboratory experiments to more naturalistic tasks and stimuli that present a more faithful representation of the real world. We argue that in order to improve ecological validity, naturalistic study designs must consider the complexity of the cognitive phenomenon being studied. Then, we review the current state of "naturalistic" event segmentation studies and critically assess frequently employed movie stimuli. We evaluate recently developed tools like lifelogging and other extended reality technologies to help address the challenges we identified with existing naturalistic approaches. We conclude by offering some guidelines that can be used to design ecologically valid cognitive neuroscience studies of memory and event cognition.

The frequency and cueing mechanisms of involuntary autobiographical memories while driving

Involuntary autobiographical memories (IAMs) have been typically studied with paper diaries, kept for a week or longer. However, such studies are unable to capture the true frequency of IAMs, nor the level of detail that would give new insights into the mechanisms of IAMs. To address this gap, a new audio-recording method was developed and tested on the first author who recorded 674 IAMs while driving a car on a 30-40-minute-long habitual route on 20 occasions. Results revealed very high frequency of IAMs (almost 34 per journey) that were reported more often in response to dynamic (one-off) than static cues. Moreover, a substantial number of memory chains and long-term priming of IAMs by previously encountered incidental stimuli were also recorded. Based on these results, a new theoretical model is proposed in which the occurrence of IAMs is determined by an interplay of factors at the time of the IAM, such as the type of ongoing activity and internal or external triggers, as well as different types of long-term priming. The results also have practical implications for studying mind-wandering and safety issues in driving and aircraft-flying, where periods of concentration are followed by monotony and less demanding tasks.

Guessing as a learning intervention: A meta-analytic review of the prequestion effect

Giving students test questions before they have learned the correct answers (i.e., prequestions) enhances learning. However, existing research has provided conflicting evidence on whether the benefits of prequestions are specific to the initially tested material or if they generalize to new, nontested material. In this review, we summarize the literature on the prequestion effect, describe the attention-based account underlying this effect, report a meta-analysis of the magnitude of the specific and general effects, and explore theoretically and empirically relevant moderator variables that influence the size and direction of the prequestion effect. This preregistered meta-analysis demonstrated a moderate specific effect (g = 0.54, k = 97) but a virtually nonexistent general effect (g = 0.04, k = 91). Overall, the attention-based account received support from some theoretically relevant moderator analyses. Future researchers are encouraged to conduct theoretically motivated studies to help clarify the mechanisms that underlie the attention-enhancing effects of prequestions and to explore the benefits of prequestions in educational domains to establish the extent to which these effects translate into the classroom.

Semantic associations restore neural encoding mechanisms

Lapses in attention can negatively impact later memory of an experience. Attention and encoding resources are thought to decline as more experiences are encountered in succession, accounting for the primacy effect in which memory is better for items encountered early compared to late in a study list. However, accessing prior knowledge during study can facilitate subsequent memory, suggesting a potential avenue to counteract this decline. Here, we investigated the extent to which semantic associations-shared meaning between experiences-can counteract declines in encoding resources. Our hypothesis is that semantic associations restore neural encoding mechanisms, which in turn improves memory. We recorded scalp electroencephalography (EEG) while male and female human participants performed a delayed free recall task. Half of the items from late in each study list were semantically associated with an item presented earlier in the list. We find that semantic associations improve memory specifically for late list items and selectively modulate the neural signals engaged during the study of late list items. Relative to other recalled items, late list items that are subsequently semantically clustered-recalled consecutively with their semantic associate-elicit increased high-frequency activity and decreased low-frequency activity, a hallmark of successful encoding. Our findings demonstrate that semantic associations restore neural encoding mechanisms and improve later memory. More broadly, these findings suggest that prior knowledge modulates the orientation of attention to influence encoding mechanisms.

No position-specific interference from prior lists in cued recognition: A challenge for position coding (and other) theories of serial memory

Position-specific intrusions of items from prior lists are rare but important phenomena that distinguish broad classes of theory in serial memory. They are uniquely predicted by position coding theories, which assume items on all lists are associated with the same set of codes representing their positions. Activating a position code activates items associated with it in current and prior lists in proportion to their distance from the activated position. Thus, prior list intrusions are most likely to come from the coded position. Alternative "item dependent" theories based on associations between items and contexts built from items have difficulty accounting for the position specificity of prior list intrusions. We tested the position coding account with a position-cued recognition task designed to produce prior list interference. Cuing a position should activate a position code, which should activate items in nearby positions in the current and prior lists. We presented lures from the prior list to test for position-specific activation in response time and error rate; lures from nearby positions should interfere more. We found no evidence for such interference in 10 experiments, falsifying the position coding prediction. We ran two serial recall experiments with the same materials and found position-specific prior list intrusions. These results challenge all theories of serial memory: Position coding theories can explain the prior list intrusions in serial recall and but not the absence of prior list interference in cued recognition. Item dependent theories can explain the absence of prior list interference in cued recognition but cannot explain the occurrence of prior list intrusions in serial recall.

Perirhinal cortex automatically tracks multiple types of familiarity regardless of task-relevance

Perirhinal cortex (PrC) has long been implicated in familiarity assessment for objects and corresponding concepts. However, extant studies have focused mainly on changes in familiarity induced by recent exposure in laboratory settings. There is an increasing appreciation of other types of familiarity signals, in particular graded familiarity accumulated throughout one's lifetime. In prior work (Duke et al., 2017, Cortex, 89, 61-70), PrC has been shown to track lifetime familiarity ratings when participants make related judgements. A theoretically important characteristic of familiarity is its proposed automaticity. Support for automaticity comes from a documented impact of recent stimulus exposure on behavioral performance, and on PrC signals, under conditions in which this exposure is not task relevant. In the current fMRI study, we tested whether PrC also tracks lifetime familiarity of object concepts automatically, and whether this type of familiarity influences behavior even when it is not task relevant. During scanning, neurotypical participants (N = 30, age range 18-40, 7 males) provided animacy judgements about concrete object concepts presented at differing frequencies in an initial study phase. In a subsequent test phase, they made graded judgements of recent or lifetime familiarity. Behavioral performance showed sensitivity to lifetime familiarity even when it was not relevant for the task at hand. Across five sets of fMRI analyses, we found that PrC consistently tracked recent and lifetime familiarity of object concepts regardless of the task performed. Critically, while several other temporal-lobe regions also showed isolated familiarity effects, none of them tracked familiarity with the same consistency. These findings demonstrate that PrC automatically tracks multiple types of familiarity. They support models that assign a broad role in the representation of information about object concepts to this structure.

