Memory at Play: Examining Relations Between Episodic and Semantic Memory in a Children's Museum.

The relation between episodic and semantic memory was examined by testing how semantic knowledge influences children's episodic memory for events and their locations. Five-, six-, and seven-year-olds (N = 87) engaged in events in a children's museum designed as a town. Events were semantically congruent or incongruent with the spatial location (e.g., sorting mail at post office vs. grocery store). In addition to this experimental paradigm, a semantic interview assessed children's semantic knowledge about real-world locations. Accuracy in the experimental paradigm showed that children's semantic memory influenced memory for locations. Interviews revealed age-related improvements in children's semantic knowledge. Regression analyses examined factors that best supported episodic memory. These results provide novel insights and highlight the utility of research in naturalistic settings.

Semantic memory before episodic memory: How memory research can inform knowledge and belief representations.

Knowledge and belief attribution are discussed in the context of episodic and semantic memory theory and research, with reference to patient-lesion and developmental studies under naturalistic conditions. Consideration of how episodic and semantic memory relate to each other and intersect in the real world, including how they fail, can illuminate the approach to studying how people represent others' minds.

Neural correlates of autobiographical memory retrieval in children and adults.

Autobiographical memory (AM) is a critically important form of memory for life events that undergoes substantial developmental changes from childhood to adulthood. Relatively little is known regarding the functional neural correlates of AM retrieval in children as assessed with fMRI, and how they may differ from adults. We investigated this question with 14 children ages 8-11 years and 14 adults ages 19-30 years, contrasting AM retrieval with semantic memory (SM) retrieval. During scanning, participants were cued by verbal prompts to retrieve previously selected recent AMs or to verify semantic properties of words. As predicted, both groups showed AM retrieval-related increased activation in regions implicated in prior studies, including bilateral hippocampus, and prefrontal, posterior cingulate, and parietal cortices. Adults showed greater activation in the hippocampal/parahippocampal region as well as prefrontal and parietal cortex, relative to children; age-related differences were most prominent in the first 8 sec versus the second 8 sec of AM retrieval and when AM retrieval was contrasted with semantic retrieval. This study is the first to characterise similarities and differences during AM retrieval in children and adults using fMRI.

More to it than meets the eye: how eye movements can elucidate the development of episodic memory.

The ability to recognise past events along with the contexts in which they occurred is a hallmark of episodic memory, a critical capacity. Eye movements have been shown to track veridical memory for the associations between events and their contexts (relational binding). Such eye-movement effects emerge several seconds before, or in the absence of, explicit response, and are linked to the integrity and function of the hippocampus. Drawing from research from infancy through late childhood, and by comparing to investigations from typical adults, patient populations, and animal models, it seems increasingly clear that eye movements reflect item-item, item-temporal, and item-spatial associations in developmental populations. We analyse this line of work, identify missing pieces in the literature and outline future avenues of research, in order to help elucidate the development of episodic memory.

Structural development of the hippocampus and episodic memory: developmental differences along the anterior/posterior axis.

The hippocampus is critically involved in episodic memory, yet relatively little is known about how the development of this structure contributes to the development of episodic memory during middle to late childhood. Previous research has inconsistently reported associations between hippocampal volume and episodic memory performance during this period. We argue that this inconsistency may be due to assessing the hippocampus as a whole, and propose to examine associations separately for subregions along the longitudinal axis of the hippocampus. In the present study, we examined age-related differences in volumes of the hippocampal head, body, and tail, and collected episodic memory measures in children ages 8-11 years and young adults (N = 62). We found that adults had a smaller right hippocampal head, larger hippocampal body bilaterally, and smaller right hippocampal tail compared with children. In adults, but not in children, better episodic memory performance was associated with smaller right hippocampal head and larger hippocampal body. In children, but not in adults, better episodic memory was associated with larger left hippocampal tail. Overall, the results suggest that protracted development of hippocampal subregions contribute to age-related differences in episodic memory.

The eyes know time: a novel paradigm to reveal the development of temporal memory.

Temporal memory in 7-year-olds, 10-year-olds, and young adults (N = 78) was examined introducing a novel eye-movement paradigm. Participants learned object sequences and were tested under three conditions: temporal order, temporal context, and recognition. Age-related improvements in accuracy were found across conditions; accuracy in the temporal conditions was correlated with conventional time knowledge. Eye movements tracked the veridicality of temporal order memory in adults and 10-year-olds seconds before providing memory judgments, suggesting that these movements reflect implicit access to temporal information. Seven-year-olds overall did not show this eye-movement effect, but those who did were more accurate than those who did not. Results suggest that eye movements capture aspects of temporal memory development that precede overt decision processes-with implications for hippocampal development.

