The neural correlates of updating information in verbal working memory

The aim of the present study was to re-examine cerebral areas subserving the updating function of the central executive with a running span task requiring subjects to watch strings of consonants of unknown length and then to recall serially a specific number of recent items. In order to dissociate more precisely the updating process from the storage function, a four-item instead of a six-item memory load was used, contrary to our previous study (Salmon et al., 1996). In addition, a serial recall procedure was preferred to a recognition procedure in order to suppress the use of visuospatial strategies. The most significant increase of rCBF occurred in the left frontopolar cortex (Brodmann's area 10), spreading to the left middle frontal (Brodmann's area 46). Results suggest that frontopolar activation underlies an updating process in working memory.     

What can we learn about immediate memory from the development of children's free recall?

We ask the question: Which aspects of immediate memory performance improve with age? In two studies, we reexamine the widely held view that primary memory capacity estimates derived from children's immediate free recall are age invariant. This was done by assessing children's immediate free-recall accuracy while also measuring the order in which they elected to recall items (Experiment 1) and by encouraging children to begin free recall with items from towards the end of the presented list (Experiment 2). Across samples aged between 5 and 8 years we replicated the previously reported age-related changes in free-recall serial position functions when aggregated across all trials of the standard task, including an absence of age differences in the recency portion of this curve. However, we also show that this does not reflect the fact that primary memory capacity is constant across age. Instead, when we incorporate order of report information, clear age differences are evident in the recall of list-final items that are output at the start of a participant's response. In addition, the total amount that individuals recalled varied little across different types of free-recall tasks. These findings have clear implications for the use of immediate free recall as a means of providing potential indices of primary memory capacity and in the study of the development of immediate memory.     

Controlled recall of verbal material in temporal lobe epilepsy

This study used a guided process‐dissociation procedure to examine the contribution of controlled and automatic uses of memory to a cued‐recall task in 24 patients with unilateral temporal lobe epilepsy (TLE: 12 left‐sided; 12 right‐sided), and 12 neurotypical controls. In an inclusion task, participants attempted to complete three‐letter word stems using previously studied words, in an exclusion task they aimed to avoid using studied words to complete stems. Patients with left TLE produced fewer target completions under inclusion conditions. Completion rates were not significantly different under exclusion conditions. Estimates derived from process dissociation calculations, confirmed that the cued‐recall deficit in left TLE patients arose entirely from impairment in controlled memory processes. There were no group differences in the estimates of automatic processes. Recognition judgements of stems corresponding to studied words did not differ between the groups. Overall the results support the view that controlled and automatic memory processes are mediated by separable neural systems. Hippocampal and related structures within the left MTL are more important than corresponding right hemisphere structures for the controlled retrieval of verbal material. In contrast, the findings from this study do not suggest that the left and right temporal lobes make a differential contribution to automatic memory processing. The theoretical and clinical relevance of these findings are discussed.     

Do updating tasks involve updating? Evidence from comparisons with immediate serial recall

Updating tasks require participants to process a sequence of items, varying in length, and afterwards to remember only a fixed number of the elements of the sequence; the assumption being that participants actively update the to-be-recalled list as presentation progresses. However recent evidence has cast doubt on this assumption, and the present study examined the strategies that participants employ in such tasks by comparing the serial position curves found in verbal and visuo-spatial updating tasks with those seen in standard serial recall tasks. These comparisons showed that even when the same number of items are presented or recalled, participants perform less well in an updating than a serial recall context. In addition, while standard serial position effects were observed for serial recall, marked recency and reduced or absent primacy effects were seen in updating conditions. These findings suggest that participants do not typically adopt a strategy of actively updating the memory list in updating tasks, but instead tend to wait passively until the list ends before trying to recall the most recently presented items.     

Do updating tasks involve updating? Evidence from comparisons with immediate serial recall

Updating tasks require participants to process a sequence of items, varying in length, and afterwards to remember only a fixed number of the elements of the sequence; the assumption being that participants actively update the to-be-recalled list as presentation progresses. However recent evidence has cast doubt on this assumption, and the present study examined the strategies that participants employ in such tasks by comparing the serial position curves found in verbal and visuo-spatial updating tasks with those seen in standard serial recall tasks. These comparisons showed that even when the same number of items are presented or recalled, participants perform less well in an updating than a serial recall context. In addition, while standard serial position effects were observed for serial recall, marked recency and reduced or absent primacy effects were seen in updating conditions. These findings suggest that participants do not typically adopt a strategy of actively updating the memory list in updating tasks, but instead tend to wait passively until the list ends before trying to recall the most recently presented items.     