Interpolated retrieval retroactively increases recall and promotes cross-episode memory interdependence

Retrieving existing memories before new learning can lead to retroactive facilitation. Three experiments examined whether interpolated retrieval is associated with retroactive facilitation and memory interdependence that reflects integrative encoding. Participants studied two lists of cue-response word pairs that repeated across lists (A-B, A-B), appeared in list 1 (A-B, -), or included the same cues with changed responses in each list (A-B, A-C). For A-B, A-C pairs, the tasks interpolated between lists required recall of list 1 (B) responses (with or without feedback) or restudy of complete list 1 (A-B) pairs. In list 2, participants only studied pairs (experiment 1) or studied pairs, attempted to detect changed (C) responses, and attempted to recall list 1 responses for detected changes (experiments 2 and 3). On a final cued recall test, participants attempted to recall list 1 responses, indicated whether responses changed between lists, and if so, attempted to recall list 2 responses. Interpolated retrieval was associated with subsequent retroactive facilitation and greater memory interdependence for B and C responses. These correlational findings are compatible with the view that retrieval retroactively facilitates memories, promotes coactivation of existing memories and new learning, and enables integrative encoding that veridically binds information across episodes.

Reap while you sleep: Consolidation of memories differs by how they were sown

Newly formed memories are spontaneously reactivated during sleep, leading to their strengthening. This reactivation process can be manipulated by reinstating learning-related stimuli during sleep, a technique termed targeted memory reactivation. Numerous studies have found that delivering cues during sleep improves memory for simple associations, in which one cue reactivates one tested memory. However, real-life memories often live in rich, complex networks of associations. In this review, we will examine recent forays into investigating how targeted sleep reactivation affects memories within complex paradigms, in which one cue can reactivate multiple tested memories. A common theme across studies is that reactivation consequences do not merely depend on whether memories reside in complex arrangements, but on how memories interact with one another during acquisition. We therefore emphasize how intricate study design details that alter the nature of learning and/or participant intentions impact the outcomes of sleep reactivation. In some cases, complex networks of memories interact harmoniously to bring about mutual memory benefits; in other cases, memories interact antagonistically and produce selective impairments in retrieval. Ultimately, although this burgeoning area of research has yet to be systematically explored, results suggest that the fate of reactivated stimuli within complex arrangements depends on how they were learned.

The role of rehearsal and reminding in the recall of categorized word lists

Most theories of free recall emphasize the importance of retrieval in explaining temporal and semantic regularities in recall; rehearsal mechanisms are often absent or limit rehearsal to a subset of what was last rehearsed. However, in three experiments using the overt rehearsal method, we show clear evidence that just-presented items act as retrieval cues during encoding (study-phase retrieval) with prior related items rehearsed despite well over a dozen intervening items. Experiment 1 examined free recall of categorized and uncategorized lists of 32 words. In Experiments 2 and 3, we presented categorized lists of 24, 48, and 64 words for free recall or cued recall, with the category exemplars blocked in successive list positions (Experiment 2) or randomized throughout the list (Experiment 3). The probability of rehearsing a prior word was affected by its semantic similarity to the just-presented item, and the frequency and recency of its prior rehearsals. These rehearsal data suggest alternative interpretations to well-known recall phenomena. With randomized designs, the serial position curves were reinterpreted by when words were last rehearsed (which contributed to the list length effects), and semantic clustering and temporal contiguity effects at output were reinterpreted by whether words were co-rehearsed during study. The contrast with the blocked designs suggests that recall is sensitive to the relative (not absolute) recency of targeted list items. We discuss the benefits of incorporating rehearsal machinery into computational models of episodic memory, and suggest that the same retrieval processes that generate the recalls are used to generate the rehearsals.

Intention and Monitoring Influence the Content of Memory Reports

OBJECTIVES

While voluntary memories are intended and expected, involuntary memories are retrieved with no intention and are usually unexpected (when one is not waiting for a memory). The present study investigates the effects of retrieval intentionality (wanting to retrieve a memory) and monitoring processes (expecting a memory to appear) on the characteristics of autobiographical memories.

METHODS

To this end, by applying mixed-method analysis of memory descriptions (i.e. combining qualitative with quantitative analyses) we re-analysed the large pool of involuntary and voluntary memories obtained in one previously published study, asking independent judges to rate all the memories on several dimensions reflecting memory accessibility (i.e. the likelihood that a memory can be retrieved).

RESULTS

When discussing our findings, we speculate that there may be several stages of memory retrieval that might be differently influenced by intention and monitoring.

CONCLUSIONS

We discuss the novel hypothesis that there may be two different types of monitoring that operate independently of each other, before and after retrieval, respectively.

Guessing can benefit memory for related word pairs even when feedback is delayed

Trying to guess what the correct answer to a question might be can facilitate future learning of this answer when presented in the form of corrective feedback. One issue that determines the effectiveness of guessing as a learning strategy is the timing of the presentation of feedback: it can be presented either immediately after the guess, or after a delay. Whereas the timing of feedback is of little importance for complex materials such as trivia questions, previous research suggests that for simpler materials such as related word pairs guessing seems to benefit learning only when feedback is immediate. In order to test whether this always has to be the case, we conducted two experiments in which we increased the richness of study materials by superimposing the to-be-learned word pairs over unrelated context pictures. We then manipulated the match between contexts at study and at test (Experiment 1) and at the time of feedback delivery (Experiment 2). Contrary to previous studies showing no benefits of guessing with delayed feedback, our results show that learning related word pairs can benefit from guessing even when feedback is delayed. These benefits of guessing occur if participants are reminded via reinstated contexts of the guessing stage at the time of feedback delivery. Our results help constrain theories of guessing benefits and extend theories of reminding.

