Posture and gaze in early mother–infant communication: synchronization of developmental trajectories

Weekly laboratory observations of free play for 13 middle-income mother–infant dyads, from 1 to 6 months of age, were used to study the synchronization of developmental trajectories between infant postural position and gaze direction. Mothers sat in a straight-backed chair while holding infants on their laps and were free to adjust the infant’s posture. Postural position was coded as upright (supported sitting or standing on the mother’s lap) or other (lying, cradling, or being held close to mother). Gaze was coded as either at mother’s face or away. The age of onset of visually guided reaching was also assessed. Results show that there were longer durations of gazing away when the infant was in an upright position. Over the 5 month period of observation, the dyads began with a pattern of non-upright positions accompanied by gaze at mother. Contrary to previous predictions, the developmental shift in the first 6 months from exclusive gazing at mother’s face to gazing away from mother was not synchronized with the development of reaching, but rather with changes in the infant’s posture to more upright positions. The possible role of postural position in fostering positive emotional communication is discussed.     

Moving into tummy time,together: Touch and transitions aid parent confidence and infant development

“Back to sleep” messages can reduce prone practice for infants, with potential for motor delay and cranial deformation. Despite recommendations for “tummy time,” young infants fuss in prone, and parents report uncertainty about how to help infants tolerate prone positioning. We hypothesized that a Child'Space Method lesson, teaching proprioceptive touch and transitions to prone, would facilitate prone tolerance, parent behavioral support, and parent self-efficacy. This randomized study recruited parents (N = 37) of 2- to 5-month-old infants. On two visits, parents answered questions about infant behavior and parent experience, and played with their infant. Lesson group parents had the lesson following the first free play. One week later, lesson parents reported that infants tolerated more prone time and that parents showed more supportive behaviors in bringing infant to prone, as compared to waiting parents. Lesson parents’ efficacy, and infant behavior during play, trended in the hypothesized direction. The study demonstrated how a lesson in preparatory touch, and gradual transitions, promoted infant prone tolerance and also parent support of rolling, side-lying, and prone positioning. The lesson could be incorporated in parent education and early pediatric visits, helping infants and parents negotiate the prone challenge and setting the stage for further parent support of infant development.     

Are postural adjustments during reaching related to walking development in typically developing infants and infants at risk of cerebral palsy?

BackgroundIn typical development, postural adjustments during reaching change in the second half of infancy, including increasing rates of direction-specific adjustments. These changes are absent or different in infants at risk of cerebral palsy (CP). To discover whether these changes are related to acquisition of independent walking, we studied postural adjustments during reaching in infants before and after they learned to walk.MethodsTen typically developing (TD) infants and 11 infants at very high risk (VHR) of CP were assessed before and after they learned to walk. Reaching movements were elicited during supported sitting, while surface electromyography was recorded of arm, neck, and trunk muscles. Percentages of direction-specific adjustments (first level of control), and recruitment patterns and anticipatory activation (second level of control) were calculated.ResultsIn both groups, postural adjustments during reaching were similar before and after acquisition of independent walking. Direction-specificity increased with age in typically developing infants but not in VHR-infants.ConclusionIncreasing age rather than the transition to independent walking is associated with increasing direction-specificity of TD-infants during reaching while sitting, while infants at very high risk of CP show no increase in direction-specificity, suggesting that they gradually grow into a postural deficit.     

Right–left approach and reaching arm movements of 4-month infants in free and constrained conditions

Recent theories on the evolution of language (e.g. Corballis, 2009) emphazise the interest of early manifestations of manual laterality and manual specialization in human infants. In the present study, left- and right-hand movements towards a midline object were observed in 24 infants aged 4 months in a constrained condition, in which the hands were maintained closed, and in a free condition. A left-hand dominance for approach movements without contact with the object, and a right-hand dominance for reaching movements with object contact was observed in the free condition. In the constrained condition reaching movements of the right hand decreased dramatically. These results are interpreted as strong evidence of manual specialization in 4-month olds, with approach movements having a localization role and reaching movements announcing future right-hand dominance for prehension and object manipulation.     