The convergence of naturalistic paradigms and cognitive neuroscience methods to investigate memory and its development.

Studies that involve lab-based stimuli (e.g., words, pictures) are fundamental in the memory literature. At the same time, there is growing acknowledgment that memory processes assessed in the lab may not be analogous to how memory operates in the real world. Naturalistic paradigms can bridge this gap and over the decades a growing proportion of memory research has involved more naturalistic events. However, there is significant variation in the types of naturalistic studies used to study memory and its development, each with various advantages and limitations. Further, there are notable gaps in how often different types of naturalistic approaches have been combined with cognitive neuroscience methods (e.g., fMRI, EEG) to elucidate the neural processes and substrates involved in memory encoding and retrieval in the real world. Here we summarize and discuss what we identify as progressively more naturalistic methodologies used in the memory literature (movie, virtual reality, staged-events inside and outside of the lab, photo-taking, and naturally occurring event studies). Our goal is to describe each approach's benefits (e.g., naturalistic quality, feasibility), limitations (e.g., viability of neuroimaging method for event encoding versus event retrieval), and discuss possible future directions with each approach. We focus on child studies, when available, but also highlight past adult studies. Although there is a growing body of child memory research, naturalistic approaches combined with cognitive neuroscience methodologies in this domain remain sparse. Overall, this viewpoint article reviews how we can study memory through the lens of developmental cognitive neuroscience, while utilizing naturalistic and real-world events.

Children's and adults' memory for the order of events in a museum: A preliminary study about temporal memory and its development using photo-taking and event-related potentials.

Remembering personal past events and their order is important. These capacities are essential to episodic and autobiographical memory theories, are needed in the creation of life stories and vital in forensic settings. As important as memory for events and their order are, relatively little is known about their development and the underlying neural processes that support them. Further, there is a paucity of studies that have examined memory and its development for autobiographical, yet controlled, events. The objective of this study was to examine memory for the temporal order of naturalistic "real world" events by directly comparing 7-11-year-olds and adults using both behavioral and event-related potential (ERP) measures. Participants photographed events at a local museum and after a delay, we used their photographs to test their memory for the temporal order of pairs of the events. We experimentally manipulated the temporal distance between the event pairs (whether the two events photographed in the pair had a short or long temporal distance between them). A memory asymmetry manipulation was also included such that at retrieval, photographs were either presented in forward direction (photograph on the top configuration was taken before photograph shown on the bottom) or vice versa. Children and adults showed sensitivity to temporal distance between events based on behavior (in some instances accuracy was higher for long compared to short temporal distance) and ERP (differential neural processing for short and long temporal distance conditions). Only adults showed sensitivity to the memory asymmetry manipulation, and only when the events occurred within a short temporal distance. A larger study is needed to confirm the present "proof of concept" study results. There is strong potential of this photo paradigm approach, combining naturalistic events with ERP, in future developmental studies, and would further our understanding of how memory behavior and the neural processes underlying memory operate in the "real world."

Beyond initial encoding: measures of the post-encoding status of memory traces predict long-term recall during infancy.

The first years of life are witness to rapid changes in long-term recall ability. In the current research we contributed to an explanation of the changes by testing the absolute and relative contributions to long-term recall of encoding and post-encoding processes. Using elicited imitation, we sampled the status of 16-, 20-, and 24-month-old infants' memory representations at various time points after experience of events. In Experiment 1, infants were tested immediately, 1 week after encoding, and again after 1 month. The measure of 1-week trace status was a unique predictor of 1-month delayed recall. In Experiment 2, infants were tested immediately, 15 min, 48 h, and 2 weeks after encoding and again 1 month later. The measures of 15-min and 48-h trace strength contributed unique variance in 1-month delayed recall. The findings highlight the need to consider post-encoding processes in explanations of variability in long-term memory during infancy.

Bringing order to life events: memory for the temporal order of autobiographical events over an extended period in school-aged children and adults.

Remembering temporal information associated with personal past events is critical. Yet little is known about the development of temporal order memory for naturally occurring events. In the current research, 8- to 10-year-old children and adults took photographs daily for 4 weeks. Later, they participated in a primacy/recency task (were shown 2 of their photographs and decided which event occurred first) and an ordering task (ordered 12 photographs taken over the 4-week period). All participants showed above-chance performance in primacy/recency; adults were more accurate than children. For ordering, children and adults showed similar patterns and performance was relatively low. This study has implications for autobiographical memory theories and suggests that ordering accuracy might not be necessary for adult-like autobiographical memory. Practical and legal implications of the findings also are discussed.

