Trial-and-error learning improves source memory among young and older adults

Trial-and-error learning, relative to errorless learning, has been shown to impair memory among older adults, despite evidence from young adults that errors may afford memorial benefits through richer encoding. However, previous studies on the effects of errorless versus trial-and-error learning in older adults has required production of errors based on perceptual cues. We hypothesized that producing errors conceptually associated with targets would boost memory for the encoding context in which information was studied, especially for older adults who do not spontaneously elaborate on targets at encoding. We report two studies examining the impact of generating errors during learning on source memory among young and older adults, with a process dissociation procedure employed in Study 1, and source memory assessed directly in Study 2. In both studies, participants were shown semantic category cues and generated an exemplar either with or without errors. In Study 1, for both age groups trial-and-error learning was associated with lower familiarity-based memory and higher recollection-based memory relative to errorless learning, and the latter effect was more marked for older than younger adults. Similarly, in Study 2, trial-and-error learning was associated with better source memory relative to errorless learning, particularly for the older adults. We argue that trial-and-error learning can enhance source memory and confer memorial benefits when making such errors facilitates semantic elaboration, especially for older adults who do not spontaneously engage in strategic encoding.     

Effects of emotion on item and source memory in young and older adults

Emotional experiences are easier to remember than neutral ones, but whether memory for all aspects of an experience is improved by emotion remains unclear. Some researchers have argued that the influence of emotion on memory is different for item than for source information, whereas others have argued that emotion affects both similarly. Also, whether item and source memory are affected by emotion in older people in the same way as in young people is currently unclear. We examined item and source memory for emotional and neutral materials in young and older adults. Memory for emotional items was superior to memory for neutral items, whereas there was no difference in source memory. Overall, item and source memory were poorer in older people than in young people, but emotion seemed to have a similar effect on both age groups. Although emotional content was remembered better than neutral content, this benefit did not apply to source memory. However, varying the emotionality of the source (i.e., the voice in Experiment 3) improved memory for the source, and this effect was greater in young than in older people. Tone of voice had no effect on item memory in older people, but the effect was variable in the young and may depend on the extent to which the tone of voice moderates the interpretation of the content.     

Self-initiated object-location memory in young and older adults

The present study explored self-initiated object-location memory in ecological contexts, as aspect of memory that is largely absent from the research literature. Young and older adults memorized objects-location associations they selected themselves or object-location associations provided to them, and elaborated on the strategy they used when selecting the locations themselves. Retrieval took place 30 min and 1 month after encoding. The results showed an age-related decline in self-initiated and provided object-location memory. Older adults benefited from self-initiation more than young adults when tested after 30 min, while the benefit was equal when tested after 1 month. Furthermore, elaboration enhanced memory only in older adults, and only after 30 min. Both age groups used deep encoding strategies on the majority of the trials, but their percentage was lower in older adults. Overall, the study demonstrated the processes involved in self-initiated object-location memory, which is an essential part of everyday functioning.     

Implicit and explicit memory in young and older adults

In three experiments, young and older adults were compared on both implicit and explicit memory tasks. The size of repetition priming effects in word completion and in perceptual identification tasks did not differ reliably across ages. However, age-related decrements in performance were obtained in free recall, cued recall, and recognition. These results, similar to those observed in amnesics, suggest that older adults are impaired on tasks which require conscious recollection but that memory which depends on automatic activation processes in relatively unaffected by age.     

Feature memory and binding in young and older adults

Intact memory for complex events requires not only memory for particular features (e.g., item, location, color, size), but also intact cognitive processes for binding the features together. Binding provides the memorial experience that certain features belong together. The experiments presented here were designed to explicate these as potentially separable sources of age-associated changes in complex memory—namely, to investigate the possibility that age-related changes in memory for complex events arise from deficits in (1) memory for the kinds of information that comprise complex memories, (2) the processes necessary for binding this information into complex memories, or (3) both of these components. Young and older adults were presented with colored items located within an array. Relative to young adults, older adults had a specific and disproportionate deficit in recognition memory for location, but not for item or for color. Also, older adults consistently demonstrated poorer recognition memory for bound information, especially when all features were acquired intentionally. These feature and binding deficits separately contribute to what have been described as older adults’ context and source memory impairments.     