Semantic relatedness retroactively boosts memory and promotes memory interdependence across episodes

Two fundamental issues in memory research concern when later experiences strengthen or weaken initial memories and when the two memories become linked or remain independent. A promising candidate for explaining these issues is semantic relatedness. Here, across five paired-associate learning experiments (N=1000), we systematically varied the semantic relatedness between initial and later cues, initial and later targets, or both. We found that learning retroactively benefited long-term memory performance for semantically related words (vs. unshown control words), and these benefits increased as a function of relatedness. Critically, memory dependence between initial and later pairs also increased with relatedness, suggesting that pre-existing semantic relationships promote interdependence for memories formed across episodes. We also found that modest retroactive benefits, but not interdependencies, emerged when subjects learned via studying rather than practice testing. These findings demonstrate that semantic relatedness during new learning retroactively strengthens old associations while scaffolding new ones into well-fortified memory traces.

Reducing age-related Memory Deficits: The Roles of Environmental Support and self-initiated Processing Activities

BACKGROUND

The notion that memory performance in older adults can be boosted by information provided by the environment was proposed by Craik (1983). The suggestion was that age-related memory deficits can be attenuated and sometimes even eliminated by a complementary combination of environmental support and consciously controlled self-initiated activities.

OBJECTIVE

The objective of the present article was to review the subsequent empirical and theoretical work on the topics of environmental support and self-initiated ativities as they relate to the effects of aging on human memory.

DISCUSSION

The notion of schematic support from the person's knowledge base is introduced and its relevance discussed. In addition, the effects of various types of support on encoding and retrieval processes in older adults are desribed, and the increasing theoretical importance of executive processes in reducing age-related memory deficits is discussed.

CONCLUSION

As one main conclusion, it is suggested that self-initiated control processes interact with both information provided by the environment and by the person's knowledge base to improve the effectiveness of encoding and retrieval processing in older adults.

The repetition of errors in recall: a review of four 'fragmentation' experiments

This review reanalyses the data from four experiments originally designed to test the fragmentation hypothesis. Participants were asked to recall triple or quadruple associates, cued by each of their components in turn, and to guess if they could not remember. There were many errors in recall and many of those errors were repetitions of previous errors. This reanalysis focuses, not on the fragmentation hypothesis, but on the repetition of errors. It works backwards through sequences of test trials to discover the best prior match to the responses on each trial. It reports frequencies of different categories of repetition, conditional probabilities of repetition, correct recalls, and the probability of repetition in relation to the lag between trial and match in the test sequence. These results may be summarised as (1) every event (a stimulus or a response or just a retrieval) to which the participant attends is separately recorded in memory, creating an ordered record of those events that have engaged the participant's attention; (2) the compilation of the record is automatic; while attention to a stimulus is at the participant's disposal, the consequent entry into memory is not, and (3) the retrieval of a potential response from memory is spontaneous; that retrieval becomes an overt response if it is compatible with the cue. This makes sense of a number of historic anomalies in the study of recall and informs some contemporary problems in the study of short-term memory.

Predictive processing models and affective neuroscience

The neural bases of affective experience remain elusive. Early neuroscience models of affect searched for specific brain regions that uniquely carried out the computations that underlie dimensions of valence and arousal. However, a growing body of work has failed to identify these circuits. Research turned to multivariate analyses, but these strategies, too, have made limited progress. Predictive processing models offer exciting new directions to address this problem. Here, we use predictive processing models as a lens to critique prevailing functional neuroimaging research practices in affective neuroscience. Our review highlights how much work relies on rigid assumptions that are inconsistent with a predictive processing approach. We outline the central aspects of a predictive processing model and draw out their implications for research in affective and cognitive neuroscience. Predictive models motivate a reformulation of "reverse inference" in cognitive neuroscience, and placing a greater emphasis on external validity in experimental design.

Test position effects on hit and false alarm rates in recognition memory for paintings and words

When old/new recognition memory is tested with equal numbers of studied and nonstudied items and no rewards or instructions that favour one response over the other, there is no obvious reason for response bias. In line with this, Canadian undergraduates have shown, on average, a neutral response bias when we tested them on recognition of common English words. By contrast, most subjects we have tested on recognition of richly detailed images have shown a conservative bias: they more often erred by missing a studied image than by judging a nonstudied image as studied. Here, in an effort to better understand these materials-based bias effects (MBBEs), we examined changes in hit and false alarm (FA) rates (and in sensitivity and bias) from the first to fourth quartile of a recognition memory test in eight experiments in which undergraduates studied words and/or images of paintings. Response bias for images tended to increase across quartiles, whereas bias for words showed no consistent pattern across quartiles. This pattern could be described as an increase in the MBBE over the course of the test, but the underlying patterns for hits and FAs are not easily reconciled with this interpretation. Hit rates decreased over the course of the test for both materials types, with that decline tending to be steeper for images than words. For words, FA rates tended to increase across quartiles, whereas for paintings FA rates did not increase across quartiles. We discuss implications of these findings for theoretical accounts of the MBBE.

Specifying a relationship between semantic and episodic memory in the computation of a feature-based familiarity signal using MINERVA 2

Approaches to modeling episodic recognition memory often imply a separability from semantic memory insofar as an implicit tabula rasa (i.e., blank slate) assumption is apparent in many simulations. This is evident in the common practice of having new test probes correspond to zero memory traces in the store while old test probes correspond to traces representing instances of items' occurrence on a study list. However, in list-learning studies involving word lists, none of the test items would actually correspond to zero items in the person's memory, as all of the test words are generally known to participants, whether old or new. By focusing on a list-learning recognition phenomenon that likely results from feature-based familiarity detection and necessarily involves a role of preexisting knowledge in its mechanisms-the semantic-feature-based recognition without cued recall phenomenon-we show how incorporating preexisting knowledge into the MINERVA 2 model enables it to simulate previously shown empirical patterns with this phenomenon. The simulation patterns reported here raise new theoretical implications worth further exploration, such as the extent to which the variances change in the signal versus the noise distribution when preexisting knowledge is present versus absent in the simulations.

