Self-regulation and frontal EEG alpha activity during infancy and early childhood: A multilevel meta-analysis.

Integrating behavioral and neurophysiological measures has created new and advanced ways to understand the development of self-regulation. Electroencephalography (EEG) has been used to examine how self-regulatory processes are related to frontal alpha power during infancy and early childhood. However, findings across previous studies have been inconsistent. To address this issue, the current meta-analysis synthesized all prior literature examining associations between individual differences in self-regulation and frontal EEG alpha power (baseline and/or task). In total, 23 studies consisting of 1275 participants between 1 month and 6 years of age were included, which yielded 149 effect sizes. Findings of the three-level meta-analytic model demonstrated a non-significant overall association between self-regulation and frontal alpha power. Yet, significant moderating effects were found for self-regulation construct (emotion regulation, effortful control, executive function), self-regulation measurement (behavioral task, computer assessment, lab observation, questionnaire), and children's mean age. Self-regulation was only significantly correlated with frontal alpha power when studies focused on the executive functioning construct. Moreover, the use of behavioral tasks or questionnaires and a higher mean age of the children resulted in small but significant effect size estimates. Higher frontal alpha power values were related to higher order top-down mechanisms of self-regulation, indicating that these mechanisms might become stronger when the frontal cortex is sufficiently developed. The findings of the current meta-analysis highlight the importance of longitudinal analyses and multimethod approaches in future work to reach a more comprehensive understanding of the role of frontal EEG alpha activity in the etiology of individual differences in early self-regulation. RESEARCH HIGHLIGHTS: The first meta-analysis of individual differences in self-regulation and frontal EEG alpha power during infancy and early childhood demonstrated a non-significant overall association. Moderation analyses revealed that variations in frontal alpha power were significantly associated with executive function, but not with effortful control and emotion regulation. Frontal alpha power was related to variations in self-regulation when measured by behavioral tasks and questionnaires, but not via computer assessments and lab observations. The association between individual differences in self-regulation and frontal alpha power becomes significantly stronger with age.

The effects of reward on children's Stroop performance: Interactions with temperament.

The effects of rewards on executive function (EF) reflect bidirectional interactions among motivational and executive systems that vary with age and temperament. However, methodological limitations hinder understanding of the precise influences of incentives on early EF, including the role of reward sensitivity. In this within-subjects study, ninety-three 3.5- to 5-year-olds (42 girls; 22% Hispanic; 78% White) residing in the United States completed equivalent EF measures (Stroop and non-Stroop phases) in both rewarded and non-rewarded conditions. Rewards enhanced Stroop accuracy and slowed overall response times (ds = 0.29-0.40). Critically, children with low parent-reported reward sensitivity exhibited greater reward-based increases in Stroop accuracy (r = -.30). These findings provide valuable insights on early motivation-cognition integration, highlighting temperament as a mechanism underlying these interactions.

Memory binding and theta EEG during middle childhood.

The ability to bind together the contextual details associated with an event undergoes dramatic improvement during childhood. However, few studies have examined the neural correlates of memory binding encoding and retrieval during middle childhood. We examined age-related encoding and retrieval differences using continuous electroencephalogram (EEG) measures in a sample of 6- and 8-year-olds. For the memory binding task, children were tested on memory for individual items (i.e., objects and backgrounds only) and combined object-backgrounds pairings (combination condition). Memory for individual item information was comparable across both age groups. However, younger children experienced greater difficulty (i.e., higher false alarm rate) in the combination condition. Theta (4-7 Hz) neuronal oscillations were analyzed to compare memory encoding and retrieval processes. Widespread retrieval-related increases in theta band EEG power (compared with baseline and encoding-related activation) were evident in both 6- and 8-year-olds. Regression analyses revealed that parietal theta EEG power during retrieval accounted for variability in memory binding performance. These findings suggest that theta rhythms are intricately linked to memory binding processes during middle childhood.

Effects of active and observational experience on EEG activity during early childhood.