Self-initiated spatial working memory in young and older adults

The age-related decline in working memory (WM) has been studied extensively. Yet, research has focused mainly on one aspect of memory, in which older adults memorised information provided to them, neglecting the frequent everyday behaviour in which memory is self-initiated (SI), meaning that individuals memorise information they selected themselves. The present study used a modified spatial span task in which young and older adults memorised spatial sequences they constructed themselves, or random sequences provided to them. The results revealed that young and older adults carefully planned and constructed structured spatial sequences, by minimising distances between successive locations, and by selecting sequences with fewer path crossings and with more linear shapes. Older adults constructed sequences that were even more structured in some aspects. Young and older adults benefited from self-initiation to the same extent, showing similar age-related declines in SI and provided spatial WM. Overall, the study shows that older adults have access to metacognitive knowledge on the structure of efficient WM representations that benefit accuracy, and shows that older adults can use strategic encoding processes efficiently when encoding is SI. More generally, SI WM explores an important aspect of behaviour, demonstrating how older adults shape their environment to facilitate cognitive functioning.     

Self-reference enhances relational memory in young and older adults

The present study investigated the influence of self-reference on two kinds of relational memory, internal source memory and associative memory, in young and older adults. Participants encoded object–location word pairs using the strategies of imagination and sentence generation, either with reference to themselves or to a famous other (i.e., George Clooney or Oprah Winfrey). Both young and older adults showed memory benefits in the self-reference conditions compared to other-reference conditions on both tests, and the self-referential effects in older adults were not limited by low memory or executive functioning. These results suggest that self-reference can benefit relational memory in older adults relatively independently of basic memory and executive functions.     

Metamemorial predictors of memory performance in young and older adults

The relationship between aspects of knowledge about memory and immediate and delayed recall on prose and word-list tasks was examined. Ss were 100 young and 100 older adults. Vocabulary ability was screened. Memory knowledge was assessed by the Metamemory in Adulthood (MIA) scale and the Short Inventory of Memory Experiences (SIME). Capacity and change measures of the MIA correlated with most dimensions of the SIME for both age groups. The anxiety measure of the MIA correlated with SIME measures only for the young. Regression analyses showed that strategy (MIA) predicted performance only for young adults, change (MIA) predicted performance only for older adults, and capacity (MIA) predicted performance for both age groups. Metamemory variables accounted for equivalent amounts of variance in both prose and word-list tasks, although there was an indication that prediction was slightly better for prose. Future researchers need to address the apparent increase in affect-related predictors of memory performance.     

Evidence for a detrimental relationship between hypertension history, prospective memory, and prefrontal cortex white matter in cognitively normal older adults

Hypertension affects many older adults and is associated with impaired neural and cognitive functioning. We investigated whether a history of hypertension was associated with impairments to prospective memory, which refers to the ability to remember to perform delayed intentions, such as remembering to take medication. Thirty-two cognitively normal older adult participants with or without a history of hypertension (self-reported) performed two laboratory prospective memory tasks, one that relied more strongly on executive control (nonfocal prospective memory) and one that relied more strongly on spontaneous memory retrieval processes (focal prospective memory). We observed hypertension-related impairments for nonfocal, but not focal, prospective memory. To complement our behavioral approach, we conducted a retrospective analysis of available structural magnetic resonance imaging data. Lower white matter volume estimates in the anterior prefrontal cortex were associated with lower nonfocal prospective memory and with a history of hypertension. A history of hypertension may be associated with worsened executive control and lower prefrontal white matter volume. The translational implication is that individuals who must remember to take antihypertensive medications and to monitor their blood pressure at home may be impaired in the executive control process that helps to support these prospective memory behaviors.     

Both young and older adults discount suggestions from older adults on a social memory test

In the present study, we examined the impacts of participant age and confederate age on social memory processes. During a collaborative recall phase, young and older adult participants were exposed to the erroneous memory reports of a young or an older adult confederate. On a subsequent individual recall test, young and older adult participants were equally likely to incorporate the confederates’ erroneous suggestions into their memory reports, suggesting that participant age had a minimal effect on social memory processes. However, confederate age did have a marked effect: Young adult participants were less likely to incorporate misleading suggestions from older adult confederates and less likely to report “remembering” items suggested by older adult confederates. Critically, older adult participants were also less likely to incorporate misleading information from fellow older adult confederates. Both young and older adult participants discounted older adult confederates’ contributions to a memory test.     