Updating in working memory: a comparison of good and poor comprehenders

In this research, we examined the relation between reading comprehension and success in a working memory updating task. We tested the hypotheses that poor comprehenders' deficiencies are associated with a specific difficulty in the working memory updating process, particularly in controlling for information that is no longer relevant. In the first experiment, groups of poor and good comprehenders, ages 8-11 years, were administered a working memory updating task. In the second experiment a year later, a subgroup of participants involved in the first experiment was tested with a different updating task. In both experiments, poor comprehenders had less accurate recall performance and made more intrusion errors than did good comprehenders. Moreover, distinguishing intrusion errors on the basis of their permanence in memory, we found that poor comprehenders were more likely to intrude items that were maintained longer in memory than were good comprehenders. This type of error predicted reading comprehension abilities better than did working memory recall. This suggests that the relation between reading comprehension and working memory is mediated by the ability to control for irrelevant information.     

Effects of Motivation on Young Children's Object Recall and Strategy Use

The study was designed to examine the effects of motivation on young children's recall for object names and early-emerging mnemonic activities. Seventy-two 4-year-old children were randomly assigned to 1 of 3 instructional conditions: incidental, intentional, or motivational. Each child was shown 10 small toy objects and provided a 90 s study period prior to recall. The children's mnemonic behaviors were videotaped for subsequent coding. The children in the incidental condition were instructed to simply look at the toys while children in the intentional and motivational condition were given explicit instructions to remember. The motivational group was also told that they could keep whichever toys they remembered. A recognition memory task was employed to examine the extent to which the stimuli were encoded during the study period. The children's recall memory did not vary as a function of instructional condition. Children's use of singular versus multiple strategies was calculated, along with a weighted summary score giving most weight to the participant's use of mature mnemonic strategies. Significant differences in strategy use were found, favoring the motivational condition. Significant positive correlations were found between the weighted summary scores and object recall, and the teacher ratings of mastery motivation and object recall. Mastery motivation was found to be unrelated to the strategic summary scores, failing to mediate strategic behaviors. The results suggest that when providing incentives to remember, children apparently engaged in more effortful mnemonic processing in order to remember the items, even though a greater number of items were not recalled.     

Updating memory using mnemonic devices

The process of memory updating enables people to recall information most recently associated with a particular stimulus context and to ignore or forget information previously associated with it. In a series of five experiments utilizing mnemonic devices it was found that when associative interference was maximized, only a limited disruption of updating resulted. In addition, mnemonic recall was not dependent on the utilization of higher-order memory components. However, support was found for the hypothesis that memory can be searched using temporal cues and for the idea that the size of the search set formed in memory is important. It was found that the older the event was to be recalled, the greater were the number of events in the search set and therefore the greater was the magnitude of the recall error. The size of the search set created in memory and the role of temporal-contextual cues in defining this search set may be important factors not only in mnemonic recall but in other types of learning and recall as well.     

Developmental differences in recall and recognition: The relationship between rehearsal and memory as test expectation changes

An overt rehearsal procedure was used to study the relationship between children's rehearsal strategies and their memory performance under different conditions of test expectation. Previous work has shown that developmental differences in rehearsal content affect recall performance. This study was designed to address the question of why active rehearsal content results in superior recall performance. The equivalence of recognition-memory performance for third- (age 9) and sixthgraders (age 12) suggests that developmental differences in recall are due to the effects of rehearsal content on item retrieval from permanent memory. In addition, the data indicate that third- and sixth-graders can differentiate between expected recall and recognition tests and, with the exception of the sixth-grade boys, use this information to modify their rehearsal content. These differences in rehearsal content, as a function of the type of test expected, corresponded to changes in recall performance.     

The influence of theta transcranial alternating current stimulation (tACS) on working memory storage and processing functions

The study aimed to explore the role of the fronto-parietal brain network in working memory function—in temporary storage and manipulation of information. In a single blind sham controlled experiment 36 respondents solved different working memory tasks after theta transcranial alternating current stimulation (tACS) was applied to left frontal, left parietal and right parietal areas. Both verum tACS protocols stimulating parietal brain areas (target electrodes positioned at location P3, or P4) had a positive effect on WM storage capacity as compared with sham tACS, whereas no such influence was observed for the stimulation of the left frontal area (target electrode positioned at location F3). A second finding was that left parietal theta tACS had a more pronounced influence on backward recall than on forward recall, which was not related to task content (spatial or verbal). The influence of theta tACS on WM executive processes was most pronounced for right parietal stimulation. The results are discussed in the broad theoretical framework of the multicomponent model of working memory.     

