Reexposure breeds recall: effects of experience on 9-month-olds' ordered recall

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.

Young Children's Representation of Locations in a Series: A Front-Back Representation or an Ordinal Representation?

Previous research has found that 3–5-year-old children could encode and retrieve a target location in a two-location series. In a paradigm of running two symmetrical railcars on a circular track, the study suggested that children used front-back array to help coding. That is, children at this age code the railcar running in the front of another as “the location in the front” and the railcar running in the back of another as “the location in the back.” However, the children’s success could be attributed to an alternative interpretation; using an ordinal representation to encode the location in front as the first with the other as the second. The current study used a four-location series to examine the children’s mental representation. Three- to five-year-old children participated in a hide-and-seek game to remember a target location out of four locations that moved in a series. The results showed salient individual differences in children’s representation, and their performance improved as the representation progressed. An ordinal representation supported the precise encoding of each location, while a vague front-back representation and a clearer front-middle-back representation led to different performance.

Participation in Social Skills Therapy is Associated With Enhanced Recall Memory by Children With Down Syndrome: An Exploratory Study

Participation in social skills therapy (SST) facilitates cognitive functioning in children with developmental disabilities. The present pilot study examined whether participation in SST was associated with enhanced encoding and 1-month delayed recall in children with Down syndrome (DS). Children were presented with novel three-step event sequences in an elicited imitation procedure. Immediate imitation was permitted as an index of encoding; long-term memory was assessed 1 month later. Parents completed questionnaires inquiring about children's participation in SST. Participation in SST was associated with enhanced encoding of temporal order information and 1-month delayed recall of individual target actions. In addition, encoding mediated the relation between group and 1-month delayed recall. The conducted research indicates that involvement in SST may be beneficial for children with DS despite their noted strengths in imitation and social learning. As such, additional experimental work is warranted to determine causality.

Cognitive Functioning in Children with Down Syndrome: Current Knowledge and Future Directions

Infants and children with Down syndrome (DS) can look forward toward bright futures, as individuals with DS are living healthier, more productive lives than ever due to medical advances, opportunities for early and continued intervention, and inclusive education. Despite these advances, infants and children with DS experience challenges in specific domains of cognitive functioning relative to their typically developing (TD) peers. Over the long term, individuals with DS are also more likely to develop Alzheimer's disease relative to the general population. Understanding cognitive functioning early in life may be important in charting cognitive decline over time. This chapter synthesizes the literature on cognitive functioning in infants and children with DS specific to general intelligence or IQ, language development, recall memory, and executive functioning, with additional focus on critical issues and future directions. These research findings provide important information for understanding cognitive competencies and intervention opportunities for children with DS and also serves to provide a foundation from which to plan longitudinal studies examining stability and change in cognitive functioning over time.

What three-year-olds remember from their past

From birth on, infants show long-term recognition memory for persons. Furthermore, infants from six months onwards are able to store and retrieve demonstrated actions over long-term intervals in deferred imitation tasks. Thus, information about the model demonstrating the object-related actions is stored and recognition memory for the objects as well as memory for the actions is retrieved. To study the development of long-term retention for different memory contents systematically, the present study investigated the recognition of person- and object-related information as well as the retention of actions in two samples of three-year-olds who had participated in a deferred imitation task at either nine or 18 months of age. Results showed that three-year-olds who had participated at nine months of age retained actions in a re-enactment task; however, they neither indicated person- nor object-recognition in a picture-choice task (recognition task). Children who had participated at 18 months of age demonstrated person- and object-recognition but no re-enactment at three years of age. Findings are discussed against the background of memory development from a preverbal to a verbal age and in regard to the characteristics of the recognition vs re-enactment tasks and the stimuli used.

Reality check: Prior exposure facilitates picture book imitation by 15-month-old infants

We examined whether 15-month-olds could imitate a novel action sequence from a picture book, and whether or not pre-exposure to the objects before reading the book would facilitate imitation. We found that infants only imitated from a picture book above baseline when they had previously interacted with the objects.

Developments in Long-Term Explicit Memory Late in the First Year of Life

Coincident with developments in the temporal-cortical explicit memory network, long-term recall abilities are newly emergent late in the first year of human life. We recorded event-related potentials (ERPs) in 9-month-olds as an index of the integrity of the neural substrate underlying a task thought to reflect explicit memory, namely, deferred imitation. ERP measures of recognition memory 1 week after unique laboratory experiences predicted whether and how much infants recalled of the experiences 1 month later. The findings further imply that memory storage and consolidation processes are a major source of variability in long-term recall memory late in the first year of life.