Mediator-based encoding strategies in source monitoring in young and older adults

Past research has examined the contribution of mediator-based encoding strategies (interactive imagery and sentence generation) to individual (particularly age-related) differences in associative memory exclusively in the paired-associates paradigm. In the present study, we examined young and older adults' mediator-based strategy use on source-monitoring tasks. Participants spontaneously used mediator-based strategies to encode about 30% to 40% of word-source pairs and were able to follow instructions to use the specific mediator-based strategy of interactive imagery; mediator-based strategy use was associated with higher source memory and explained variance in source memory. There were no age-related differences in the patterns of mediator-based strategy production and utilization. Age-related differences in source memory were explained by age-related declines in the ability to bind information in memory (incidental memory for digit-symbol associations) but not by encoding strategy production. Results underscore the importance of assessing encoding strategy use for understanding individual differences in source memory. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Electrophysiological response during source memory decisions in older and younger adults

We recorded event-related potentials (ERPs) as individuals made source monitoring decisions in a paradigm in which the influence of item familiarity and goal relevance could be separately evaluated. Younger and older adults read a list of words and subsequently distinguished these words from foils in a running recognition test in which some foils were repeated after a lag of 6 items, creating familiar lures. Behaviorally, older and younger adults performed equally well in the recognition of study words and the rejection of singly presented foils. However, older adults were more likely to respond to the familiar lures as though they had come from the study list, thus producing the expected group difference in source-monitoring error. For younger adults the ERPs elicited by the targeted study words were maximal at posterior sites and significantly greater than those elicited by either familiar lures or foils. Older adults generated far less differentiated ERP waveforms but with a markedly greater amplitude at frontal sites. We interpret this frontal maximum in the context of poorer source monitoring as suggesting that older adults are more dependent on controlled processes to make discriminations that seem to occur much earlier and more automatically for younger adults.     

Viewing instructions impact emotional memory differently in older and young adults

The current study examines how the instructions given during picture viewing impact age differences in incidental emotional memory. Previous research has suggested that older adults' memory may be better when they make emotional rather than perceptual evaluations of stimuli and that their memory may show a positivity bias in tasks with open-ended viewing instructions. Across two experiments, participants viewing photographs either received open-ended instructions or were asked to make emotionally focused (Experiment 1) or perceptually focused (Experiment 2) evaluations. Emotional evaluations had no impact on older adults' memory, whereas perceptual evaluations reduced older adults' recall of emotional, but not of neutral, pictures. Evidence for the positivity effect was sporadic and was not easier to detect with open-ended viewing instructions. These results suggest that older adults' memory is best when the material to be remembered is emotionally evocative and they are allowed to process it as such.     

Conjunction errors in recognition memory: modality-free errors for older adults but not for young adults

A dual-process theory of memory was applied to processes in normal aging, with a focus on recognition errors in the feature-conjunction paradigm (i.e., false recognition of blackbird after studying parent words blackmail and/or jailbird). Study repetition was manipulated so that some parent words occurred once and others occurred three times. Age-related differences on hit scores occurred for two experiments. The results for feature and conjunction conditions showed repetition effects but no age-related differences when participants were uninformed of the lures (Experiment 1). However, age-related differences emerged when the retrieval of modality source information created a way to evade conjunction errors (Experiment 2). In the second experiment, study repetition decreased errors for the young adults but increased errors for the older adults, and young adults were better able than older adults to avoid conjunction errors when the parent words had been repeated. For older adults, the conjunction errors were modality-free. The results provide additional evidence that older adults experience difficulty in recollecting aspects of a study experience, and the results from groups of young adults required to respond quickly on the tests provide converging evidence for this conclusion.     

Direct and indirect tests of memory for category exemplars in young and older adults

Young and older adults were compared on direct (cued recall) and indirect (exemplar generation) tests of memory for category members. Because category names served as cues in both tasks, amount of retrieval support was constant across tasks. Although older adults produced fewer category members in cued recall, priming of category exemplars in the generation task did not vary with age. These results suggest that age constancy in priming tasks does not depend on physical similarity between study materials and retrieval cues provided at test and point to the importance of deliberate recollection as a factor in determining the extent of age differences in memory.     

Direct and indirect measures of memory for modality in young and older adults.

In 2 experiments, young and older adults demonstrated modality effects of similar magnitude in perceptual identification tasks. That is, both young and older adults demonstrated more repetition priming when study and test modalities matched than when they were different, suggesting that contextual information was equally available across age. However, when asked explicitly to retrieve modality information, older adults were less accurate than young adults. These results constitute evidence for a dissociation between direct and indirect measures of memory for modality information. They call into question hypotheses that memory impairment in old age is due to deficient encoding of contextual information and challenge current accounts of modality effects in repetition priming.     