The effects of “effort after meaning” on recall: Differences in within- and between-subjects designs

In four experiments, we examined free recall of ambiguous sentences with or without corresponding cues to facilitate comprehension, using Auble and Franks’s (1978) paradigm to examine effort after meaning (Bartlett, 1932). The ambiguous sentences were studied without cues, with cues meaningfully embedded in them, with cues provided shortly before the sentence (precue), or with cues following the sentence after several seconds (delayed cue). When these conditions were manipulated within subjects, the process of cue integration in the pre- and delayed-cue conditions enhanced recall, relative to the no-cue and embedded-cue conditions. Furthermore, in a test condition in which subjects first attempted to recall the cues alone, recall was also best in the delayed-cue condition. The effects described above did not occur when the cue presentation conditions varied between subjects, and on a test of order reconstruction, there was even an advantage for sentences studied in the embedded-cue condition over those studied in the delayed-cue condition. The dissociative effects of experimental design on sentence recall and order reconstruction suggest that effort after meaning might enhance memory for study items at the cost of impairing memory for temporal order information.     

Hemispheric asymmetries in auditory distraction

Serial-verbal short-term memory is impaired by irrelevant sound, particularly when the sound changes acoustically (the changing-state effect). In contrast, short-term recall of semantic information is impaired only by the semanticity of irrelevant speech, particularly when it is semantically related to the target memory items (the between-sequence semantic similarity effect). Previous research indicates that the changing-state effect is larger when the sound is presented to the left ear in comparison to the right ear, the left ear disadvantage. In this paper, we report a novel finding whereby the between-sequence semantic similarity effect is larger when the irrelevant speech is presented to the right ear in comparison to the left ear, but this right ear disadvantage is found only when meaning is the basis of recall (Experiments 1 and 3), not when order is the basis of recall (Experiment 2). Our results complement previous research on hemispheric asymmetry effects in cross-modal auditory distraction by demonstrating a role for the left hemisphere in semantic auditory distraction.     

Bartlett Revisited: Reconfiguration of Long-Term Memory in Young and Older Adults

This study was performed after the tradition of F. C. Bartlett (1932), who demonstrated that memory reconfigures over time. The authors investigated the memory of young and older adults to examine the degree to which the aging process influences reconfigurative tendencies. From an initial sample of 53 participants, 20 young and 19 older adults completed 6 tests of recall for Bartlett's original text materials over an 84-day period. Consistent with the broad conclusions of Bartlett's study, reconfiguration was observed: Both young and older adults introduced errors into memory. Older adult recall was lower overall than that of young adults, and recall performance diminished over time. However, there was no difference between the performances of young and older adults with respect to incorrectly recalled intrusive elements.     

The role of working memory and updating in Coloured Raven Matrices performance in typically developing children

A large body of evidence indicates that working memory correlates with performance on fluid intelligence tasks such as Raven's tests. However, light still needs to be shed on which particular aspects of working memory might be most critically related to fluid intelligence, and whether working memory updating—which appears crucial to intellectual functioning—has a prominent role. To address these issues more closely, our study presented participants (aged 5–11 years) with the Raven's Coloured Progressive Matrices, an updating task, and a battery of working memory tasks. Our findings confirm that working memory indeed plays an important part in explaining fluid intelligence, in particular that updating information in working memory is critical to fluid intelligence in the context of development.     

Walking through doorways causes forgetting: recall

The aim of the current study was to explore how the location updating effect is affected when people are tested using recall rather than recognition, which is what has been done in prior work. Differences in the memory processes involved with these two tasks lead to predictions for two different patterns of data. In Experiment 1, memory was tested by having participants recall the single object they were carrying or had just put down, whereas in Experiment 2, people sometimes needed to recall both objects. It was found that, unlike recognition test performance, a similar location updating effect was found for both Associated (what was currently being carried) and Dissociated (what was recently set down) objects. Moreover, when both objects were correctly recalled, there was a bias to remember them in the order that they were encountered. Finally, if only one object was correctly recalled, it was the Associated object that was currently being carried. Overall, these results are consistent with the Event Horizon Model of event cognition.     