The Dynamics of Subjective Career Success: A Qualitative Inquiry

Current perspectives on career success have yet to show whether and how subjective career success evaluations may change over time and across career phases. By adopting a retrospective life-span approach to careers, our qualitative inquiry into the career experiences of 63 professionals contributes to the temporal understanding of subjective career success by exploring patterns in how subjective career success perceptions and priorities may change over time. The temporal development of subjective career success was explored among early-career, mid-career, and late-career workers by piecing together retrospective evaluations of career success perceptions. Our findings point to common patterns in career success perceptions across the lifespan. Specifically, we found five shift components of career success perceptions during people’s careers: (1) quitting striving for financial success and recognition; (2) an increased focus on personal development across the career; (3) a stronger emphasis on work–life balance across the career; (4) a shift toward being of service to others; and (5) no change in subjective career success components across the career. These patterns reflect ways in which workers engage in motivational self-regulation and the corresponding career goal-setting across the lifespan. The theoretical implications are discussed.

Using the phenomenology of memory for recent events to bridge the gap between episodic and semantic memory

Public events such as celebrity news, tragedies, and political events are widely experienced. Initially at least, memories of these events are "episodic" in nature; however, these events are also stored in associative networks similar to the semantic organization of knowledge (N. R. Brown, 1990, Journal of Experimental Psychology: General, 119[3], 297-314). Thus, these memories provide a novel way of examining how episodically experienced events might become semanticized and integrated into the knowledge base. Younger and older adults rated their subjective memory strength for and answered questions about details of events occurring over the previous 12 years. Participants also rated their phenomenological experience using a modified remember/know paradigm, in which no instructions about usage of the terms were provided. Interestingly, remembered and known items were equal in terms of subjective strength. Know responses were highly accurate, and more so than remember responses. Older and younger adults performed similarly. Participants' own definitions of remember, know, and just familiar revealed that knowing is associated with retrieval from semantic memory, whereas remembering and just familiarity are more associated with event/episodic memory. These results suggest that memory for public events shares phenomenological features with both episodic/event memory and semantic memory. Public events thus allow researchers to examine the complex ways in which storage of novel information can be jointly maintained in both episodic and semantic memory.

The role of prior-event retrieval in encoding changed event features

When people experience everyday activities, their comprehension can be shaped by expectations that derive from similar recent experiences, which can affect the encoding of a new experience into memory. When a new experience includes changes-such as a driving route being blocked by construction-this can lead to interference in subsequent memory. One potential mechanism of effective encoding of event changes is the retrieval of related features from previous events. Another such mechanism is the generation of a prediction error when a predicted feature is contradicted. In two experiments, we tested for effects of these two mechanisms on memory for changed features in movies of everyday activities. Participants viewed movies of an actor performing everyday activities across two fictitious days. Some event features changed across the days, and some features violated viewers' predictions. Retrieval of previous event features while viewing the second movie was associated with better subsequent memory, providing evidence for the retrieval mechanism. Contrary to our hypotheses, there was no support for the error mechanism: Prediction error was not associated with better memory when it was observed correlationally (Experiment 1) or directly manipulated (Experiment 2). These results support a key role for episodic retrieval in the encoding of new events. They also indicate boundary conditions on the role of prediction errors in driving new learning. Both findings have clear implications for theories of event memory.

Judgments of frequency and duration: One or two underlying dimensions?

How often and for how long a certain object was encountered are two distinct questions, requiring two distinct answers. But when humans judge an object to have been presented often, they usually also judge it to have been presented for a long duration. Under certain conditions the reverse is also true: When an object has been presented for a long time, humans think it has been presented often. These mutual influences hint at a single underlying dimension on which judgments of frequency and duration are based. But the judgments also differ in certain respects, which instead speaks for two independent dimensions. In this article, from a novel formal perspective, we revisit arguments for and against unidimensional and two-dimensional models. To determine which of these models is supported empirically, we analyzed all available studies and tested an overlooked but critical condition that would allow us to draw a definitive conclusion. Our evidence speaks against a unidimensional model in all variants.

Spontaneous and deliberate future thinking: a dual process account

In this article, we address an apparent paradox in the literature on mental time travel and mind-wandering: How is it possible that future thinking is both constructive, yet often experienced as occurring spontaneously? We identify and describe two 'routes' whereby episodic future thoughts are brought to consciousness, with each of the 'routes' being associated with separable cognitive processes and functions. Voluntary future thinking relies on controlled, deliberate and slow cognitive processing. The other, termed involuntary or spontaneous future thinking, relies on automatic processes that allows 'fully-fledged' episodic future thoughts to freely come to mind, often triggered by internal or external cues. To unravel the paradox, we propose that the majority of spontaneous future thoughts are 'pre-made' (i.e., each spontaneous future thought is a re-iteration of a previously constructed future event), and therefore based on simple, well-understood, memory processes. We also propose that the pre-made hypothesis explains why spontaneous future thoughts occur rapidly, are similar to involuntary memories, and predominantly about upcoming tasks and goals. We also raise the possibility that spontaneous future thinking is the default mode of imagining the future. This dual process approach complements and extends standard theoretical approaches that emphasise constructive simulation, and outlines novel opportunities for researchers examining voluntary and spontaneous forms of future thinking.

Involuntary autobiographical memories and their relation to other forms of spontaneous thoughts

Involuntary autobiographical memories are memories of personal events that come to mind spontaneously-that is, with no conscious initiation of the retrieval process. Such spontaneously arising memories were long ignored in cognitive psychology, which generally has focused on controlled and strategic forms of remembering, studied in laboratory settings. Recent evidence shows that involuntary memories of past events are highly frequent in daily life, and that they represent a context-sensitive, and associative way of recollecting past events that involves little executive control. They operate by constraints that favour recent events and events with a distinct feature overlap to the current situation, which optimizes the probability of functional relevance to the ongoing situation. In addition to adults, they are documented in young children and great apes and may be an ontogenetic and evolutionary forerunner of strategic retrieval of past events. Findings suggest that intrusive involuntary memories observed clinically after traumatic events should be viewed as a dysfunctional subclass of otherwise functional involuntary autobiographical memories. Because of their highly constrained, situation-dependent and automatic nature, involuntary autobiographical memories form a distinct category of spontaneous thought that cannot be equated with mind wandering. This article is part of the theme issue 'Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation'.