Self-Sitting and Reaching in 5- to 8-Month-Old Infants: The Impact of Posture and Its Development on Early Eye-Hand Coordination

The relation between progress in the control of posture (i.e., the achievement of self-sitting posture) and the developmental transition from two-handed to one-handed engagement in infant reaching was investigated. Two groups of 5- to 8-month-old infants, who were either able or yet unable to sit on their own, were videotaped while they reached for objects in four different posture conditions that provided varying amounts of body support. Videotapes of infant reaches were microanalyzed to determine the relative engagement of both hands during reaches. Results demonstrate the interaction between postural development and the morphology of infant reaching. Nonsitting infants displayed symmetrical and synergistic engagement of both arms and hands while reaching in all but the seated posture condition. Sitting infants, by contrast, showed asymmetrical and lateralized (one-handed) reaches in all posture conditions. Results also show that, aside from posture, the perceived spatial arrangement of the object display is a determinant of infant reaching. Combined, these results are discussed as evidence for the interaction between postural and perceptual development in the control of early eye-hand coordination.     

Self-sitting and reaching in 5- to 8-month-old infants: the impact of posture and its development on early eye-hand coordination

The relation between progress in the control of posture (i.e., the achievement of self-sitting posture) and the developmental transition from two-handed to one-handed engagement in infant reaching was investigated. Two groups of 5- to 8-month-old infants, who were either able or yet unable to sit on their own, were videotaped while they reached for objects in four different posture conditions that provided varying amounts of body support. Videotapes of infant reaches were microanalyzed to determine the relative engagement of both hands during reaches. Results demonstrate the interaction between postural development and the morphology of infant reaching. Nonsitting infants displayed symmetrical and synergistic engagement of both arms and hands while reaching in all but the seated posture condition. Sitting infants, by contrast, showed asymmetrical and lateralized (one-handed) reaches in all posture conditions. Results also show that, aside from posture, the perceived spatial arrangement of the object display is a determinant of infant reaching. Combined, these results are discussed as evidence for the interaction between postural and perceptual development in the control of early eye-hand coordination.     

Looking is not enough: Multimodal attention supports the real-time learning of new words

Most research on early language learning focuses on the objects that infants see and the words they hear in their daily lives, although growing evidence suggests that motor development is also closely tied to language development. To study the real-time behaviors required for learning new words during free-flowing toy play, we measured infants’ visual attention and manual actions on to-be-learned toys. Parents and 12-to-26-month-old infants wore wireless head-mounted eye trackers, allowing them to move freely around a home-like lab environment. After the play session, infants were tested on their knowledge of object-label mappings. We found that how often parents named objects during play did not predict learning, but instead, it was infants’ attention during and around a labeling utterance that predicted whether an object-label mapping was learned. More specifically, we found that infant visual attention alone did not predict word learning. Instead, coordinated, multimodal attention–when infants’ hands and eyes were attending to the same object–predicted word learning. Our results implicate a causal pathway through which infants’ bodily actions play a critical role in early word learning.     

Intentional action processing across the transition to crawling: Does the experience of self-locomotion impact infants’ understanding of intentional actions?

Motor developmental milestones in infancy, such as the transition to self-locomotion, have cascading implications for infants’ social and cognitive development. The current studies aimed to add to this literature by exploring whether and how crawling experience impacts a key social-cognitive milestone achieved in infancy: the development of intentional action understanding. Study 1 used a cross-sectional, age-held-constant design to examine whether locomotor (n = 36) and prelocomotor (n = 36) infants differ in their ability to process a failed intentional reaching action. Study 2 (n = 124) further probed this question by assessing how variability in locomotor infants’ experience maps onto variability in their failed intentional action understanding. Both studies also assessed infants’ tendency to engage in triadic interactions to shed light on whether self-locomotion impacts intentional action understanding directly or indirectly via changes in infants’ interactions with social partners. Altogether, results showed no evidence for the role of self-locomotion in the development of intentional action understanding. Locomotor and prelocomotor infants did not differ in their failed action understanding or levels of triadic engagement (Study 1) and individual differences in days of crawling experience, propensity to crawl during play, and maximum crawling speed failed to predict infants’ intentional action understanding or triadic engagement (Study 2). Explanations for these null findings and alternative influences on the development of intentional action understanding are considered.     

