Asynchronous development of memory integration and differentiation influences temporal memory organization.

Adults remember items with shared contexts as occurring closer in time to one another than those associated with different contexts, even when their objective temporal distance is fixed. Such temporal memory biases are thought to reflect within-event integration and between-event differentiation processes that organize events according to their contextual similarities and differences, respectively. Within-event integration and between-event differentiation are hypothesized to differentially rely on binding and control processes, which may develop at different ages. To test this hypothesis, 5- to 12-year-olds and adults (N = 134) studied quartets of image pairs that contained either the same scene (same-context) or different scenes (different-context). Participants remembered same-context items as occurring closer in time by older childhood (7-9 years), whereas different-context items were remembered as occurring farther apart by early adolescence (10-12 years). The differential emergence of these temporal memory biases suggests within-event integration and between-event differentiation emerge at different ages. RESEARCH HIGHLIGHTS: Children are less likely than adults to use contextual information (e.g., location) to organize their continuous experience in memory, as indicated by temporal memory biases. Biases reflecting within-event integration (i.e., remembering elements with a shared context as occurring closer together in time) emerged in late childhood. Biases reflecting between-event differentiation (i.e., remembering elements from different contexts as occurring farther apart in time) emerged in early adolescence. The differential emergence of biases reflecting within-event integration and between-event differentiation suggests they are distinct, yet complementary, processes that support developmental improvements in event memory organization.

Developmental differences in temporal schema acquisition impact reasoning decisions.

Schemas capture patterns across multiple experiences, accumulating information about common event structures that guide decision making in new contexts. Schemas are an important principle of leading theories of cognitive development; yet, we know little about how children and adolescents form schemas and use schematic knowledge to guide decisions. Here, we show that the ability to acquire schematic knowledge based on the temporal regularities of events increases during childhood and adolescence. Furthermore, we show that temporally mediated schematic knowledge biases reasoning decisions in an age-dependent manner. Participants with greater temporal schematic knowledge were more likely to infer that temporally related items shared other, non-temporal properties, with adults showing the greatest relationship between schema knowledge and reasoning choices. These data indicate that the mechanisms underlying schema formation and expression are not fully developed until adulthood and may reflect the ongoing maturation of hippocampus and prefrontal cortex through adolescence.

Coding Locations Relative to One or Many Landmarks in Childhood.

Cognitive development studies how information processing in the brain changes over the course of development. A key part of this question is how information is represented and stored in memory. This study examined allocentric (world-based) spatial memory, an important cognitive tool for planning routes and interacting with the space around us. This is typically theorized to use multiple landmarks all at once whenever it operates. In contrast, here we show that allocentric spatial memory frequently operates over a limited spatial window, much less than the full proximal scene, for children between 3.5 and 8.5 years old. The use of multiple landmarks increases gradually with age. Participants were asked to point to a remembered target location after a change of view in immersive virtual reality. A k-fold cross-validation model-comparison selected a model where young children usually use the target location's vector to the single nearest landmark and rarely take advantage of the vectors to other nearby landmarks. The comparison models, which attempt to explain the errors as generic forms of noise rather than encoding to a single spatial cue, did not capture the distribution of responses as well. Parameter fits of this new single- versus multi-cue model are also easily interpretable and related to other variables of interest in development (age, executive function). Based on this, we theorize that spatial memory in humans develops through three advancing levels (but not strict stages): most likely to encode locations egocentrically (relative to the self), then allocentrically (relative to the world) but using only one landmark, and finally, most likely to encode locations relative to multiple parts of the scene.

Development of allocentric spatial recall from new viewpoints in virtual reality.

Using landmarks and other scene features to recall locations from new viewpoints is a critical skill in spatial cognition. In an immersive virtual reality task, we asked children 3.5-4.5 years old to remember the location of a target using various cues. On some trials they could use information from their own self-motion. On some trials they could use a view match. In the very hardest kind of trial, they were 'teleported' to a new viewpoint and could only use an allocentric spatial representation. This approach provides a strict test for allocentric coding (without either a matching viewpoint or self-motion information) while avoiding additional task demands in previous studies (it does not require them to deal with a small table-top environment or to manage stronger cue conflicts). Both the younger and older groups were able to point back at the target location better than chance when they could use view matching and/or self-motion, but allocentric recall was only seen in the older group (4.0-4.5). In addition, we only obtained evidence for a specific kind of allocentric recall in the older group: they tracked one major axis of the space significantly above chance, r(158) = .28, but not the other, r(158) = -.01. We conclude that there is a major qualitative change in coding for spatial recall around the fourth birthday, potentially followed by further development towards fully flexible recall from new viewpoints.

Effects of two-dimensional versus three-dimensional landmark geometry and layout on young children's recall of locations from new viewpoints.

Spatial memory is an important aspect of adaptive behavior and experience, providing both content and context to the perceptions and memories that we form in everyday life. Young children's abilities in this realm shift from mainly egocentric (self-based) to include allocentric (world-based) codings at around 4 years of age. However, information about the cognitive mechanisms underlying acquisition of these new abilities is still lacking. We examined allocentric spatial recall in 4.5- to 8.5-year-olds, looking for continuity with navigation as previously studied in 2- to 4-year-olds and other species. We specifically predicted an advantage for three-dimensional landmarks over two-dimensional ones and for recalling targets "in the middle" versus elsewhere. However, we did not find compelling evidence for either of these effects, and indeed some analyses even support the opposite of each of these conclusions. There were also no significant interactions with age. These findings highlight the incompleteness of our overall theories of the development of spatial cognition in general and allocentric spatial recall in particular. They also suggest that allocentric spatial recall involves processes that have separate behavioral characteristics from other cognitive systems involved in navigation earlier in life and in other species.