The benefits and costs of repeated memory tests for young and older adults

Repeated and prolonged searches of memory can lead to an increase in how much is recalled, but they can also lead to memory errors. These 3 experiments addressed the costs and benefits of repeated and prolonged memory tests for both young and older adults. Participants saw and imagined pictures of objects, some of which were physically or conceptually similar, and then took a series of repeated or prolonged recall tests. Both young and older adults recalled more on later tests than on earlier ones, though the increase was less marked for older adults. In addition, despite recalling less than did young adults, older adults made more similarity-based source misattributions (i.e., claiming an imagined item was seen if it was physically or conceptually similar to a seen item). Similar patterns of fewer benefits and more costs for older adults were seen on both free and forced recall tests and on timed and self-paced tests. Findings are interpreted in terms of age-related differences in binding processes.     

Medial prefrontal cortex and hippocampal activity differentially contribute to ordinal and temporal context retrieval during sequence memory

Remembering sequences of events defines episodic memory, but retrieval can be driven by both ordinality and temporal contexts. Whether these modes of retrieval operate at the same time or not remains unclear. Theoretically, medial prefrontal cortex (mPFC) confers ordinality, while the hippocampus (HC) associates events in gradually changing temporal contexts. Here, we looked for evidence of each with BOLD fMRI in a sequence task that taxes both retrieval modes. To test ordinal modes, items were transferred between sequences but retained their position (e.g., AB3). Ordinal modes activated mPFC, but not HC. To test temporal contexts, we examined items that skipped ahead across lag distances (e.g., ABD). HC, but not mPFC, tracked temporal contexts. There was a mPFC and HC by retrieval mode interaction. These current results suggest that the mPFC and HC are concurrently engaged in different retrieval modes in support of remembering when an event occurred.

