Sitting skill and the emergence of arms‐free sitting affects the frequency of object looking and exploration

An update of the development of motor behavior

This primer describes research on the development of motor behavior. We focus on infancy when basic action systems are acquired-posture, locomotion, manual actions, and facial actions-and we adopt a developmental systems perspective to understand the causes and consequences of developmental change. Experience facilitates improvements in motor behavior and infants accumulate immense amounts of varied everyday experience with all the basic action systems. At every point in development, perception guides behavior by providing feedback about the results of just prior movements and information about what to do next. Across development, new motor behaviors provide new inputs for perception. Thus, motor development opens up new opportunities for acquiring knowledge and acting on the world, instigating cascades of developmental changes in perceptual, cognitive, and social domains. This article is categorized under: Cognitive Biology > Cognitive Development Psychology > Motor Skill and Performance Neuroscience > Development.

Early object skill supports growth in role-differentiated bimanual manipulation in infants

The ability to coordinate the hands together to act on objects where each hand does something different is known as role-differentiated bimanual manipulation (RDBM). This study investigated two motor skills that may support the development of RDBM: infants' early object skill and their early sitting skill. To evaluate these potential predictors of RDBM growth, 90 infants were examined in a lab-based longitudinal design over a 9-month period. Latent growth modeling was used to estimate RDBM growth trajectories over 9 to 14 months from infants' object and sitting skills at 6 months, controlling for infant's sex, mother's education, and family income. Higher object skill, controlling for sitting skill, was related to a higher increase in RDBM over time. Sitting did not predict infants' change in RDBM over time, controlling for object skill. The ability to manage multiple objects may support collaborative hand use by providing infants with opportunities to practice actions that will be needed later for RDBM. By comparison, sitting may free the hands in an unspecified manner for manipulation.

Focused attention as a new sitter: How do infants balance it all?

This study investigated the impact of postural control on infants' Focused Attention (FA). Study 1 examined whether and how sitting independently versus with support impacted 6- to 8-month-old infants' ability to focus attention during object exploration. FA measures did not depend on support condition. However, sitting experience was significantly negatively correlated with FA measures in the supported condition, suggesting that infants with more sitting experience performed fewer exploratory movements, possibly due to faster information processing ability compared to infants with less sitting experience. These unexpected findings prompted an exploration of more subtle looking behaviors during FA in Study 2-a case study of three infants who wore a head-mounted eye-tracker during an FA task. The ability to rapidly shift visual attention was key to gathering environmental information useful for problem solving-an interpretation that is supported by prior findings of the relationship between fast looks and faster information processing.

A pilot randomised controlled trial of ride-on cars and postural combinations of standing and sitting for mobility and social function in toddlers with motor delays

PURPOSE

Locomotor experiences in upright postures are essential for developing toddlers' mobility and social functions. This pilot randomised controlled trial aimed to examine the effectiveness of using a modified ride-on car (ROC) with postural combinations of standing and sitting on mobility and social function in toddlers with motor delays.

MATERIALS AND METHODS

Nineteen participants aged 1-3 years with mild, moderate or severe motor delays were randomly assigned to four ROC groups. The ROC groups had different combinations of standing and sitting, namely standing for 70 min (ROC-Stand70, five participants), standing for 45 min (ROC-Stand45, four participants), standing for 25 min (ROC-Stand25, five participants) and sitting for 70 min (ROC-Sit70, five participants). All participants participated in 2-h sessions twice a week for 12 weeks. The Pediatric Evaluation of Disability Inventory, Goal Attainment Scaling and Bayley-III tests were administered before and after the intervention, and after 12 weeks of follow-up. A mixed-model analysis of variance was used to compare inter- and intra-group differences. This trial was registered at ClinicalTrials.gov (NCT03707405).

RESULTS

All groups showed significantly improved mobility, social function and goal achievement at the post-test (p < .001). However, no significant changes were observed in Bayley scores.

CONCLUSIONS

Combining physical and social environmental modifications with active exploration is crucial for early power mobility training in toddlers with motor delays. To enhance the robustness and generalisability of our findings, future studies should include larger sample sizes, consider variations in motor delays, and measure energy expenditure during the intervention.Implications for rehabilitationProviding active exploratory experience using ride-on cars (ROCs) with various postural combinations can improve a child's mobility.The ROC training with various postural combinations can improve social function, and the degree of improvement may depend on the severity of motor delays.Setting goals with caregivers and incorporating their roles in the training process can empower them to interact with children more frequently and actively.