Developmental differences in memory reactivation relate to encoding and inference in the human brain.

Despite the fact that children can draw on their memories to make novel inferences, it is unknown whether they do so through the same neural mechanisms as adults. We measured memory reinstatement as participants aged 7-30 years learned new, related information. While adults brought memories to mind throughout learning, adolescents did so only transiently, and children not at all. Analysis of trial-wise variability in reactivation showed that discrepant neural mechanisms-and in particular, what we interpret as suppression of interfering memories during learning in early adolescence-are nevertheless beneficial for later inference at each developmental stage. These results suggest that while adults build integrated memories well-suited to informing inference directly, children and adolescents instead must rely on separate memories to be individually referenced at the time of inference decisions.

Interpersonal Family Dynamics Relate to Hippocampal CA Subfield Structure.

Social environments that are extremely enriched or adverse can influence hippocampal volume. Though most individuals experience social environments that fall somewhere in between these extremes, substantially less is known about the influence of normative variation in social environments on hippocampal structure. Here, we examined whether hippocampal volume tracks normative variation in interpersonal family dynamics in 7- to 12-year-olds and adults recruited from the general population. We focused on interpersonal family dynamics as a prominent feature of one's social world. Given evidence that CA1 and CA2 play a key role in tracking social information, we related individual hippocampal subfield volumes to interpersonal family dynamics. More positive perceptions of interpersonal family dynamics were associated with greater CA1 and CA2/3 volume regardless of age and controlling for socioeconomic status. These data suggest that CA subfields are sensitive to normative variation in social environments and identify interpersonal family dynamics as an impactful environmental feature.

Contextual support for children's recall within working memory.

Measures of working memory capacity (WMC) are extremely popular, yet we know relatively little about the specific processes that support recall. We focused on children's and adults' ability to use contextual support to access working memory representations that might otherwise not be reported. Children ( N = 186, 5-10 years) and adults ( N = 64) completed a listening span task and a delayed recall task with semantic probes or cues. Clear age-related increases in listening span were evident. All age groups benefitted from contextual support to retrieve degraded target memoranda, particularly on listening span tasks when the cues provided semantic support for processing events, in comparison to cues associated specifically with memoranda. Response latencies suggested a developing efficiency in children's use of contextual support for delayed recall correlated with listening span performance. These probe tasks support accounts of working memory that recognise reconstructive and cued search processes.

Sensory cue combination in children under 10 years of age.

Cue combination occurs when two independent noisy perceptual estimates are merged together as a weighted average, creating a unified estimate that is more precise than either single estimate alone. Surprisingly, this effect has not been demonstrated compellingly in children under the age of 10 years, in contrast with the array of other multisensory skills that children show even in infancy. Instead, across a wide variety of studies, precision with both cues is no better than the best single cue - and sometimes worse. Here we provide the first consistent evidence of cue combination in children from 7 to 10 years old. Across three experiments, participants showed evidence of a bimodal precision advantage (Experiments 1a and 1b) and the majority were best-fit by a combining model (Experiment 2). The task was to localize a target horizontally with a binaural audio cue and a noisy visual cue in immersive virtual reality. Feedback was given as well, which could both (a) help participants judge how reliable each cue is and (b) help correct between-cue biases that might prevent cue combination. Crucially, our results show cue combination when feedback is only given on single cues - therefore, combination itself was not a strategy learned via feedback. We suggest that children at 7-10 years old are capable of cue combination in principle, but must have sufficient representations of reliabilities and biases in their own perceptual estimates as relevant to the task, which can be facilitated through task-specific feedback.

Direct and indirect influences of executive functions on mathematics achievement.

Achievement in mathematics is predicted by an individual's domain-specific factual knowledge, procedural skill and conceptual understanding as well as domain-general executive function skills. In this study we investigated the extent to which executive function skills contribute to these three components of mathematical knowledge, whether this mediates the relationship between executive functions and overall mathematics achievement, and if these relationships change with age. Two hundred and ninety-three participants aged between 8 and 25years completed a large battery of mathematics and executive function tests. Domain-specific skills partially mediated the relationship between executive functions and mathematics achievement: Inhibitory control within the numerical domain was associated with factual knowledge and procedural skill, which in turn was associated with mathematical achievement. Working memory contributed to mathematics achievement indirectly through factual knowledge, procedural skill and, to a lesser extent, conceptual understanding. There remained a substantial direct pathway between working memory and mathematics achievement however, which may reflect the role of working memory in identifying and constructing problem representations. These relationships were remarkably stable from 8years through to young adulthood. Our findings help to refine existing multi-component frameworks of mathematics and understand the mechanisms by which executive functions support mathematics achievement.

How do selective attentional processes contribute to maintenance and recall in children's working memory capacity?

The development of working memory capacity is considered from the perspective of the active maintenance of items in primary memory (PM) and a cue-dependent search component, secondary memory (SM). Using free recall, plus a more novel serial interleaved items task, age-related increases in PM estimates were evident in both paradigms. In addition to this, age-related improvements in attentional selectivity were observed, indexed by the recall of target and non-target information respectively. To further characterize PM, presentation modality was varied in the serial interleaved items task (auditory, visual and dual presentation). Developmental differences were found in the effectiveness of presentation formats. Older children's recall was enhanced by the combination of labeled visual items and enduring auditory information, whilst the same format was detrimental to younger children's recall of target information. The present results show how estimates of PM and SM in children relate to the development of working memory capacity, but measurement of these constructs in children is not straightforward. Data also points to age-related changes in selective attention, which in turn contributes to children's ability to process and maintain information in working memory.