Real-time teaching and learning: Caregivers teaching infants to descend stairs.

Learning to descend stairs requires motor and cognitive capacities on the part of infants and opportunities for practice and assurance of safety offered by caregivers. The American Academy of Pediatrics prescribes the age strategy to teach toddlers to safely descend stairs but without much consideration for individual differences in infants' skills or caregivers' techniques. The purpose of this study was to observe the natural ways in which caregivers teach infants to descend stairs at home and the extent to which infants abide. Of particular interest was to examine the dynamic nature of caregivers' teaching and infants' learning over the session with attention to individual differences. Dyads (N = 59) were videorecorded on Zoom for 10 min interacting on stairs at home in the United States, Brazil, Canada, Italy, and Spain. Infants (n = 30 girls, 29 boys; 13-month-olds ± 1 week) were novice walkers (M = 2.04 months walking experience). Caregivers used a variety of teaching strategies and focused on "backing" and "scooting." Infants were more likely to heed caregivers' guidance when caregivers provided hands-on support and verbal encouragement suggesting infants were engaged and responsive to caregivers' overtures. Infants' walking experience predicted change in descent strategy over the session. Although infants did not show evidence of learning over the session, consistent caregiver instruction suggested caregivers were persistent, if not effective, teachers. Teaching and learning motor skills in a potentially risky task creates a unique opportunity for interaction, allowing infants and caregivers to learn from one another. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Three decades of infant motor development: Cohort effects in motor skill onsets.

Infant motor development is affected by the sociocultural context in which it takes place. Because societal and cultural practices are dynamic, this exploratory study examined whether the ages at which infants typically learned to crawl, cruise, and walk changed over the past 3 decades. We compiled archival data from 1,306 infants born between January 31, 1992, and December 10, 2021. Parents originally reported milestone onsets in interviews and by using diaries. For each motor milestone, a linear regression model predicted the onset age using birth date. Segmented regression analyses inspected changes in slopes over time. Covariates included rural/urban housing, gestation age, season of birth, and birth weight. Infants' average crawling, cruising, and walking onset ages changed over time. After controlling for the covariates, infants' crawling onset age steadily increased until 2012, after which crawling onset age decreased. Infants' cruising onset age increased from 1991 to 2001, after which cruising onset age remained stable. After controlling for the covariates, infants' walking onset increased until 2015, after which walking onset age decreased. Thus, when infants were born explained a small but significant amount of variability in infant motor skill onset. While the current study showed that motor development changed over the years, motor development is just a model system for development more generally: Cohort effects may be pervasive across developmental domains. Using motor development as a model system for studying change suggests that generational effects due to a changing society may be pervasive across developmental domains. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Infant motor development predicts the dynamics of movement during sleep.

The characteristics of infant sleep change over the first year. Generally, infants wake and move less at night as they grow older. However, acquisition of new motor skills leads to temporary increases in night waking and movement at night. Indeed, sleep-dependent movement at night is important for sensorimotor development. Nevertheless, little is known about how movement during sleep changes as infants accrue locomotor experience. The current study investigated whether infant sleep and movement during sleep were predicted by infants' walking experience. Seventy-eight infants wore an actigraph to measure physical activity during sleep. Parents reported when their infants first walked across a room >10 feet without stopping or falling. Infants in the midst of walking skill acquisition had worse sleep than an age-group estimate. Infants with more walk experience had more temporally sporadic movement during sleep and a steeper hourly increase in physical activity over the course of the night. Ongoing motor skill consolidation changes the characteristics of movement during sleep and may alter sleep state-dependent memory consolidation. We propose a model whereby changes in gross motor activity during night sleep reflect movement-dependent consolidation.

The unique contributions of day and night sleep to infant motor problem solving.

The current study sought to tease apart the unique contributions of napping and nighttime sleep to infant learning, specifically in the context of motor problem solving. We challenged 54 walking infants to solve a novel locomotor problem at three time points-training, test, and follow-up the next morning. One group of infants napped during the delay between training and test. Another group did not sleep during the delay. A third group received the test immediately after training with no delay. Only the Nap group's strategy choices continued to improve through the follow-up session, suggesting that daytime sleep has an active role in strengthening otherwise fragile memory. Although group did not affect strategy maintenance, walk experience did, suggesting that task difficulty may shape the impact of sleep on learning. Thus, day sleep and night sleep make independent contributions to the consolidation of motor problem-solving strategies during infancy.

Nap timing makes a difference: Sleeping sooner rather than later after learning improves infants' locomotor problem solving.