While it is accepted that action experience facilitates action understanding, it is debated whether first-hand motor and visual experience differentially influence this ability. Action understanding relies on relatively broad cortical activity, including that of the neural mirroring and visual attention systems. Infant and adult research has demonstrated that prior motor and visual experience have distinct effects on cortical activity during action perception, though this has yet to be investigated in young children. We used a within-subject design and an at-home training paradigm to manipulate 3- to 6-year-olds' experience with two relatively novel actions. On Days 1-4, children received brief active training with one tool (i.e., motor experience) and observational training with the other tool (i.e., visual experience: video of a demonstrator modeling the action). On Day 5, we measured children's EEG mu/alpha (8-10 Hz) and beta rhythm (16-20 Hz) activity during observation and execution of these actions in the laboratory. Although central-parietal mu and beta rhythm activity did not differ as a function of training condition, desynchronization of the occipital alpha rhythm was greater during perception of the active training task than of the observational training task. Our findings suggest that, during early childhood, action experience may modulate visual attention during subsequent action perception. Further, children exhibited neural mirroring-central-parietal desynchronization during both tool-use action observation and execution-within the mu rhythm, but not the beta rhythm. These findings have significant implications for our understanding of the broad cortical activity that supports action perception during this period.

Ontogenesis of learning and memory: Biopsychosocial and dynamical systems perspectives.

In this article, we review recent empirical and theoretical work on infant memory development, highlighting future directions for the field. We consider the state of the field since Carolyn Rovee-Collier's call for developmental scientists to "shift the focus from what to why," emphasizing the function of infant behavior and the value of integrating fractionized, highly specialized subfields. We discuss functional approaches of early learning and memory, including ecological models of memory development and relevant empirical work in human and non-human organisms. Ontogenetic changes in learning and memory occur in developing biological systems, which are embedded in broader socio-cultural contexts with shifting ecological demands that are in part determined by the infants themselves. We incorporate biopsychosocial and dynamical systems perspectives as we analyze the state of the field's integration of multiple areas of specialization to provide more holistic understanding of the contributing factors and underlying mechanisms of the development of memory.

A Longitudinal Investigation of Conflict and Delay Inhibitory Control in Toddlers and Preschoolers.

RESEARCH FINDINGS: Eighty-one children participated in a longitudinal investigation of inhibitory control (IC) from 2 to 4 years of age. Child IC was measured via maternal report and laboratory measures under conditions of conflict and delay. Performance on delay IC tasks at 3 years was related to performance on these same tasks at 2 and 4 years, but performance on conflict IC tasks was not related over time. Delay IC task performance was concurrently related to conflict IC task performance in 3- and 4-year-olds but not related in 2-year-olds. Measures of IC varied in their associations with measures of verbal ability and maternal report IC. Such findings highlight important similarities and distinctions between conflict and delay IC abilities in their relation to one another and to temperament and language over time. PRACTICE OR POLICY: Studies of IC and related concepts reveal that children who are regulated enjoy school more and have higher school competence, particularly in mathematics and reading achievement. Because conflict IC and delay IC show unique patterns of development over time, educators can expect classroom behaviors drawing upon the state-like conflict IC to show more fluctuation over time than those drawing on the trait-like delay IC.

Transitions in the temporal parameters of sensory preconditioning during infancy.

Sensory preconditioning (SPC) is a form of latent learning in which preexposure to co-occurring neutral stimuli (S1 -S2 ) permits subsequent learning to be transferred from one stimulus (S1 ) to the other (S2 ). We examined whether human infants exhibit developmental transitions in the temporal parameters of SPC by manipulating the preexposure regimen. Infants received simultaneous or sequential preexposure to puppets S1 and S2 (Days 1-2); saw target actions modeled on S1 (Day 3); and were tested for deferred imitation with S2 (Day 4). Although 6-, 9-, and 12-month-olds associated the puppets, there was a shift in the effective regimen from simultaneous to sequential preexposure-similar to prior findings with rat pups (Experiment 1). Experiment 2 revealed that human infants potentially exhibit another transition in SPC at 15 and 18 months of age. We consider the roles of ontogenetic shifts in infants' ecological niche, selective attention, and unitization in developmental transitions in SPC.

A dissociation between recognition and reactivation: The renewal effect at 3 months of age.