Differential Involvement of Working Memory Capacity and Fluid Intelligence in Verbal Associative Learning as a Possible Function of Strategy Use

The paired-associate paradigm has a long history of use in basic and applied research on human memory and learning. A number of studies have shown that people differ in the strategies they use to encode information in paired-associate tasks and, importantly, that strategies differ in their effectiveness. What is not so well documented is how different strategies may affect the cognitive processes assessed by paired-associate tasks. In this study, we submitted archival data to distributional and latent class analyses to infer strategy use and classify participants as elaborators or nonelaborators. We then used regression analyses within subgroups to identify differences in dependence on fluid intelligence and working memory capacity. To the extent that our classification was accurate, the results suggest that paired-associate learning is more reliant on fluid intelligence when elaborative rehearsal is used and more reliant on working memory capacity when nonelaborative strategies are used. To offer further evidence of the validity of our approach, we also investigated correlations between strategy use and fluid intelligence and working memory capacity. In accord with prior research, we found that cognitive abilities were positively correlated with what we infer to be differences in strategy use. That the cognitive processes assessed by verbal paired-associate tasks may vary as a function of strategy use should be a concern for all researchers and practitioners who use such tasks.

Noting a difference: change in social context prompts spontaneous recall in 46-month-olds, but not in 35-month-olds

An experimental paradigm has shown that it is possible to activate spontaneous memories in children by having them re-visit the setting in which they were introduced to a memorable event. Nevertheless, the most important cues for spontaneous recall remain undetermined. In response, we investigated the importance of the experimenter by introducing 35-month-olds (n = 62) and 46-month-olds (n = 62) to the same or a new person after one week. We expected that altering the experimenter would result in fewer recollections through reducing the overlap of cues between encoding and testing. In contrast, the manipulation affected the two age groups differently: no effect of condition was seen in the 35-month-olds, whereas the 46-month-olds performed better, when the experimenter had changed, suggesting a sensitivity to change and an ability to update their knowledge of the event. We replicated previous findings demonstrating that both age groups exhibited spontaneous recollections.

Deficits in Spontaneous Cognition as an Early Marker of Alzheimer's Disease

In the absence of a pharmacological cure, finding the most sensitive early cognitive markers of Alzheimer's disease (AD) is becoming increasingly important. In this article we review evidence showing that brain mechanisms of spontaneous, but stimulus-dependent, cognition overlap with key hubs of the default mode network (DMN) that become compromised by amyloid pathology years before the clinical symptoms of AD. This leads to the formulation of a novel hypothesis which predicts that spontaneous, but stimulus-dependent, conscious retrieval processes, that are generally intact in healthy aging, will be particularly compromised in people at the earliest stages of AD. Initial evidence for this hypothesis is presented across diverse experimental paradigms (e.g., prospective memory, mind-wandering), and new avenues for research in this area are outlined.

The role of attentional fluctuation during study in recollecting episodic changes at test

Changes in stimulus features across episodes can lead to proactive interference. One potential way to avoid such interference is to detect and later recollect changes. The Memory-for-Change framework assumes that attention during encoding is necessary for detecting and later recollecting change. We tested this assumption in the current experiment by assessing the covariation of attention and change recollection in a large undergraduate sample (N=132). Participants studied a list of word pairs comprised of four seamless blocks. Some word pairs repeated across all four blocks (A-B⁴), some were unique to each block (C-D), and some pairs repeated across the first three blocks with a changed response in the fourth block (A-B³, A-D). To measure attention during study, participants periodically responded to probes asking whether they were on- or off-task. Participants then completed a cued recall test of responses from the fourth study block. To measure change recollection, participants were asked to identify which pairs changed during study and to report the earlier responses for pairs they identified as changed. Replicating prior findings, recollecting change was associated with proactive facilitation in recall of the most recent responses. Extending these findings, the frequency of on-task reports was positively associated with cued recall accuracy and change recollection in both within- and between-subjects comparisons. Together, these findings implicate a critical role for self-reported attention during study in change recollection, which is associated with proactive facilitation in recall of changed responses.

Structured word-lists as a model of basic schemata: deviations from content and order in a repeated event paradigm

Repeated events are common in everyday life, but relatively neglected as a topic within memory psychology. In two samples of adults, we investigated memory for repeated, schema-establishing simple events (operationalised as structured word-lists), and the effects of deviations within those events. We focused on the effects of deviations from two core dimensions of schema: content and order. Across three successive word-list events, we established and reinforced a basic list schema by always presenting three content categories in the same order. These expectations were violated in a fourth and final word-list. We measured the effects on memory of both the violating and the schema-establishing lists in multiple recall attempts over a period of one month. We measured correct recall, misattribution errors, metacognitive awareness of list-organisation and deviations, and recall organisation. Across all delays and across all word-lists (not only the final one), content changes increased recall, whereas order changes decreased recall. Participants were also more aware of content changes than order changes. These disparate effects suggest that the two types of schema-deviations may have qualitatively different effects on memory for specific instances of a repeated generic event. Cognitive processes underlying memory for typical and exceptional instances of repeated events are discussed.

A Fast Visual Recognition Memory System in Humans Identified Using Intracerebral ERP

One key item of information retrieved when surveying our visual world is whether or not objects are familiar. However, there is no consensus on the respective roles of medial temporal lobe structures, particularly the perirhinal cortex (PRC) and hippocampus. We considered whether the PRC could support a fast recognition memory system independently from the hippocampus. We recorded the intracerebral electroencephalograph activity of epileptic patients while they were performing a fast visual recognition memory task, constraining them to use their quickest strategy. We performed event-related potential (ERP) and classification analyses. The PRC was, by far, the earliest region involved in recognition memory. This activity occurred before the first behavioral responses and was found to be related to reaction times, unlike the hippocampus. Single-trial analyses showed that decoding power was equivalent in the PRC and hippocampus but occurred much earlier in the PRC. A critical finding was that recognition memory-related activity occurred in different frontal and parietal regions, including the supplementary motor area, before the hippocampus. These results, based on ERP analyses, suggest that the human brain is equipped with a fast recognition memory system, which may bypass the hippocampus and in which the PRC plays a critical role.