Children's memory "in the wild": examining the temporal organization of free recall from a week-long camp at a local zoo.

Free-recall paradigms have greatly influenced our understanding of memory. The majority of this research involves laboratory-based events (e.g., word lists) that are studied and tested within minutes. This literature shows that adults recall events in a temporally organized way, with successive responses often coming from neighboring list positions (i.e., temporal clustering) and with enhanced memorability of items from the end of a list (i.e., recency). Temporal clustering effects are so robust that temporal organization is described as a fundamental memory property. Yet relatively little is known about the development of this temporal structure across childhood, and even less about children's memory search for real-world events occurring over an extended period. In the present work, children (N = 144; 3 age groups: 4-5-year-olds, 6-7-year-olds, 8-10-year-olds) took part in a 5-day summer camp at a local zoo. The camp involved various dynamic events, including daily animal exhibit visits. On day 5, children were asked to recall all the animals they visited. We found that overall recall performance, in terms of number of animals recalled, improved steadily across childhood. Temporal organization and recency effects showed different developmental patterns. Temporal clustering was evident in the response sequences for all age groups and became progressively stronger across childhood. In contrast, the recency advantage, when characterized as a proportion of total responses, was stable across age groups. Thus, recall dynamics in early childhood parallel that seen in adulthood, with continued development of temporal organization across middle to late childhood.

It's all about location, location, location: children's memory for the "where" of personally experienced events.

Episodic memory is defined as the ability to recall specific past events located in a particular time and place. Over the preschool and into the school years, there are clear developmental changes in memory for when events took place. In contrast, little is known about developmental changes in memory for where events were experienced. In the current research, we tested 4-, 6-, and 8-year-old children's memories for specific laboratory events, each of which was experienced in a unique location. We also tested the children's memories for the conjunction of the events and their locations. Age-related differences were observed in all three types of memory (event, location, and conjunction of event and location), with the most pronounced differences being in memory for conjunctions of events and their locations. The results have implications for our understanding of the development of episodic memory, including suggestions of protracted development of the ability to contextualize events in their spatial locations.

A "snapshot" of declarative memory: Differing developmental trajectories in episodic and autobiographical memory.

Episodic and autobiographical memory are clearly related, yet in both the adult and developmental literatures it is difficult to compare them because of differences in how the constructs are assessed, including differences in content, levels of control, and time since experience. To address these issues, we directly compared children's and adults' autobiographical and episodic memory using the same controlled paradigm. Participants engaged in a photo-taking activity in a museum (autobiographical encoding) and viewed others' photographs of the same museum exhibits (episodic encoding). At test, participants classified photos as ones they took, viewed, or novel. In the autobiographical condition older children and adults performed similarly; younger children's performance was lower than adults'. In contrast, in the episodic condition both groups of children performed more poorly than adults. The findings suggest the developmental primacy of autobiographical relative to episodic memory, and that traditional episodic tasks may underestimate older children's declarative memory abilities.

Tell Me About Your Visit With the Lions: Eliciting Event Narratives to Examine Children's Memory and Learning During Summer Camp at a Local Zoo.

School-aged children often participate in school field trips, summer camps or visits at informal learning institutions like zoos and museums. However, relatively little is known about children's memory and learning from these experiences, what types of event details and facts are retained, how retention varies across age, and whether different patterns are observed for different types of experiences. We aimed to answer these questions through a partnership with a local zoo. Four- to 10-year-old children (N = 122) participated in a weeklong summer camp, during which they engaged in dynamic events, including visits to zoo animals. On the last day of camp, we elicited autobiographical event narratives for two types of experiences: a child-selected animal event (visit to their favorite animal) and an experimenter-selected animal event. We coded event narratives for length and breadth using previously used autobiographical memory (AM) narrative coding schemes. In addition, we created a coding scheme to examine retention of semantic information (facts). We report the types of autobiographical event details and facts children recalled in their narratives, as well as age group differences that were found to vary depending on the type of information and type of event. Through this naturalistic, yet controlled, study we gain insights into how children remember and learn through hands-on activities and exploration in this engaging and dynamic environment. We discuss how our results provide novel information that can be used by informal learning institutions to promote children's memory and retention of science facts.

Examining the development of memory for temporal context and its underlying neural processes using event-related potentials.

