Mother–child interaction and sleep regulation in one‐year‐olds

The regulation of sleep–wake states is controlled not only by biological mechanisms but by care‐giving context as well. In this study the association between mother–child relationship and the infant's sleep was examined. Thirty‐seven 12‐month‐olds and their mothers participated in a 10‐minute laboratory play episode. The dyadic interaction was coded with the Early Parent–Child Relational Assessment (Clark, 1985) and with the Emotional Availability scales (Biringen, Robinson, & Emde, 1993). The child's sleep was measured at home with a small‐computerized activity monitor. Although mothers' behavior was not related to the child's sleep, infants who were more responsive in the play episode woke up more frequently compared to infants who were less involved in the interaction. The link between social‐emotional competency and fragmented sleep, among nonrisk infants, could be an age‐related phenomenon. ©2001 Michigan Association for Infant Mental Health.     

爬行经验对婴儿迂回行为发展的影响

该研究旨在探讨个体早期第一种自主位移动作－爬行的经验对迂回行为这一重要空间认知能力发展的和用及其特点。     

Detection of the relevant type of locomotion in infancy: crawlers versus walkers

Human infants show a preference for individuals who are similar to them. Using point-light displays of human walkers and crawlers as stimuli, we examined whether infants' preference for the motions of crawling and walking changes between, before, and after the onset of bipedal walking. The results show that crawling and walking infants prefer the types of locomotion that are similar to their own, respectively. These indicate that the infants detect the similarities between the motions they performed and they observed, which provides the behavioral evidence that the production of a particular motion is connected to its perception in infancy.     

The role of crawling and walking experience in infant spatial memory

This research explored infants' use of place learning and cue learning in a locomotor task across the transition from crawling to walking. Novice and expert crawling and walking infants were observed in a novel locomotor task-finding a hidden goal location in a large space. In Experiment 1, infants were tested with distal landmarks. Infants with fewer than 6 weeks of experience, either crawling or walking, could not find the goal location. All infants with more locomotor experience were more successful. Learning did not transfer across the transition to walking. In Experiment 2, novice and expert crawlers and walkers were tested with a direct landmark. Again, novice crawlers and walkers with fewer than 6 weeks of experience could not find the goal, whereas those with more experience could. Taken together, these findings suggest that infants' spatial learning is inextricably linked to mode of locomotion.     

Early infant crawling experience is reflected in later motor skill development

The influences of early crawling experience on motor skill development were examined in children identified by parents as crawlers or noncrawlers during early infancy. Relative to the performance of crawlers, noncrawlers showed lower average and subtest-specific performance on selected measures of the Miller Assessment for Preschoolers. These results, interpreted through Ayres' sensory integration theory and applied to current occupational therapy practice, support Farber's hypothesized importance of early crawling experience in the development of sensory and motor systems of the body and general motor skill development.     

Longitudinal assessment of leg motor activity and sleep patterns in infants with and without Down syndrome

Whether infants with Down syndrome (DS) perform leg movements with the same frequency and quality as their typical development (TD) counterparts is equivocal. Furthermore, the relationship between these early leg movements and later onset of locomotor milestones has only been partially explored. The aims of this study were two-fold: (1) to describe the longitudinal leg activity in infants with and without DS (3-6 months), and (2) to examine sleeping patterns and leg activity during the night. In addition, the relationships between leg activities and sleep patterns with locomotor development were explored. An activity monitor was placed monthly on the infant's ankle for 48 h. Data were analyzed to separate day-night, high-low activity, and sleep fragmentation. The results indicate that infants with DS produced more low intensity activity and more fragmented sleep. These findings are discussed in relation to the influence of early motor activity on achievement of functional motor behavior.     

A new twist on old ideas: how sitting reorients crawlers

Traditionally, crawling and sitting are considered distinct motor behaviors with different postures and functions. Ten‐ to 12‐month‐old infants were observed in the laboratory or in their homes while being coaxed to crawl continuously over long, straight walkways (Study 1; N = 20) and during spontaneous crawling during free play (Study 2; N = 20). In every context, infants stopped crawling to sit 3–6 times per minute. Transitions from crawling to sitting frequently turned infants' bodies away from the direction of heading; subsequent transitions back to crawling were offset by as much as 180° from the original direction of heading. Apparently, body reorientations result from the biomechanics of transitioning between crawling and sitting. Findings indicate that sustained, linear crawling is likely an epiphenomenon of how gait is studied in standard paradigms. Postural transitions between crawling and sitting are ubiquitous and can represent a functional unit of action. These transitions and the accompanying body reorientations likely have cascading effects for infants' exploration, visual perception, and spatial cognition.     