RECAPP-XPR: A smartphone application for presenting and recalling experimentally controlled stimuli over longer timescales

We report two experiments that used smartphone applications for presenting and recalling verbal stimuli over extended timescales. In Experiment 1, we used an iPhone application that we had developed, called RECAPP-XPR, to present 76 participants with a single list of eight words presented at a rate of one word every hour, followed by a test of free recall an hour later. The experiment was exceptionally easy to schedule, taking only between 5 and 10 min to set up using a web-based interface. RECAPP-XPR randomly samples the stimuli, presents the stimuli, and collects the free recall data. The stimuli disappear shortly after they have been presented, and RECAPP-XPR collects data on when each stimulus was viewed. In Experiment 2, the study was replicated using the widely used image-sharing application Snapchat. A total of 197 participants were tested by 38 student experimenters, who manually presented the stimuli as “snaps” of experimentally controlled stimuli using the same experimental rates that had been used in Experiment 1. Like all snaps, these stimuli disappeared from view after a very short interval. In both experiments, we observed significant recall advantages for the first and last list items (primacy and recency effects, respectively), and there were clear tendencies to make more transitions at output between near-neighboring items, with a forward-ordered bias, consistent with temporal contiguity effects. The respective advantages and disadvantages of RECAPP-XPR and Snapchat as experimental software packages are discussed, as is the relationship between single-study-list smartphone experiments and long-term recency studies of real-world events.

Contiguity in episodic memory

Contiguity is one of the major predictors of recall dynamics in human episodic memory. But there are many competing theories of how the memory system gives rise to contiguity. Here we provide a set of benchmark findings for which any such theory should account. These benchmarks are drawn from a review of the existing literature as well as analyses of both new and archival data. They include 34 distinct findings on how various factors including individual and group differences, task parameters, and type of stimuli influence the magnitude of the contiguity effect. We will see that contiguity is observed in a range of tasks including recognition, paired associates, and autobiographical recall and across a range of time scales including minutes, days, weeks, and years. The broad pattern of data point toward a theory in which contiguity arises from fundamental memory mechanisms that encode and search an approximately time scale invariant representation of temporal distance.

Enhanced spontaneous retrieval of cues from emotional events: An ERP study

Recent evidence points to enhanced episodic memory retrieval not only for emotional items but also for neutral information encoded in emotional contexts. However, prior research only tested instructed explicit recognition, and hence here we investigated whether memory retrieval is also heightened for cues from emotional contexts when retrieval is not explicitly probed. During the first session of a two-session experiment, neutral objects were presented on different background scenes varying in emotional and neutral contents. One week later, objects were presented again (with no background) intermixed with novel objects. In both sessions, participants were instructed to attentively watch the stimuli (free viewing procedure), and during the second session, ERPs were also collected to measure the ERP Old/New effect, an electrophysiological correlate of episodic memory retrieval. Analyses were performed using cluster-based permutation tests in order to identify reliable spatio-temporal ERP differences. Based on this approach, old relative to new objects, were associated with larger ERP positivity in an early (364-744 ms) and late time window (760-1148 ms) over distinct central electrode clusters. Interestingly, significant late ERP Old/New differences were only observed for objects previously encoded with emotional, but not neutral scenes (504 to 1144 ms). Because these ERP differences were observed in a non-instructed retrieval context, our results indicate that long-term, spontaneous retrieval for neutral objects, is particularly heightened if encoded within emotionally salient contextual information. These findings may assist in understanding mechanisms underlying spontaneous retrieval of emotional associates and the utility of ERPs to study maladaptive involuntary memories in trauma- and stress-related disorders.

How intention to retrieve a memory and expectation that a memory will come to mind influence the retrieval of autobiographical memories

While involuntary memories are retrieved with no intention and are usually unexpected (when one is not waiting for a memory to arise), voluntary memories are intended and expected (when one is searching and waiting for a memory to arise). The present study aimed to investigate the effects of retrieval intentionality (i.e. wanting to retrieve a memory) and monitoring processes (i.e. waiting for a memory to appear) during autobiographical memory retrieval. In addition, we introduced two novel laboratory conditions that have not been used in previous research on voluntary memories: in the first, participants were asked to report anything they could think of in response to each cue word; in the second, they could skip a word if nothing came to mind. These novel manipulations allowed us to differentiate between voluntary memories retrieved in response to experimenter-generated cues (when participants were forced to provide a memory or a thought for each cue) and self-selected cues (when participants were free to not answer a cue if they found it too difficult). We found that highly accessible memories were mostly experienced when retrieval was involuntary and unexpected, while memories with low accessibility were accessed through intentional retrieval and monitoring processes. Response times for memories recalled in the experimenter-generated cue conditions were longer compared to the self-selected cue conditions. This novel finding shows that experimenter-generated recall favours memories with low accessibility; it further supports the idea that, in a substantial number of trials, voluntary memories are directly rather than effortfully retrieved. The idea that the driving force behind differences between involuntary and voluntary memories is not the intention per se is further discussed.

A strength-based mirror effect persists even when criterion shifts are unlikely

In single-item recognition, the strength-based mirror effect (SBME) is reliably obtained when encoding strength is manipulated between lists or participants. Debate surrounds the degree to which this effect is due to differentiation (e.g., Criss Journal of Memory and Language, 55, 461-478, 2006) or criterion shifts (e.g., Hicks & Starns Memory & Cognition, 42, 742-754, 2014). Problematically, differing underlying control processes may be equally capable of producing an SBME. The ability of criterion shifts to produce an SBME has been shown in prior work where differentiation was unlikely. The present work likewise produces an SBME under conditions where criterion shifts are unlikely. Specifically, we demonstrate that an SBME can be elicited without the typical number of trials needed to adjust one's decision criterion (Experiments 1, 2, and 5) and using encoding manipulations that do not explicitly alert participants that their memory quality has changed (Experiments 3 and 4). When taken in the context of the broader literature, these results demonstrate the need to prioritize memory models that can predict SBMEs via multiple underlying processes.

The role of retrieval during study: Evidence of reminding from self-paced study time

The reminding effect (Tullis, Benjamin, & Ross, Journal of Experimental Psychology: General, 143[4], 1526-1540, 2014) describes the increase in recall of a studied word when a related word is presented later in the study list. However, because the process of reminding is thought to occur during study, measures of test performance are indirect indicators of the process of reminding and are subject to influences that arise during testing. The present research seeks evidence of reminding during encoding. In two experiments, self-paced study times were used to index the online process of reminding. In Experiment 1, pairs of repeated words, related words, and unrelated words were included in a study list. Study times were shorter for words related to prior words in the list, but only when the lag between those two words was short. Relatedness affected study time by inspiring a reduction in the threshold for termination of study for related words under massed conditions. Experiment 2 replicated the reduction in study time for related words and further showed that the study time allotted to an associate of an earlier item predicted better memory for that earlier word on a cued-recall test. In this experiment, an advantage in memory was observed for related words, and self-paced study time of one word during encoding was predictive of later memory for a related word. These results suggest a link between the action of reminding at study, as indexed by changes in the distribution of study time, and later benefits to remembering, as revealed by the reminding effect.