Twenty-nine newly-walking infants who had recently given up crawling trained to navigate a shoulder-height, nylon tunnel to reach a caregiver waiting at the other end. Infants in the Nap First group napped within 30 min of initial training. Infants in the Delay First group napped four hours after training. All infants were retested six hours after training on the same locomotor problem. Learning was measured by the number of training prompts required to solve the task, exploration, and time to solve the problem. Nap First infants benefited the most from a nap; they required fewer training prompts, used fewer posture shifts from training to test, and solved the task faster compared to Delay First infants, suggesting that optimally timed sleep does not merely protect against interference, but actively contributes to memory consolidation. This study highlights the importance of nap timing as a design feature and was a first step towards limit-testing the boundaries of the relation between sleep and learning. Infants' fragile memories require regular consolidation with intermittent periods of sleep to prevent interference or forgetting.

Researcher Choices for Infant Sleep Assessment: Parent Report, Actigraphy, and a Novel Video System.

Incorporating infant sleep, either as a predictor or as an outcome variable, into interdisciplinary work has become increasingly popular. Sleep researchers face many methodological choices that have implications for the reliability and validity of the data. Here, the authors directly investigated the impact of design and measurement choices in a small, longitudinal sample of infants. Three sleep measurement techniques-parent-reported sleep diaries, actigraphy (Micromini Sleep Watch), and a commercial videosomnography (Nanit)-were included, using actigraphy as the baseline. Nine infants' sleep (4 girls) was measured longitudinally using all three measurement techniques. Nanit provided summary statistics, using a proprietary algorithm, for nightly sleep parameters. The actigraphy data were analyzed with both the Sadeh Infant and Sadeh algorithms. The extent to which measurements converged on sleep start and end time, number of wake episodes, sleep efficiency, and sleep duration was assessed. Measures were positively correlated. Difference scores revealed similar patterns of greater sleep estimation in parent reports and Nanit compared with actigraphy. Bland-Altman plots revealed that much of the data were within the limits of agreement, tentatively suggesting that Nanit and actigraphy may be used interchangeably. Graphs display significant variability within and between individual infants as well as across measurement techniques. Potential confounding variables that may explain the discrepancies between parent report, Sadeh Infant, Sadeh, and Nanit are discussed. The findings are also used to speak to the advantages and disadvantages of design and measurement choices. Future directions focus on the unique contributions of each measurement technique and how to capitalize on them.

Making the process of strategy choice visible: Inhibition and motor demands impact preschoolers' real-time problem solving.

To examine the real-time process of strategy choice and execution and the role of inhibition in problem solving, 4- to 6-year-old children were asked to navigate a ball around a maze board under high- and low-precision motor demands. Employing a motor problem-solving task made normally hidden cognitive processes observable. Sequential analysis revealed two subtypes of inhibition (response and attentional) that are involved in problem solving and different developmental trajectories for each. Cognition-action trade-offs due to motor and inhibition demands adversely impacted children's strategy choices, but contributed to heightened variability of strategies. Children used fewer strategies with age, reflecting more efficient problem solving due to increasing inhibitory control. When solutions required precision, preschoolers were more likely to have difficulty inhibiting irrelevant and distracting strategies and maintaining appropriate strategies. By preschool age, executive functioning serves to make strategic motor control possible. A video abstract of this article can be viewed at https://www.youtube.com/watch?v=TCLxK7dvheE.

Newly walking infants' night sleep impacts next day learning and problem solving.

Sleep is part of the process that prepares children and adults for next day cognitive activity. Insufficient or fragmented sleep has a detrimental impact on subsequent encoding (Rouleau et al., 2002) and cognitive functioning (Joo et al., 2012). However, fragmented sleep early in life is a developmental norm, limiting the extent to which conclusions derived from older populations can be generalized. To directly test the continuity of this relationship, newly-walking infants' (N=58) sleep was monitored overnight using actigraphy. The next morning they were taught a motor problem-solving task. The task required infants to navigate through a tunnel to reach a goal at the other end. We coded infants' exploratory behaviors and the extent of training required to solve the task. Using a cluster analysis that accounted for exploratory behaviors and number of training prompts, infants were sorted into three profiles: those who found the task Easy to solve, those who found it Difficult, and those who Never solved it. Wake episodes and sleep efficiency were entered as predictors of cluster membership in a multinomial logistic regression. Of the infants who ultimately solved the task, those with more wake episodes and lower sleep efficiency had more difficulty. Specifically, fragmentation appeared to negatively impact preparedness to learn. Contrary to our expectations, infants who Never solved the task had the least fragmented sleep, indicating that an optimal level of fragmentation is needed for efficient problem-solving. For infants, some level of sleep fragmentation is needed the night before learning in order to solve a task efficiently. These findings highlight the interaction between developmental domains, from sleep quality to motor experience, and their impact on infant learning in real time.