Community Storytelling Network,Neighborhood Context,and Civic Engagement: A Multilevel Approach

From a communication infrastructure theory perspective, the current study examined individuals’ civic engagement (neighborhood belonging, collective efficacy, and civic participation) as influenced by 2 multilevel components of the communication infrastructure—an integrated connectedness to a storytelling network (ICSN) and the residential context—focusing on ethnic heterogeneity and residential stability. Our multilevel analyses show that ICSN is the most important individual‐level factor in civic engagement—neighborhood belonging, collective efficacy, and civic participation—after controlling for other individual‐level and neighborhood‐level factors. In both ethnically homogeneous and heterogeneous areas and in both stable and unstable areas, ICSN is an important factor in civic engagement. As contextual factors, residential stability positively affects neighborhood belonging and collective efficacy, and ethnic heterogeneity is negatively related to collective efficacy. Our data do not show any direct contextual effects of residential stability or ethnic heterogeneity on civic participation. However, our HLM analysis showed that the relative importance of ICSN for the likelihood of participation in civic activities is significantly higher in unstable or ethnically heterogeneous areas than in stable or ethnically homogeneous areas.     

Paw preference is not affected by postural demand in a nonprimate mammal (Felis silvestris catus)

Previously, it has been thought that handedness is unique to humans. Recently, it has been found that hand or paw preferences are common among a variety of vertebrate species. Different models have been put forth to describe the evolution of primate handedness. In this study we aimed to explore whether these models can also be used to predict manual laterality in nonprimate mammalian groups. The cat (Felis silvestris catus) is a good nonprimate model for manual laterality, as cats frequently use paws to catch and hold prey. Cats were exposed to two standardized manual laterality tasks, differing in postural demand. Subjects (N = 28) were forced to use either a stable or unstable body posture (i.e., sitting or standing vs. vertical clinging) to extract food items from a plastic box attached at two different heights. We revealed that cats exhibited paw preferences at an individual level with about 40% left, 30% right, 30% nonlateralized subjects. Postural demand was linked to task difficulty: the unstable body posture was found to be significantly more difficult than the stable body posture. However, these differences in postural demand and task difficulty did not lead to differences in direction or strength of paw preference. Findings suggested that nonprimate mammals differ from primates in their sensitivity to task related factors, such as postural demand. Results coincide with those of some prosimians, providing support for the hypothesis that postural demand and the associated task complexity became influencing factors on manual laterality in the course of primate evolution.     

Infants return to two-handed reaching when they are learning to walk

The authors examined whether infants of about 1 year return to 2-handed reaching when they begin to walk independently. Infants (N = 9) were followed longitudinally before, during, and after their transition to upright locomotion. Every week, the infants' reaching responses and patterns of interlimb coordination were screened in 3 tasks involving different adaptive reaching responses. Before the onset of upright locomotion, the infants responded to each task adaptively. Following walking onset, they increased their rate of 2-handed responses in all tasks. The 2-handed responses declined when the infants gained better balance control. The results suggest that infants' return to 2-handed reaching is experience dependent. Those findings are discussed in terms of the integration of new developing motor skills into existing cognitive and motor repertoires.     

Origins of the human pointing gesture: a training study

Despite its importance in the development of children’s skills of social cognition and communication, very little is known about the ontogenetic origins of the pointing gesture. We report a training study in which mothers gave children one month of extra daily experience with pointing as compared with a control group who had extra experience with musical activities. One hundred and two infants of 9, 10, or 11 months of age were seen at the beginning, middle, and end of this one‐month period and tested for declarative pointing and gaze following. Infants’ability to point with the index finger at the end of the study was not affected by the training but was instead predicted by infants’ prior ability to follow the gaze direction of an adult. The frequency with which infants pointed indexically was also affected by infant gaze following ability and, in addition, by maternal pointing frequency in free play, but not by training. In contrast, infants’ ability to monitor their partner’s gaze when pointing, and the frequency with which they did so, was affected by both training and maternal pointing frequency in free play. These results suggest that prior social cognitive advances, rather than adult socialization of pointing per se, determine the developmental onset of indexical pointing, but socialization processes such as imitation and adult shaping subsequently affect both infants’ ability to monitor their interlocutor’s gaze while they point and how frequently infants choose to point.     