The tendency for experiencing involuntary future and past mental time travel is robustly related to thought suppression: an exploratory study

Involuntary mental time travel (MTT) refers to projecting oneself into the past or into the future without prior conscious effort. The previous studies have shown high inter-individual variability in the frequency of involuntary MTT, but a few systematic studies exist. In three exploratory studies, we investigated the relation between individual differences in experiencing involuntary past and future MTT, and selected emotional and cognitive processes, with a special focus on thought suppression. Across all three studies, thought suppression emerged as a robust predictor of involuntary MTT above and beyond emotion-related variables, mind-wandering, daydreaming styles, and demographic variables. Findings from Studies 1 and 2 showed that higher thought suppression consistently predicted both more frequent involuntary past and future MTT across an American and a Danish sample, whereas rumination and emotion regulation were less consistently related to involuntary MTT. In Study 3, thought suppression reliably predicted more frequent involuntary MTT, even when controlling for mind-wandering, as well as for positive and negative daydreaming styles, which were all related to greater involuntary MTT. Overall, the individual differences assessed showed similar relationships to the tendency for having past and future involuntary MTT, with the possible exception of daydreaming styles, which appeared more strongly related to future-directed involuntary MTT.

Temporal Proximity Links Unrelated News Events in Memory

Some memories are linked such that recalling one can trigger the retrieval of another. What determines which memories are linked? Some models predict that simply occurring close together in time is sufficient for links to form between memories. A competing theory suggests that temporal proximity is generally not sufficient, and existing evidence for such links is an artifact of using chainlike lists of items in artificial laboratory tasks. To test these competing accounts, we asked subjects to recall news stories that they had encountered over the past 2 years (Experiment 1) or 4 months (Experiment 2). In both experiments, subjects showed a strong bias to successively recall stories that appeared in the news within days of each other—even after accounting for the fact that stories that occur close in time tend to be semantically related. By moving beyond laboratory tasks, this research solidifies the foundation of contemporary memory theory.

Conversational Time Travel: Evidence of a Retrospective Bias in Real Life Conversations

We examined mental time travel reflected onto individuals' utterances in real-life conversations using a naturalistic observation method: Electronically Activated Recorder (EAR, a portable audio recorder that periodically and unobtrusively records snippets of ambient sounds and speech). We introduced the term conversational time travel and examined, for the first time, how much individuals talked about their personal past versus personal future in real life. Study 1 included 9,010 sound files collected from 51 American adults who carried the EAR over 1 weekend and were recorded every 9 min for 50 s. Study 2 included 23,103 sound files from 33 young and 48 healthy older adults from Switzerland who carried the EAR for 4 days (2 weekdays and 1 weekend, counterbalanced). 30-s recordings occurred randomly throughout the day. We developed a new coding scheme for conversational time travel: We listened to all sound files and coded each file for whether the participant was talking or not. Those sound files that included participant speech were also coded in terms of their temporal focus (e.g., past, future, present, time-independent) and autobiographical nature (i.e., about the self, about others). We, first, validated our coding scheme using the text analysis tool, Linguistic Inquiry and Word Count. Next, we compared the percentages of past- and future-oriented utterances about the self (to tap onto conversational time travel). Results were consistent across all samples and showed that participants talked about their personal past two to three times as much as their personal future (i.e., retrospective bias). This is in contrast to research showing a prospective bias in thinking behavior, based on self-report and experience-sampling methods. Findings are discussed in relation to the social functions of recalling the personal past (e.g., sharing memories to bond with others, to update each other, to teach, to give advice) and to the directive functions of future-oriented thought (e.g., planning, decision making, goal setting that are more likely to happen privately in the mind). In sum, the retrospective bias in conversational time travel seems to be a functional and universal phenomenon across persons and across real-life situations.

How the stimulus influences mind wandering in semantically rich task contexts

What do we think about when we mind wander and where do these thoughts come from? We tested the idea that semantically rich stimuli yield patterns of mind wandering that are closely coupled with the stimuli compared to being more internally triggered. We analyzed the content of 949 self-reported zone outs (1218 thoughts) and 519 of their triggers from 88 participants who read an instructional text and watched a film for 20 min each. We found that mind wandering associated with memory retrieval was more frequent than prospection and introspection across both stimuli. Over 70% of autobiographical and semantic memory retrievals were triggered by the content of the stimuli, compared to around 30% for prospective and introspective thoughts. Further, latent semantic analysis revealed that semantic and unspecific memories were more "semantically" similar to their triggers than prospective and introspective thoughts, suggesting that they arise from spontaneous associations with the stimulus. These findings suggest a re-evaluation of how internal concerns and the external world give rise to mind wandering and emphasize the importance of studying mind wandering in semantically rich contexts akin to much of the real world.

Memory guides the processing of event changes for older and younger adults

Memory for related past experiences can guide current perceptions. However, memory can lead one astray if situational features have changed. Thus, to adaptively use memory to guide perception, one needs to retrieve relevant memories and also to register differences between remembered and current events. Event Memory Retrieval and Comparison Theory proposes that observers associatively activate memories of related previous episodes, and that this guides their ongoing perception. Conflicts between previous and current event features can hurt immediate performance, but if changes are registered and encoded they can lead to highly effective encoding of the prior event, current event, and their relationship. Disruption of these mechanisms could play a role in older adults' greater susceptibility to event memory interference. Two experiments tested these hypotheses by asking participants to watch movies depicting two fictive days of an actor. Some activities were repeated across days, others were repeated with a changed feature (e.g., waking up to an alarm clock or a phone alarm), and others were performed only on Day 2. One week after watching the Day 2 movie, participants completed a cued-recall test. Changes that participants detected but did not remember led to proactive interference in recall, but changes that were successfully detected and remembered led to facilitation. Younger adults detected and remembered more changes than older adults, which partly explained older adults' differential memory deficit for changed activities. These findings suggest a role for episodic reminding in event perception and a potential source of age differences in event memory. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Neural activation and memory for natural scenes: Explicit and spontaneous retrieval