Time is a critical feature of episodic memory-memory for events from a specific time and place (Tulving, 1972). Previous research indicates that temporal memory (memory for 'when') is slower to develop than memory for other details (e.g., 'what' and 'where'), with improvements observed across middle and late childhood. The factors that drive these changes are not yet clear. We used an event-related potential (ERP) recognition memory paradigm to investigate the underlying processes of memory for temporal context in middle to late childhood (7-9-year-olds; 10-12-year-olds) and young adulthood. Behaviorally, we observed age-related improvements in the ability to place events in temporal context. ERP analyses showed old/new effects for children and adults. We also found brain-behavior relations for 1) episodic memory (ERP mean amplitude difference between source hits and correctly identified new trials was correlated to behavioral accuracy), and 2) temporal memory (ERP mean amplitude difference between source hits and source error trials was correlated to accuracy of temporal memory judgments). This work furthers our understanding of the cognitive processes and neural signatures supporting temporal memory development in middle to late childhood, and has implications for episodic memory development more broadly.

Children's Informant Judgments and Recall of Valenced Facts at a Science Center.

In laboratory-based research, children recognize who is an expert and demonstrate an interest in learning from that person. However, children prefer positive information in the moment and sometimes prioritize positivity over expertise. To what extent do these social judgments (e.g., a preference for positivity) relate to information that children remember? We investigated the relation between these judgments and memory at a local science center to better understand children's learning outcomes in naturalistic settings. We examined the extent to which 4- to 8-year-olds accepted facts about an unfamiliar animal from a zookeeper informant (i.e., expert) and a maternal figure (i.e., non-expert) when these facts were positive, negative, or neutral. Children endorsed positive information as correct, regardless of expertise, but demonstrated the strongest memory for neutral information. We discuss the implications of this dissociation for learning outcomes in naturalistic contexts as well as theoretical frameworks regarding children's learning from others.

Longitudinal Development of Memory for Temporal Order in Early to Middle Childhood.

Existing studies examining the development of temporal order memory show that although young children perform above chance on some tasks assessing temporal order memory, there are significant age-related differences across childhood. Yet, the trajectory of children's ability to retrieve temporal order remains unclear as existing conclusions are drawn from cross-sectional studies. The present study utilized an accelerated longitudinal design in order to characterize the developmental trajectory of temporal order memory in a sample of 200 healthy 4- to 8-year-old children. Specifically, two tasks commonly used in the literature were tested longitudinally: a primacy judgment task and an ordering task. Results revealed that, even after controlling for differences in IQ, linearly increasing trajectories characterized age-related change in performance for both tasks; however, change appeared greater for the temporal ordering task. Further, performance on the two tasks was positively related, suggesting shared underlying mechanisms. These findings provide a more thorough understanding of temporal order memory in early to middle childhood by characterizing the developmental trajectories of two commonly used tasks and have important implications for our understanding of children's developing memory more broadly.

Space and time in episodic memory: Effects of linearity and directionality on memory for spatial location and temporal order in children and adults.

Episodic memory is a critical capacity that involves remembering past events along with their spatial and temporal contexts. Relatively little is known about the relations between spatial and temporal information in long-term memory in children or adults. The present research examined the influence of the mental timeline (linear horizontal display extending from the left to right direction for English speakers) on memory for events and their spatial and temporal features in 7-year-olds, 9-year-olds, 11-year-olds and young adults (N = 146). During encoding, participants studied triplets of objects, varying on two dimensions of the mental timeline: linearity (whether objects were presented in linear succession or not) and direction (whether objects were presented from left-to-right or right-to-left). After a delay, during retrieval, participants were tested on their memory for individual objects, and either the spatial location or temporal order of the objects. We found that overall accuracy for spatial location was higher than accuracy for temporal order, and there was a parallel developmental trajectory for both these aspects of memory. Across age groups we found that memory for temporal order, but not spatial location, was influenced by linearity and direction (i.e., match to mental timeline). Thus, in both children and adults the spatiotemporal mental timeline supported memory for temporal order, converging with predictions generated within domains of language and thought and enhancing our understanding of how space and time are represented in the mind.

Eye movements provide an index of veridical memory for temporal order.

The present research examined whether eye movements during retrieval capture the relation between an event and its temporal attributes. In two experiments (N=76), we found converging evidence that eye movements reflected the veridicality of memory for temporal order seconds before overt memory judgments, suggesting that these movements captured indirect access to temporal information. These eye movements did not entirely depend on the amount of contextual cueing available (Experiment 1) and reflected the unique ordinal position of an event in a sequence (Experiment 2). Based on our results, we conclude that eye movements reflected the absolute temporal order of past events.