Long–Term Recall Memory: Behavioral and Neuro–Developmental Changes in the First 2 Years of Life

Until not long ago, psychologists conceptually and methodologically linked the capacity for recall of the past to developments in language. With the advent of a nonverbal measure of recall, this association has been challenged. It now is apparent that the capacity for long–term recall emerges well before the verbal ability to describe past experiences. Long–term recall is newly (or recently) emergent late in the 1st year of life; over the 2nd year, it consolidates and becomes reliable. The course of age–related changes in mnemonic behavior is consistent with current understanding of developments in the neural substrate implicated in recall memory.

Examining Recall Memory in Infancy and Early Childhood Using the Elicited Imitation Paradigm

The ability to recall the past allows us to report on details of previous experiences, from the everyday to the significant. Because recall memory is commonly assessed using verbal report paradigms in adults, studying the development of this ability in preverbal infants and children proved challenging. Over the past 30 years, researchers have developed a non-verbal means of assessing recall memory known as the elicited or deferred imitation paradigm. In one variant of the procedure, participants are presented with novel three-dimensional stimuli for a brief baseline period before a researcher demonstrates a series of actions that culminate in an end- or goal-state. The participant is allowed to imitate the demonstrated actions immediately, after a delay, or both. Recall performance is then compared to baseline or to performance on novel control sequences presented at the same session; memory can be assessed for the individual target actions and the order in which they were completed. This procedure is an accepted analogue to the verbal report techniques used with adults, and it has served to establish a solid foundation of the nature of recall memory in infancy and early childhood. In addition, the elicited or deferred imitation procedure has been modified and adapted to answer questions relevant to other aspects of cognitive functioning. The broad utility and application of imitation paradigms is discussed, along with limitations of the approach and directions for future research.

Recall memory in children with Down syndrome and typically developing peers matched on developmental age

BACKGROUND

Whereas research has indicated that children with Down syndrome (DS) imitate demonstrated actions over short delays, it is presently unknown whether children with DS recall information over lengthy delays at levels comparable with typically developing (TD) children matched on developmental age.

METHOD

In the present research, 10 children with DS and 10 TD children participated in a two-session study to examine basic processes associated with hippocampus-dependent recall memory. At the first session, the researcher demonstrated how to complete a three-step action sequence with novel stimuli; immediate imitation was permitted as an index of encoding. At the second session, recall memory was assessed for previously modelled sequences; children were also presented with two novel three-step control sequences.

RESULTS

The results indicated that group differences were not apparent in the encoding of the events or the forgetting of information over time. Group differences were also not observed when considering the recall of individual target actions at the 1-month delay, although TD children produced more target actions overall at the second session relative to children with DS. Group differences were found when considering memory for temporal order information, such that TD children evidenced recall relative to novel control sequences, whereas children with DS did not.

CONCLUSIONS

These findings suggest that children with DS may have difficulty with mnemonic processes associated with consolidation/storage and/or retrieval processes relative to TD children.

Vagal tone as a biomarker of long-term memory for a stressful social event at 4 months

This study investigates infants' memory for social stress after a 15-day retention interval using behavior and respiratory sinus arrhythmia (RSA). Experimental group infants were exposed to face-to-face still-face paradigm (FFSF) two times; the first time at 4 months and after a 2-week interval. Control group infants were exposed to FFSF only once at 4 months plus 2 weeks. Infants were categorized as suppressors or non-suppressors based on the direction of RSA change at first FFSF exposure. No behavioral differences were found among groups and exposure conditions. In the experimental group suppressors changed and showed no suppression when re-exposed 2 weeks later to FFSF. Non-suppressors showed no change in RSA from the first to the second exposure to FFSF. Control infants showed similar RSA changes to experimental infants at their first exposure. Findings indicate that 4-month-old infants have memory for social stress related to individual differences in autonomic reactivity.