How do deaf infants attain first signs?

In this study the development and alternation of nonreferential gestures were examined longitudinally in terms of the acquisition of Japanese sign language. Parent–child free‐play sessions in their home were videotaped at every monthly visit. Hand activities produced by two deaf infants of deaf parents are described and analyzed. Nonreferential gestures were observed frequently just before the occurrences of the first signs. They consisted of many rhythmic and repetitious movements. Nonreferential gestures became more complex and the number of them also increased as infants grew up. The comparison of nonreferential gestures and first signs revealed the continuity between them in terms of movements. In conclusion, nonreferential gestures are equivalent to a manual analog of vocal babbling.     

Unweighting infants reveals hidden motor skills

We investigated the role of rate limiting factors in development using walking as a model system. The achievement of bipedal posture and locomotion are among the most significant achievements in an infant's first year, with poor balance and weak muscles long proposed as the rate limiting factors. Compensating for either may reveal upright motor skill that has not yet emerged in the infant's natural repertoire. To probe this question, we unweighted prewalking infants and measured their performance in various standing and walking behaviors while unweighted compared to baseline. Our secondary objective was to determine if the influence of unweighting was related to infants’ locomotor experience. Infants stood unsupported for longer durations with 20% or 40% unweighting. Infants took more independent steps and more steps with one hand held with 40% unweighting. No differences in transition to/from standing were observed. Locomotor experience was related to the influence of unweighting during cruising and walking with a push toy. This is the first report of more advanced motor skills—longer periods of unsupported standing and the emergence of independent walking—revealed by unweighting infants. We interpret our observations to suggest that the refinement of motor control needed to support bipedal posture and locomotion precedes the functional emergence of these skills in infants. In other words, the musculoskeletal components required for walking are slower to develop than the neurological factors – and consequently may be the rate limiters. We further suggest that training regimens including unweighting should be explored in infants with motor delays.     

The cost of simplifying complex developmental phenomena: a new perspective on learning to walk

Researchers can study complex developmental phenomena with all the inherent noise and complexity or simplify behaviors to hone in on the essential aspects of a phenomenon. We used the development of walking as a model system to compare the costs and benefits of simplifying a complex, noisy behavior. Traditionally, researchers simplify infant walking by recording gait measures as infants take continuous, forward steps along straight paths. Here, we compared the traditional straight‐path task with spontaneous walking during 20 minutes of free play in 97 infants (10.75–19.99 months of age). We recorded infants’ footfalls on an instrumented floor to calculate gait measures in the straight‐path and free‐play tasks. In addition, we scored videos for other critical aspects of spontaneous walking—steps per bout, shape of walking path, and step direction. Studying infant walking during free play incurred no cost compared with the straight‐path task, but considerable benefits. Straight‐path gait was highly correlated with spontaneous gait and both sets of measures improved with walking age, validating use of the straight‐path task as an index of development. However, a large proportion of free‐play bouts were too short to permit standard gait measures, and most bouts were curved with omnidirectional steps. The high prevalence of these “non‐canonical” bouts was constant over development. We propose that a focus on spontaneous walking, the phenomenon we ostensibly wish to explain, yields important insights into the problems infants solve while learning to walk. Other areas of developmental research may also benefit from retaining the complexity of complex phenomena.     

Two steps forward and one back: Learning to walk affects infants' sitting posture

The transition from sitting to walking is a major motor milestone for the developing postural system. This study examined whether this transition to walking impacts the previously established posture (i.e., sitting). Nine infants were examined monthly from sitting onset until 9 months post-walking. Infants sat on a saddle-shape chair either independently or with their right hand touching a stationary contact surface. Postural sway was measured by sway amplitude, variability, area, and velocity of the center of pressure trajectory. The results showed that for all the postural measures in the no-touch condition, a peak before or at walk onset was observed in all the infants. At the transition age, when peak sway occurred, infants' postural sway measures were significantly greater than at any other age. Further, infants' postural sway was attenuated by touch only at this transition. We suggest that this transient disruption in sitting posture results from a process involving re-calibration of an internal model for the sensorimotor control of posture so as to accommodate the newly emerging bipedal behavior of independent walking.     