Extinction allows organisms to adapt to an ever-changing environment. Despite its theoretical and applied significance, extinction has never been systematically studied with human infants. Using the operant mobile task, we examined whether 3-month-olds would exhibit evidence of original learning following extinction. In a recognition paradigm, infants exhibited renewal when tested in the acquisition context (ABA renewal) or a neutral context (ABC and AAB renewal) 1 day following extinction (Experiment 1a) and spontaneous recovery 3 days following extinction (Experiment 1b). In Experiments 2a-2b, we used a reminder paradigm to examine whether the extinguished response could be reinstated after the operant response had been forgotten. We failed, however, to find reinstatement of extinguished responding after spontaneous forgetting, regardless of the reminder and test contexts. We attributed this retention failure to competing responses at test. Although extinguished responding is recovered during infancy, this effect is elusive after the response has been forgotten.

To Stroop or not to Stroop: Sex-related differences in brain-behavior associations during early childhood.

Executive functions (EFs) are linked with optimal cognitive and social-emotional development. Despite behavioral evidence of sex differences in early childhood EF, little is known about potential sex differences in corresponding brain-behavior associations. The present study examined changes in 4-year-olds' 6-9 Hz EEG power in response to increased executive processing demands (i.e., "Stroop-like" vs. "non-Stroop" day-night tasks). Although there were no sex differences in task performance, an examination of multiple scalp electrode sites revealed that boys exhibited more widespread changes in EEG power as compared to girls. Further, multiple regression analyses controlling for maternal education and non-EF performance indicated that individual differences in boys' and girls' EF performance were associated with different frontal neural correlates (i.e., different frontal scalp sites and different measures of EEG power). These data reveal valuable information concerning sex differences in the neural systems underlying executive processing during early childhood.

Deconstructing the reactivation of imitation in young infants.

Reactivation is an automatic, perceptual process in which exposure to components of a forgotten event alleviates forgetting. Most research on infant memory reactivation has used conditioning paradigms. We used the puppet imitation task to systematically examine which stimuli could retrieve 6-month-olds' forgotten memory of the modeled actions. Infants watched an adult model a sequence of actions on a puppet, imitated the actions, and were exposed to reactivation cues 24 hr before a 7-day (Experiment 1) or 14-day (Experiment 2) retention test. Exposure to any component of the original event reactivated the memory during the 7-day test, but two of the same components failed to alleviate forgetting during the 14-day test. Increasing the number of retrieval cues facilitated 14-day test performance. These findings reveal that the principles of reactivation are the same for conditioning and imitation paradigms: The necessary and sufficient conditions for memory reactivation are directly related to memory accessibility.

Episodic memory and future thinking during early childhood: Linking the past and future.

Despite extensive examination of episodic memory and future thinking development, little is known about the concurrent emergence of these capacities during early childhood. In Experiment 1, 3-year-olds participated in an episodic memory hiding task ("what, when, where" [WWW] components) with an episodic future thinking component. In Experiment 2, a group of 4-year-olds (including children from Experiment 1) participated in the same task (different objects and locations), providing the first longitudinal investigation of episodic memory and future thinking. Although children exhibited age-related improvements in recall, recognition, and binding of the WWW episodic memory components, there were no age-related changes in episodic future thinking. At both ages, WWW episodic memory performance was higher than future thinking performance, and episodic future thinking and WWW memory components were unrelated. These findings suggest that the WWW components of episodic memory are potentially less fragile than the future components when assessed in a cognitively demanding task.

A longitudinal intergenerational analysis of executive functions during early childhood.

Despite the importance of executive function (EF) in both clinical and educational contexts, the aetiology of individual differences in early childhood EF remains poorly understood. This study provides the first longitudinal intergenerational analysis of mother-child EF associations during early childhood. A group of children and their mothers (n = 62) completed age-appropriate EF tasks. Mother and child EFs were modestly correlated by 24 months of age, and this association was stable through 48 months. Importantly, maternal-child EF associations were still robust after controlling for verbal ability (potential indicator of verbal/crystallized intelligence) and maternal education (correlate of socio-economic status and verbal intelligence). Potential implications of these findings as well as underlying mechanisms of the maternal-child EF association (gene-environment interplay) are discussed.

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 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 executive function. Six-year-olds recalled more fact and source information than 4-year-olds. Regression analyses revealed that age, language ability, and executive function accounted for unique variance in children's fact recall and source recall performance. These findings suggest a link between episodic memory and executive function, and we propose that developmental investigations should further explore this association.

The Infant EEG Mu Rhythm: Methodological Considerations and Best Practices.