Language facilitates event memory in early childhood: Child comprehension, adult-provided linguistic support and delayed recall at 16 months

Adult-provided supportive language facilitates memory for the past in preverbal and verbal children. Work conducted with 18-month-olds indicates that children benefit from supportive adult language when tested after a 4-week delay but not when tested immediately after sequence demonstration; moreover, findings reveal that supportive language provided only at test may be more facilitative of recall after a delay relative to supportive language provided only at encoding. In the present study, we examined whether child language comprehension abilities moderated the extent to which preverbal children benefitted from supportive language provided at encoding and test. The findings indicated that child language comprehension and supportive language provided at encoding were unassociated with performance at baseline or immediate imitation; however, the moderating effect of child language comprehension on adult-provided supportive language at encoding and test was observed after a 1-week delay. Correlations revealed continuous associations between general comprehension scores and recall performance after the 1-week delay on sequences presented in the most supportive condition at encoding. Taken together, the presented findings reveal that the complex interplay between language and cognition is established in early childhood, with foundational relations emerging before children are capable of verbally reporting on the past.

Four-month-old infants' long-term memory for a stressful social event

Infants clearly show an early capacity for memory for inanimate emotionally neutral events. However, their memory for social stress events has received far less attention. The aim of the study was to investigate infants' memory for a stressful social event (i.e., maternal unresponsiveness during the Still-Face paradigm) after a 15-day recall interval using changes in behavioral responses and salivary post-stress cortisol reactivity as measures of memory. Thirty-seven infants were exposed to social stress two times (experimental condition); the first time when they were 4 months of age and second exposure after a 2 week interval. Infants in the control condition (N = 37) were exposed to social stress just one time, at the age corresponding to the second exposure for infants in the experimental condition (4 months plus 2 weeks). Given individual differences in infants' reactivity to social stress events, we categorized infants as increasers or decreasers based on their cortisol reactivity after their initial exposure to the stress of the maternal still-face. Infants in the experimental condition, both increasers and decreasers, showed a significant change in cortisol response after the second exposure to the maternal still-face, though change was different for each reactivity group. In contrast, age-matched infants with no prior exposure to the maternal still-face showed similar post-stress cortisol reactivity to the reactivity of the experimental infants at their first exposure. There were no behavioral differences between increasers and decreasers during the Still-Face paradigm and exposures to the social stress. Thus differences between the experimental and control groups' post-stress cortisol reactivity was associated with the experimental group having previous experience with the social stress. These findings indicate long-term memory for social stress in infants as young as 4 months of age.

Effects of viewing ordered pictorial reminders on long-term memory in the first year of life

Previous research has shown that reminders can be effective for extending and enhancing a variety of kinds of memory in infants. We investigated the effects of viewing pictorial representations of actions that were included in imitation events used to measure long-term memory in young infants. Infants who saw the pictures of actions displayed in the order in which they comprised events showed evidence of memory for the events. Infants who saw the actions presented randomly did not. These results suggest that pictures presented during the consolidation and storage phase of memory formation can be effective reminders of events for young infants.

Memory for events and locations obtained in the context of elicited imitation: evidence for differential retention in the second year of life

Previous research has suggested that infants may have more robust memory for past experiences relative to memory for locations that have been encountered previously. This assertion, however, primarily results from the comparison of data that were collected using different experimental procedures. In the present study, we examined memory for events and memory for locations in the context of elicited imitation. Specifically, 13-, 16-, and 20-month-old infants were tested for long-term memory for events and locations after between-subjects delays of 1, 3, 6, 9, and 12 months. The results indicated that the event memory was retained over lengthier delays relative to the location memory, despite superior encoding of location information. The possible adaptive significance of long-term memory for events ontogenetically preceding long-term memory for locations is discussed.

Consequences of low neonatal iron status due to maternal diabetes mellitus on explicit memory performance in childhood

Diabetic pregnancies are characterized by chronic metabolic insults, including iron deficiency, that place the developing brain at risk for memory impairment later in life. A behavioral recall paradigm coupled with electrophysiological measures was used to assess the longevity of these effects in 40 3(1/2)-year-old children. When memory demands were high, recall was significantly impaired in the at-risk group and correlated with perinatal measures of iron. Electrophysiological results suggested both encoding and retrieval processes were compromised. These findings support the hypothesis that prenatal iron deficiency leads to alterations in neural development that have a lasting impact on memory ability.

The development of imitation in infancy

An overview of existing data on imitation in infancy suggests that changes in the direction of imitation research are underway. The widely accepted view that newborn infants imitate lacks supporting evidence. Instead, existing data suggest that infants do not imitate others until their second year, and that imitation of different kinds of behaviour emerges at different ages. The evidence is consistent with a dynamic systems account in which the ability to imitate is not an inherited, specialized module, but is instead the emergent product of a system of social, cognitive and motor components, each with its own developmental history.