REARRANGING NATURALLY OCCURRING CONTINGENCIES TO INCREASE DESIRABLE BEHAVIOR IN A TODDLER CLASSROOM

Toddlers often display problem behavior during transitions. We rearranged naturally occurring events in a toddler classroom to promote more desirable classroom behavior during transitions to meals. In the intervention condition, teachers transitioned each child to meals only when that child was seated on a play mat (a requisite for engagement in teacher‐led play activities). In the reversal condition, teachers selected each child to transition when that child was by the barrier to the meal area (a practice commonly observed under natural conditions). The intervention increased the mean percentage of intervals when children were on the play mat and decreased the percentage of intervals when children were by the barrier. Individual child data show positive outcomes for five of six children. Results are discussed in terms of the positive effects of small manipulations to existing contingencies on classroom behavior as well as their potential influence on the adoptability of classroom interventions. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of movement distance,duration, velocity,and type on action prediction in 12-month-olds

The goal of the present study was to test the influence of the spatial and temporal dynamics of observed manual actions on infants’ action prediction. Twelve-month-old infants were presented with reach-and-transport actions performed by a human agent. Movement distance, duration, and – resulting from the two – movement velocity were systematically varied. Action prediction was measured via the latency of gaze arrival at target in relation to agent’s hand. The results showed a general effect of all parameters on the infants’ perception of goal-directed actions: Infants were more likely to predict the action goal the longer the movement distance was, the longer the movement duration was, and the slower the movement velocity was. In addition, they were more likely to predict the goal of a reaching than a transport action. The present findings extent previous findings by showing that infants are not only sensitive to differences in distances, durations, and velocities at early age but that these factors have a strong impact on the prediction of the goal of observed actions.     

The role of locomotor posture and experience on handedness and footedness in infancy

This research examined the development of handedness and footedness in infancy. We measured footedness by documenting the limb infants used to "lead-out" as they crawled or walked down a path several times. We measured handedness by documenting the hand infants used to reach for a goal at the end of each trial. Study 1 showed that locomotor skill affects limb lateralization preferences and that most 13-month-old infants demonstrated a side preference for reaching and leading out "in the moment." Study 2 longitudinally examined the developmental trajectories of handedness and footedness as they related to locomotor posture and experience. The findings suggest high variability in the developmental trajectory of footedness, with frequent fluctuation between side preferences. The developmental trajectory of handedness was more stable over the transition between locomotor milestones. The transition between crawling and walking decreased the proportion of infants demonstrating side preferences for leading out and the onset of walking decreased the proportion of infants demonstrating side preferences for reaching. These findings demonstrate the importance of making behavioral observations at multiple time scales to understand underlying developmental trajectories, specifically the stability or instability of the motor system associated with the acquisition of new motor abilities.     

Let’s get it together: Infants generate visual predictions based on collaborative goals

Infants engage in social interactions that include multiple partners from very early in development. A growing body of research shows that infants visually predict the outcomes of an individual’s intentional actions, such as a person reaching towards an object (e.g., Krogh-Jespersen & Woodward, 2014), and even show sophistication in their predictions regarding failed actions (e.g., Brandone, Horwitz, Aslin, & Wellman, 2014). Less is known about infants’ understanding of actions involving more than one individual (e.g., collaborative actions), which require representing each partners’ actions in light of the shared goal. Using eye-tracking, Study 1 examined whether 14-month-old infants visually predict the actions of an individual based on her previously shared goal. Infants viewed videos of two women engaged in either a collaborative or noncollaborative interaction. At test, only one woman was present and infants’ visual predictions regarding her future actions were measured. Fourteen-month-olds anticipated an individual’s future actions based on her past collaborative behavior. Study 2 revealed that 11-month-old infants only visually predict higher-order shared goals after engaging in a collaborative intervention. Together, our results indicate that by the second year after birth, infants perceive others’ collaborative actions as structured by shared goals and that active engagement in collaboration strengthens this understanding in young infants.