The EEG mu rhythm, recorded from scalp regions overlying the sensorimotor cortex, appears to exhibit mirroring properties: It is reactive when performing an action and when observing another perform the same action. Recently, there has been an exponential increase in developmental mu rhythm research, partially due to the mu rhythm's potential role in our understanding of others' actions as well as a variety of other social and cognitive processes (e.g., imitation, theory of mind, language). Unfortunately, various methodological issues impede integrating these findings into a comprehensive theory of mu rhythm development. The present manuscript provides a review of the infant mu rhythm literature while focusing on current methodological problems that impede between study comparisons. By highlighting these issues and providing an in depth description and analysis we aim to heighten awareness and propose guidelines (when possible) that will promote rigorous infant mu rhythm research and facilitate between study comparisons. This paper is intended as a resource for developmental scientists, regardless of EEG expertise.

What's mom got to do with it? Contributions of maternal executive function and caregiving to the development of executive function across early childhood.

Executive functions (EFs; e.g. working memory, inhibitory control) are mediated by the prefrontal cortex and associated with optimal cognitive and socio-emotional development. This study provides the first concurrent analysis of the relative contributions of maternal EF and caregiving to child EF. A group of children and their mothers (n = 62) completed age-appropriate interaction (10, 24, 36 months) and EF tasks (child: 24, 36, and 48 months). Regression analyses revealed that by 36 months of age, maternal EF and negative caregiving behaviors accounted for unique variance in child EF, above and beyond maternal education and child verbal ability. These findings were confirmed when using an early child EF composite-our most reliable measure of EF - and a similar pattern was found when controlling for stability in child EF. Furthermore, there was evidence that maternal EF had significant indirect effects on changes in child EF through maternal caregiving. At 24 months, EF was associated with maternal EF, but not negative caregiving behaviors. Taken together, these findings suggest that links between negative caregiving and child EF are increasingly manifested during early childhood. Although maternal EF and negative caregiving are related, they provide unique information about the development of child EF. A video abstract of this article can be viewed at http://www.youtube.com/watch?v=NPKXFbbrkps.

Infant attention and early childhood executive function.

Individual differences in infant attention are theorized to reflect the speed of information processing and are related to later cognitive abilities (i.e., memory, language, and intelligence). This study provides the first systematic longitudinal analysis of infant attention and early childhood executive function (EF; e.g., working memory, inhibitory control, cognitive flexibility). A group of 5-month-olds (n = 201) were classified as short or long lookers. At 24, 36, and 48 months of age, children completed age-appropriate EF tasks. Infant short lookers (i.e., more efficient information processors) exhibited higher EF throughout early childhood as compared to infant long lookers, even after controlling for verbal ability (a potential indicator of intelligence). These findings are discussed in relation to the emergence of executive attention.

Using EEG to Study Cognitive Development: Issues and Practices.

Developmental research is enhanced by use of multiple methodologies for examining psychological processes. The electroencephalogram (EEG) is an efficient and relatively inexpensive method for the study of developmental changes in brain-behavior relations. In this review, we highlight some of the challenges for using EEG in cognitive development research. We also list best practices for incorporating this methodology into the study of early cognitive processes. Consideration of these issues is critical for making an informed decision regarding implementation of EEG methodology.

Early Childhood Predictors of Post-Kindergarten Executive Function: Behavior, Parent-Report, and Psychophysiology.

RESEARCH FINDINGS: This study examined whether children's executive functions before kindergarten would predict variance in executive functions after kindergarten. We obtained behavioral (working memory task performance), parental-reported (temperament-based inhibitory control), and psychophysiological (working memory-related changes in heart rate and brain electrical activity) measures of executive functions from a group of preschool-aged children. After children finished kindergarten, approximately 2 years later, parents were asked to complete an assessment of children's executive function skills. A regression analysis revealed that pre-kindergarten behavioral, parental-reported, and psychophysiological measures accounted for variance in post-kindergarten executive functions. Specifically, working memory task performance, temperament-based inhibitory control, and working memory-related changes in brain electrical activity accounted for unique variance in post-kindergarten executive functions. These data provide a unique contribution to the executive function literature: No other study has examined whether behavioral, psychophysiological, and parental-reported executive function measures can account for unique variance in future executive function. PRACTICE OR POLICY: These findings are discussed in relation to children's transition to school and executive function training programs.