Going beyond the specifics: generalization of single actions, but not temporal order, at 9 months

We examined generalization in 9-month-old infants after a 24-h delay using deferred imitation. Infants flexibly applied their knowledge of sequence actions across changes in props even though they had no opportunity for immediate imitation.

Der Frankfurter Imitations-Test für 12 Monate alte Kinder (FIT 12)

Zusammenfassung. Die Erforschung des Gedächtnisses von präverbalen Kindern nimmt in der modernen Entwicklungspsychologie einen breiten Raum ein. Es besteht dabei Konsens dahingehend, dass die Methode der Verzögerten Imitation (VI) das Verfahren ist, das deklaratives Gedächtnis im Verlauf der Ontogenese am frühesten erfassen kann. Im deutschen Sprachraum gibt es bislang kein erprobtes Instrumentarium, das für die Messung deklarativer Gedächtnisleistungen mittels VI erprobt worden wäre. Im Anschluss an die Darstellung der Grundlagen des Messverfahrens wird über eine Studie mit n = 92 Einjährigen berichtet, in der eine Aufgabenserie zur VI erprobt (Frankfurter Imitations-Test für 12 Monate alte Kinder, FIT 12) wurde. Dieses neu entwickelte Instrument erwies sich als altersadäquat. Die zwischen den Einjährigen gemessenen Leistungsunterschiede erwiesen sich zudem in einer Test-Retest-Reliabilitätsstudie nach einem Zeitintervall von einer Woche als stabil (Goertz et al., under revision). Schließlich konnten Belege für die Konstruktvalidität dieses Gedächtnistests erbracht werden.

Electrophysiological Indexes of Encoding and Behavioral Indexes of Recall: Examining Relations and Developmental Change Late in the First Year of Life

Long-term memory undergoes pronounced development in the latter part of the 1st year. This research combines electrophysiological (event-related potential [ERP]) and behavioral (deferred imitation) measures of encoding and recall, respectively, in an examination of age-related changes in and relations between encoding and recall during this time. In a short-term longitudinal study, infants were exposed to different multistep sequences at 9 and at 10 months. In both phases, they were tested for immediate recognition of the events via ERPs (as an index of encoding), and for recall of them 1 month later. At both ages, infants encoded the events; encoding was more robust at 10 months than at 9 months. After the 1-month delay, infants failed to recall the events experienced at 9 months, but evidenced recall of the events experienced at 10 months. In spite of developmental differences in encoding and recall over this period, indexes of encoding at 9 months were correlated with measures of recall of events experienced at 10 months and tested 1 month later.

Forming a stable memory representation in the first year of life: why imitation is more than child's play

Although 9-month-old infants are capable of retaining temporally ordered information over long delays, this ability is relatively fragile. It may be possible to facilitate long-term retention by allowing infants to imitate event sequences immediately after their presentation. The effects of imitation on immediate and delayed recognition and on long-term recall were investigated using event-related potentials (ERPs) and elicited imitation, respectively. Mnemonic facilitation resulting from the opportunity to imitate was apparent using both assessments. ERP assessments at immediate and delayed recognition tests suggested that infants who were allowed to imitate had stronger memory representations of familiar stimuli relative to infants who only viewed the presentation of the events. In addition, infants who were allowed to imitate evidenced higher levels of ordered recall after 1 month relative to infants who only watched the experimenter's demonstration. Therefore, imitation proved to have beneficial effects on explicit memory in 9(1/2)-month-olds, providing evidence of its effectiveness as a tool to augment mnemonic capabilities in infancy.

Perception of serial order in infants

Serial order is fundamental to perception, cognition and behavioral action. Three experiments investigated infants' perception, learning and discrimination of serial order. Four- and 8-month-old infants were habituated to three sequentially moving objects making visible and audible impacts and then were tested on separate test trials for their ability to detect auditory, visual or auditory-visual changes in their ordering. The 4-month-old infants did not respond to any order changes and instead appeared to attend to the 'local' audio-visual synchrony part of the event. When this local part of the event was blocked from view, the 4-month-olds did perceive the serial order feature of the event but only when it was specified multimodally. In contrast, the 8-month-old infants perceived all three kinds of order changes regardless of whether the synchrony part of the event was visible or not. The findings show that perception of spatiotemporal serial order emerges early in infancy and that its perception is initially facilitated by multimodal specification.