Imitation among infants in a day-care center and the development of locomotion

To examine the relationship between imitation and locomotor development among peers during infancy, we observed free play in a class of infants in a day-care center over a one-year period. The analysis included 16 infants (mean age was 8.3 months (SD=2.3) at the beginning of the observation) and 5 caregivers. The longitudinal data were divided into the crawling, cruising, and walking periods, and the imitation of object manipulation that took place among the infants during each period was analyzed. With the development of locomotion, peer-to-peer imitation became frequent. Infants who had acquired the ability to walk demonstrated imitation more frequently in triadic interactions than in dyadic interactions. Imitation took place between infants, but it was often mediated by caregivers rather than directly between infants. The results suggest that the acquisition of locomotor skills is a link in a developmental cascade from motor development to infant peer interaction. However, it is reasonable to interpret the results as indicating that the development of locomotion does not directly affect infant interactions in isolation, but rather that walking increases both the sharing and manipulation of objects with caregivers and proximity to peers, and their combined effects form a cascade.     

See and be seen: Infant–caregiver social looking during locomotor free play

Face‐to‐face interaction between infants and their caregivers is a mainstay of developmental research. However, common laboratory paradigms for studying dyadic interaction oversimplify the act of looking at the partner's face by seating infants and caregivers face to face in stationary positions. In less constrained conditions when both partners are freely mobile, infants and caregivers must move their heads and bodies to look at each other. We hypothesized that face looking and mutual gaze for each member of the dyad would decrease with increased motor costs of looking. To test this hypothesis, 12‐month‐old crawling and walking infants and their parents wore head‐mounted eye trackers to record eye movements of each member of the dyad during locomotor free play in a large toy‐filled playroom. Findings revealed that increased motor costs decreased face looking and mutual gaze: Each partner looked less at the other's face when their own posture or the other's posture required more motor effort to gain visual access to the other's face. Caregivers mirrored infants' posture by spending more time down on the ground when infants were prone, perhaps to facilitate face looking. Infants looked more at toys than at their caregiver's face, but caregivers looked at their infant's face and at toys in equal amounts. Furthermore, infants looked less at toys and faces compared to studies that used stationary tasks, suggesting that the attentional demands differ in an unconstrained locomotor task. Taken together, findings indicate that ever‐changing motor constraints affect real‐life social looking.     

“Ghosts in the Nursery:” Infant sleep and sleep‐related cognitions of parents raised under communal sleeping arrangements

In an experiment of nature, a normal cohort of parents who were raised under communal sleeping arrangements (CSA) in Israeli kibbutzim are raising their infants at home under home‐based family sleeping arrangements. The present study focused on exploring the links between the early sleep experiences of CSA parents and their present sleep‐related beliefs and behaviors. In particular, the study assessed whether the cognitions of CSA parents regarding infant sleep differ from cognitions of parents who were raised under home‐based family sleeping arrangements. Furthermore, parental soothing methods and infant sleep patterns were compared. One hundred forty‐one families participated in this study. The children's ages ranged between 4.5 to 30 months. Parental cognitions were evaluated by two questionnaires. Infant sleep was assessed by a questionnaire and by daily parental reports. As expected, CSA parents were more likely than were control parents to: (a) interpret infant night wakings as a sign of distress and (b) actively soothe their infants at bedtime, co‐sleep with them, and report more night wakings of their infants. These findings support the hypothesis that early childhood sleep‐related experiences of parents (“Ghosts in the Nursery”) influence their parental sleep‐related cognitions that in turn affect infant sleep patterns.     

Learning to walk changes infants’ social interactions

The onset of crawling marks a motor, cognitive and social milestone. The present study investigated whether independent walking marks a second milestone for social behaviors. In Experiment 1, the social and exploratory behaviors of crawling infants were observed while crawling and in a baby-walker, resulting in no differences based on posture. In Experiment 2, the social behaviors of independently walking infants were compared to age-matched crawling infants in a baby-walker. Independently walking infants spent significantly more time interacting with the toys and with their mothers, and also made more vocalizations and more directed gestures compared to infants in the walker. Experiment 3 tracked infants’ social behaviors longitudinally across the transition from crawling and walking. Even when controlled for age, the transition to independent walking marked increased interaction time with mothers, as well as more sophisticated interactions, including directing mothers’ attention to particular objects. The results suggest a developmental progression linking social interactions with milestones in locomotor development.     

Crawling-onset age predicts visual cliff avoidance in infants

Two experiments are reported that tested the effects of crawling-onset age, the amount of crawling experience, and testing age on avoidance of the deep side of a visual cliff apparatus by human infants. In Experiment 1, 49 infants ranging in age from 7 to 13 mo. were tested on the visual cliff after 1 or 2 mo. of crawling experience. Discriminant analysis revealed that crawling-onset age, and not crawling experience, discriminated between those infants who crossed and those infants who avoided the apparent drop-off. Infants who crossed the deep side were infants with an early crawling-onset age. In Experiment 2, 40 infants were tested on a visual cliff apparatus, half at 9 and half at 12 mo. of age. Discriminant analysis again found that crawling-onset age discriminated between infants who crossed the infants who would not cross the deep side, whereas testing age alone did not. These results call into question the idea that experience crawling is critical in inducing visually guided avoidance behavior in infants. It is argued that the crawling-onset age effect occurs because crawling during the tactile phase of infancy interferes with later visual control of locomotion.     