Stimulus repetition elicits either enhancement or suppression in neural activity, and a recent fMRI meta-analysis of repetition effects for visual stimuli (Kim, 2017) reported cross-stimulus repetition enhancement in medial and lateral parietal cortex, as well as regions of prefrontal, temporal, and posterior cingulate cortex. Repetition enhancement was assessed here for repeated and novel scenes presented in the context of either an explicit episodic recognition task or an implicit judgment task, in order to study the role of spontaneous retrieval of episodic memories. Regardless of whether episodic memory was explicitly probed or not, repetition enhancement was found in medial posterior parietal (precuneus/cuneus), lateral parietal cortex (angular gyrus), as well as in medial prefrontal cortex (frontopolar), which did not differ by task. Enhancement effects in the posterior cingulate cortex were significantly larger during explicit compared to implicit task, primarily due to a lack of functional activity for new scenes. Taken together, the data are consistent with an interpretation that medial and (ventral) lateral parietal cortex are associated with spontaneous episodic retrieval, whereas posterior cingulate cortical regions may reflect task or decision processes.

Making remembering more memorable

Memory retrieval is a cognitive operation that itself can be remembered or forgotten, with potentially important consequences. To study memory for prior remembering, we had participants first study target words (e.g., bark) alongside semantically related cue words (e.g., dog). Then, on Test 1, participants retrieved targets in response to either the study cue or a changed cue that was semantically related to a homograph of the target (e.g., birch). Finally, on Test 2, participants retrieved all targets in response to the original study cues, and participants judged whether targets were previously retrieved on Test 1. As in previous research, cue change on Test 1 rendered target retrievals less memorable, suggesting context changes harm memory for prior remembering. We hypothesised that the negative effect of context change could be ameliorated by reminding participants of the original study cues during Test 1. We had participants either retrieve (Experiments 1 and 3, Ns = 46 and 62) or view (Experiment 2, N = 118) the study cue following each target retrieval. Reminding significantly reduced the negative effect of cue change, with self-generation being especially potent. This indicates that reminding can make remembering more memorable in the face of context change.

Serial position, output order, and list length effects for words presented on smartphones over very long intervals

Three experiments examined whether or not benchmark findings observed in the immediate retrieval from episodic memory are similarly observed over much greater time-scales. Participants were presented with experimentally-controlled lists of words at the very slow rate of one word every hour using an iPhone recall application, RECAPP, which was also used to recall the words in either any order (free recall: Experiments 1 to 3) or the same order as presented (serial recall: Experiment 3). We found strong temporal contiguity effects, weak serial position effects with very limited recency, and clear list length effects in free recall; clear primacy effects and classic error gradients in serial recall; and recency effects in a final two-alternative forced choice recognition task (Experiments 2 and 3). Our findings extend the timescales over which temporal contiguity effects have been observed, but failed to find consistent evidence for strong long-term recency effects with experimenter-controlled stimuli.

How intention and monitoring your thoughts influence characteristics of autobiographical memories

Involuntary autobiographical memories come to mind effortlessly and unintended, but the mechanisms of their retrieval are not fully understood. We hypothesize that involuntary retrieval depends on memories that are highly accessible (e.g., intense, unusual, recent, rehearsed), while the elaborate search that characterizes voluntary retrieval also produces memories that are mundane, repeated or distant - memories with low accessibility. Previous research provides some evidence for this 'threshold hypothesis'. However, in almost every prior study, participants have been instructed to report only memories while ignoring other thoughts. It is possible that such an instruction can modify the phenomenological characteristics of involuntary memories. This study aimed to investigate the effects of retrieval intentionality (i.e., wanting to retrieve a memory) and selective monitoring (i.e., instructions to report only memories) on the phenomenology of autobiographical memories. Participants were instructed to (1) intentionally retrieve autobiographical memories, (2) intentionally retrieve any type of thought (3) wait for an autobiographical memory to spontaneously appear, or (4) wait for any type of thought to spontaneously appear. They rated the mental content on a number of phenomenological characteristics both during retrieval and retrospectively following retrieval. The results support the prediction that highly accessible memories mostly enter awareness unintended and without selective monitoring, while memories with low accessibility rely on intention and selective monitoring. We discuss the implications of these effects.

The future is now: the impact of present fluency in judgments about the future

Recent research has emphasised the role of episodic memory in both remembering past events and in envisaging future events. On the other hand, it has been repeatedly shown that judgments about past events are affected by the fluency with which retrieval cues are processed. In this paper we investigate whether perceptual fluency also plays a role in judgments about future events. For this purpose we conducted four experiments. The first experiment replicated recent findings showing that stimuli that are processed fluently tend to be wrongly recognised as having been encountered in the past outside the laboratory walls [Brown, A. S., & Marsh, E. J. (2009). Creating illusions of past encounter through brief exposure. Psychological Science, 20, 534-538. doi: 10.1111/j.1467-9280.2009.02337.x ]. Two follow-up experiments using Brown and Marsh's [(2009). Creating illusions of past encounter through brief exposure. Psychological Science, 20, 534-538. doi: 10.1111/j.1467-9280.2009.02337 ] task tested the influence of perceptual fluency on future judgments. The fourth and last experiment was designed to rule out a potential confounding factor in the two previous experiments. Across experiments, we found that people rely on fluency when making judgments about events that are yet to come. These results suggest that fluency is an equally valid cue for past and future judgments.

Implicit and Explicit Memory Factors in Cumulative Structural Priming

Although researchers have argued that short-term structural priming is driven by both implicit and explicit memory processes, accounts of longer-term structural priming tend to focus on implicit memory processes. We explore this claim in five experiments. In the first two experiments, we replicate the finding that stronger cumulative structural priming is observed for the prepositional object (PO) construction than for the double object (DO) construction. The next three experiments explore the possibility that explicit memory effects may contribute to cumulative priming. The results of these experiments suggest that any explicit memory effects on cumulative priming are likely to be very weak. We conclude by conducting an analysis across all 5 experiments, and find that an examination of individual participants’ base rates of DO production helps to explain the circumstances under which cumulative priming for the DO and PO will be observed.