Binding and content updating in working memory tasks

Working memory updating can involve processing of either a specific memory content or a binding. So far, research has focused mainly on single contents as objects of updating, via recall accuracy measures. Here, we have addressed more direct measurement of the updating process (i.e., response times), assessing individually the role of single contents, as well as bindings. To this end, we compared two updating tasks from separate research traditions: a RT‐based computer task and a classical accuracy‐based task. The former consisted of trials where measures of content and binding updating were obtained, allowing a dissociation between these two components. The latter measured recall accuracy and intrusion rate for lists of words under different conditions of maintenance/inhibition. These results enable a better understanding of the updating process for the dual components of binding and content updating, and their potential role in an accuracy‐based task. An overlap between the underlying components of updating tasks was demonstrated, specifically between binding updating RT and intrusion rate. Notably, binding updating appears to be a more sensitive measure in explaining results in the classical updating task.     

Serial-position effects for items and relations in short-term memory

Two experiments used immediate probed recall of words to investigate serial-position effects. Item memory was tested through probing with a semantic category. Relation memory was tested through probing with the word's spatial location of presentation. Input order and output order were deconfounded by presenting and probing items in different orders. Primacy and recency effects over input position were found for both item memory and relation memory. Both item and relation memory declined over output position. The finding of a U-shaped input position function for item memory rules out an explanation purely in terms of positional confusions (e.g., edge effects). Either these serial-position effects arise from variations in the intrinsic memory strength of the items, or they arise from variations in the strength of item–position bindings, together with retrieval by scanning.     

Direct retrieval from elaborated memory traces

Four experiments were performed to investigate the beneficial effects of elaborative processing on recall performance. Specifically, the experiments investigated J. R. Anderson's (1983) claim that increasing the number of associative pathways between propositions in a memory trace improves recall performance through direct retrieval. In this study, procedures were used that allowed the amount of elaboration to be systematically varied while the use of inferential reconstruction to aid recall was eliminated, thus providing a test of J. R. Anderson's model. Across all experiments, the results showed that recall of a name was better when it had been stored in a less elaborated memory trace. The results suggest that when reconstructive processes are eliminated, elaboration decreases rather than increases recall performance.     

Remaking memories: reconsolidation updates positively motivated spatial memory in rats

There is strong evidence that reactivation of a memory returns it to a labile state, initiating a restabilization process termed reconsolidation, which allows for updating of the memory. In this study we investigated reactivation-dependent updating using a new positively motivated spatial task in rodents that was designed specifically to model a human list-learning paradigm. On Day 1, rats were trained to run to three feeders (List 1) for rewards. On Day 2, rats were trained to run to three different feeders (List 2) in either the same (Reminder condition) or a different (No Reminder condition) experimental context than on Day 1. On Day 3, rats were cued to recall List 1. Rats in the Reminder condition made significantly more visits to List 2 feeders (intrusions) during List 1 recall than rats in the No Reminder condition, indicating that the reminder triggered reactivation and allowed integration of List 2 items into List 1. This reminder effect was selective for the reactivated List 1 memory, as no intrusions occurred when List 2 was recalled on Day 3. No intrusions occurred when retrieval took place in a different context from the one used at encoding, indicating that the expression of the updated memory is dependent upon the retrieval context. Finally, the level of intrusions was highest when retrieval took place immediately after List 2 learning, and generally declined when retrieval occurred 1-4 h later, indicating that the List 2 memory competed with short-term retrieval of List 1. These results demonstrate the dynamic nature of memory over time and the impact of environmental context at different stages of memory processing.     

The Contribution of Executive Function to Source Memory Development in Early Childhood

Age-related differences in episodic memory judgments assessing recall of fact information and the source of this information were examined. The role of executive function (EF) in supporting early episodic memory ability was also explored. Four- and 6-year-old children were taught 10 novel facts from two different sources (experimenter or puppet), and memory for both fact and source information was later tested. Measures of working memory, inhibitory control, and set shifting were obtained to produce an indicator of children's EF. Six-year-olds recalled more fact and source information than did 4-year-olds. Regression analyses revealed that age, language ability, and EF accounted for unique variance in children's fact recall and source recall performance. These findings suggest a link between episodic memory and EF, and we propose that developmental investigations should further explore this association.