婴儿运动经验与母婴社会性情绪互动行为的关系

本研究考察了个体早期自主位移运动——爬行经验与母婴社会性情绪互动的关系。对79名8、9个月婴儿的母亲进行访谈,结果发现,在8个月婴儿中,婴儿会爬与否对母婴社会性情绪互动行为有一定作用,但这种作用没有达到显著水平;在9个月时,婴儿是否会爬则对母婴社会性情绪互动行为有显著影响,表明爬行经验对母婴社会性情绪互动行为的影响存在累积效应与年龄特异性。     

Detection of the traversability of surfaces by crawling and walking infants

In four studies we investigated the perception of the affordance for traversal of a supporting surface. The surface presented was either rigid or deformable, and this property was specified either optically, haptically, or both. In Experiment 1A, crawling and walking infants were presented with two surfaces in succession: a standard surface that both looked and felt rigid and a deforming surface that both looked and felt nonrigid. Latency to initiate locomotion, duration of visual and haptic exploration, and displacement activity were coded from videotapes. Compared with the standard, the deforming surface elicited longer latency, more exploratory behavior, and more displacement in walkers, but not in crawlers, suggesting that typical mode of locomotion influences perceived traversability. These findings were replicated in Experiment 1B, in which the infant was presented with a dual walkway, forcing a choice between the two surfaces. Experiments 2, 3A and B, and 4A and B investigated the use of optical and haptic information in detecting traversability of rigid and nonrigid surfaces. Patterns of exploration varied with the information presented and differed for crawlers and walkers in the case of a deformable surface, as an affordance theory would predict.     

Sleep Architecture in Infants of Substance‐Abusing Mothers

This longitudinal, year‐long study compared sleep–wake state organization in two groups of infants–infants whose mothers abused substances during their pregnancies and nonexposed, typically developing, age‐matched comparison infants–to determine whether differences in sleep–wake state organization existed between the two groups. Seventeen infants of mothers who were participating in a parent–infant residential treatment program for substance abuse were enrolled. Their sleep–wake state organization over the first year of life was compared to that of 17 age‐matched comparison infants. The intent was to follow each infant on five occasions over the first year of life using established methods of time‐lapse videosomnography to record sleep–wake state organization; however, attrition in the substance‐abusing group was problematic. Some sleep–wake variables (i.e., Active Sleep%, Quiet Sleep%, Awake%, number of nighttime awakenings) were similar for both groups of infants at comparable ages across the first year. Total sleep time and the longest sustained sleep period (sleep continuity variables) differed significantly at some of the ages measured. Although overall sleep architecture appears highly resilient and well organized, some indications of sleep fragmentation and shortened nighttime sleep periods were observed in the substance‐exposed infants. More research is needed to explain why sleep‐continuity variables and not sleep‐state proportion variables differed between the two groups.     

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.     

Crawling is associated with more flexible memory retrieval by 9-month-old infants

In the present experiment, we used a deferred imitation paradigm to explore the effect of crawling on memory retrieval by 9-month-old human infants. Infants observed an experimenter demonstrate a single target action with a novel object and their ability to reproduce that action was assessed after a 24-hr delay. Some infants were tested with the demonstration stimulus in the demonstration context and some infants were tested with a different stimulus in a different context. Half of the infants in each test condition were crawling at the time of participation and half were not. Both crawling and non-crawling infants exhibited retention when tested with the demonstration stimulus in the demonstration context, but only infants who were crawling by 9 months of age exhibited retention when tested with a different stimulus in a different context. These findings demonstrate that the onset of independent locomotion is associated with more flexible memory retrieval during the first year of life.     

爬行经验与婴儿空间认知能力的发展

本研究采用“A非B”时间延搁测验对34名9-12个月缨儿的爬行经验与其空间认知能力发展的关系进行了研究。协方差分析表明,婴儿的爬行经验对其在“A非B”延搁任务中表现出来的空间认知能力有显著的主效应,而年龄的效应不明显;进一步分析显示,爬行经验7周以内的婴儿与爬行经验10周以上的婴儿空间认知能力发展水平差异显著。本研究说明,爬行经验与婴儿在“A非B”延搁任务上表现出来的空间认知能力发展有密切的关系。     

Sleep arrangements and maternal adaptation in infancy

Among the many decisions that parents make regarding child‐rearing practices, an important one involves sleep arrangements. Little is known about the relationship between chosen sleep arrangements, parents' adaptation to these choices, parental sleep quality, spousal support, and parental distress. Forty‐five mothers and fathers with infants 1 to 24 months old completed measures of parental attitudes and practices regarding sleep arrangements. Shared sleep with one's infant was associated with poorer parental adaptation to infant sleep disruption, and this was true even when parents endorsed the practice of sharing sleep with their infants. Among mothers, shared sleep and poorer adaptation to infant sleep were significantly associated with elevated depressive symptoms, poorer sleep quality, and spousal criticism directed to mothers about where the infant slept during the night. For mothers, criticism from their spouses about where the baby slept, mothers' sleep quality, and depressive symptoms mediated the link between sleep arrangements and maternal adaptation. Results emphasize the importance of taking into account individual differences in the quality of parents' adaptation to infant sleep behavior, a construct largely ignored in the child sleep literature to date, in understanding linkages between infant sleep quality and infant–parent outcomes.