Memory for sequences of events is a fundamental component of episodic memory (Tulving 1984, 2002; Allen and Fortin 2013; Howard and Eichenbaum 2013; Eichenbaum 2017). While different experiences share overlapping elements, the sequence of events is unique. Remembering the order of events allows us to disambiguate episodes with similar content and make detailed predictions supporting decision-making.At least two complementary memory processes contribute to the retrieval of events in the correct sequence: ordinal (Orlov et al. 2002) and temporal context (Howard and Kahana 2002) retrieval modes. Whether these disparate retrieval modes operate coincidently or not remains an open question with consequences for understanding basic mechanisms of how we remember the events that unfold throughout our day. According to an ordinal retrieval mode, items are remembered by their position within an event sequence (DuBrow and Davachi 2013; Allen et al. 2014; Long and Kahana 2019), providing sequential memory through well-established semantic or abstracted relationships (first, second, third, etc.). While for a temporal context retrieval mode, events are remembered through a gradually changing temporal context within which specific items have been associated. According to temporal contexts, when an element of a sequence is presented or retrieved (e.g., “C” in ABCDEF), items that are more proximal in the sequence (e.g., the “D” in the sequence) have a higher retrieval rate compared with items that are further away (e.g., the “F” in the sequence). These temporal contexts result from item associations that are dependent on time varying neural activity (e.g., Eichenbaum 2014), and contribute to sequence memory through the reactivation of neighboring items during retrieval (DuBrow and Davachi 2013; Long and Kahana 2019).The medial prefrontal cortex (mPFC) and hippocampus (HC) are thought to contribute to sequence memory through ordinal representations and temporal contexts, respectively (Agster et al. 2002; Fortin et al. 2002; Kesner et al. 2002; DeVito and Eichenbaum 2011; Allen et al. 2016; Jenkins and Ranganath 2016). In rodents, mPFC disruptions impair sequence memory (DeVito and Eichenbaum 2011; Jayachandran et al. 2019), mPFC “time cells” are evident (Tiganj et al. 2017), and positions within a sequence can be the main determinant of differential activity in mPFC neurons during spatial sequences (Euston and McNaughton 2006). In humans, mPFC activation is sensitive to temporal order memory (Preston and Eichenbaum 2013), and codes for information about temporal positions within image sequences regardless of the image itself (Hsieh and Ranganath 2015). HC activations are also generally associated with temporal order memory (Kumaran and Maguire 2006; Ekstrom and Bookheimer 2007; Lehn et al. 2009; Ross et al. 2009; Jenkins and Ranganath 2010; Tubridy and Davachi 2011; Kalm et al. 2013; Hsieh et al. 2014; Goyal et al. 2018). Prior evidence further shows that the medial temporal lobe, specifically the HC formation, plays a critical role in the use of a TCM retrieval mode in the brain (Manns et al. 2007; Hsieh et al. 2014; Bladon et al. 2019). The HC binds events within temporal contexts (Eichenbaum et al. 2007; DuBrow and Davachi 2013; Bladon et al. 2019) through a gradually changing neural context (Manns et al. 2007; Mankin et al. 2012). Similarly, medial temporal lobe neuronal and BOLD activations in humans have demonstrated evidence for gradually evolving temporal contexts (Howard et al. 2012; Kalm et al. 2013; Kragel et al. 2015).Here we tested the contributions of the mPFC and HC during a visual sequence memory task that provides behavioral evidence of both ordinal and temporal context retrieval modes (see Fig. 1A; task modified from Allen et al. 2014). Briefly, participants first memorized six visual sequences (six images each) in a single passive viewing phase, and then were instructed to make judgments as to whether individual items were subsequently presented in sequence (InSeq) or out of sequence (OutSeq) over 240 self-paced presentations of each of the six items from each sequence. In the task, the two retrieval modes are parsed using probe trials that place conflicting demands on ordinal (Orlov et al. 2000; Allen et al. 2014, 2015) and temporal context modes (Jayachandran et al. 2019). We first evaluated ordinal retrieval modes using items that were transferred from one sequence to another while retaining their ordinal position (Ordinal Transfers) (Fig. 1B). Evidence for an ordinal-based retrieval mode occurs when these probes are identified as in sequence, because they occur in the same ordinal position as their original sequence. mPFC activations (but not HC) was strongest for these ordinal retrievals. Second, we evaluated a temporal context retrieval mode using items that skipped ahead (Skips) (Fig. 1B) with shorter lag distances (ABCFEF) compared with larger lag distances (AFCDEF). Skips should be most difficult to detect on the shortest lag distances because proximal items in a sequence are more likely to be retrieved (Howard and Kahana 2002; Kragel et al. 2015) and thus judged as InSeq. HC activations (but not mPFC) tracked with lag distance, providing evidence the HC is more reflective of a temporal context-based retrieval mode. Importantly, a significant interaction was observed such that mPFC and HC differentially activated for ordinal and temporal context retrievals. Altogether, our data show that sequence memory involves both retrieval modes. In line with these results, we suggest that understanding episodic memory requires more insight into the neurobiology of ordinal processing, in addition to the more often studied temporal contexts, in the mPFC and HC system.Open in a separate windowFigure 1.Sequence memory task and overall performance levels. Participants were tested on a sequence memory task that differentially burdens different retrieval modes using different out of sequence probe trial types. (A) An example sequence set that included six sequences. Two sequences were low memory demand sequences and four were high memory demand sequences. (B) There were three out of sequence probe trial types: items that were repeated in the sequence (Repeats), items that were presented too early in the sequence (Skips), and items that transferred from one sequence to another, while remaining in their ordinal position (Ordinal Transfers). Repeats and Skips occurred throughout the whole task, whereas Ordinal Transfers occurred during the second half only. (C) Accuracy throughout the task (error bars = ±1SD). Participants performed best on Repeats, then Skips, and poorest on Ordinal Transfers. (D,E) Distributions of response times for all InSeq trials (D, gray bars) and for all OutSeq trials (E, gray bars) for all participants with a fitted two-term Gaussian curve (black line). (F) A bimodal Gaussian curve fit better than a unimodal curve for InSeq and OutSeq trials. A trimodal curve did not improve the fit and increased the root mean squared error (not shown), suggesting distinct decisions decision-making between two decisions. It was rare to observe responses outside of the two distributions.     

The effect of verbal elaborations on memory in young and older adults

The Stein paradigm was used to examine the circumstances under which verbal elaborations enhance memory in young and older adults. Subjects studied target adjectives that were embedded in one of three sentence contexts that varied in elaboration of the subject-adjective relationship: (1) nonelaborated base sentences; (2) base sentences with semantically consistent, but arbitrary verbal, elaborations; and (3) base sentences with explanatory verbal elaborations that clarified the significance of the subject-adjective relationship. The presence of the elaborations was varied at encoding and retrieval, and cued recall of the target adjectives was tested with incidental and intentional learning procedures. In Experiments 1A and 1B, explanatory elaborations at encoding and retrieval yielded the largest memorial facilitation for both young and older adults, and the benefit was comparable for the incidental and intentional learning measures. In Experiment 2, age-related differences in recall were minimal with explanatory elaborations at encoding and retrieval, but larger age differences occurred in the nonelaborated comparison conditions. In Experiment 3, explanatory elaborations present at encoding but not at retrieval enhanced recall when the original Stein stimuli were used, but not with the present stimuli. The implications of these results with regard to the mnemonic efficacy of verbal elaborations for young and older adults are discussed.