Opportunities for learning and social interaction in infant sitting: Effects of sitting support, sitting skill, and gross motor delay

The development of independent sitting changes everyday opportunities for learning and has cascading effects on cognitive and language development. Prior to independent sitting, infants experience the sitting position with physical support from caregivers. Why does supported sitting not provide the same input for learning that is experienced in independent sitting? This question is especially relevant for infants with gross motor delay, who require support in sitting for many months after typically developing infants sit independently. We observed infants with typical development (n = 34, ages 4-7 months) and infants with gross motor delay (n = 128, ages 7-16 months) in early stages of sitting development, and their caregivers, in a dyadic play observation. We predicted that infants who required caregiver support for sitting would spend more time facing away from the caregiver and less time contacting objects than infants who could sit independently. We also predicted that caregivers of supported sitters would spend less time contacting objects because their hands would be full supporting their infants. Our first two hypotheses were confirmed; however, caregivers spent surprisingly little time using both hands to provide support, and caregivers of supported sitters spent more time contacting objects than caregivers of independent sitters. Similar patterns were seen in the group of typically developing infants and the infants with motor delay. Our findings suggest that independent sitting and supported sitting provide qualitatively distinct experiences with different implications for social interaction and learning opportunities. HIGHLIGHTS: During seated free play, supported sitters spent more time facing away from their caregivers and less time handling objects than independent sitters. Caregivers who spent more time supporting infants with both hands spent less time handling objects; however, caregivers mostly supported infants with one or no hands. A continuous measure of sitting skill did not uniquely contribute to these behaviors beyond the effect of binary sitting support (supported vs. independent sitter). The pattern of results was similar for typically developing infants and infants with gross motor delay, despite differences in age.

Dynamics of the dyad: How mothers and infants co-construct interaction spaces during object play

Studies of dyadic interaction often examine infants' social exchanges with their caregivers in settings that constrain their physical properties (e.g., infant posture, fixed seating location for infants and adults). Methodological decisions about the physical arrangements of interaction, however, may limit our ability to understand how posture and position shape them. Here we focused on these embodied properties of dyadic interaction in the context of object play. We followed 30 mother-infant dyads across the first year of life (at 3, 6, 9, and 12 months) and observed them during 5 min of play with a standard set of toys. Using an interval-based coding system, we measured developmental change in infant posture, how mothers and infants positioned themselves relative to one another, and how they populated interaction spaces with objects. Results showed that mother-infant dyads co-constructed interaction spaces and that the contributions of each partner changed across development. Dyads progressively adopted a broader spatial co-orientation during play (e.g., positioned at right angles) across the first year. Moreover, advances in infants' postural skills, particularly increases in the use of independent sitting in real time, uniquely predicted change in dyadic co-orientation and infants' actions with objects, independent of age. Taken together, we show that the embodied properties of dyadic object play help determine how interactions are physically organized and unfold, both in real time and across the first year of life.

Object Permanence and the Relationship to Sitting Development in Infants With Motor Delays

PURPOSE

This study examines object permanence development in infants with motor delays (MD) compared with infants with typical development (TD) and in relation to sitting skill.

METHODS

Fifty-six infants with MD (mean age = 10 months) and 36 with TD (mean age = 5.7 months) were assessed at baseline and then at 1.5, 3, and 6 months postbaseline. A scale was developed to measure object permanence (Object Permanence Scale [OPS]), and the Gross Motor Function Measure sitting subsection (GMFM-SS), and the Bayley Scales of Infant and Toddler Development, 3rd Edition (Bayley-III) were administered.

RESULTS

Interrater reliability of the OPS was excellent and correlation between the OPS and Bayley-III cognitive scores was moderately positive. Compared with TD, infants with MD were delayed in development of object permanence but demonstrated increased understanding over time and as sitting skills improved.

CONCLUSION

In children with MD, object permanence, as quantified by the OPS, emerges in conjunction with sitting skill.

Infants exploring objects: A cascades perspective

Infants spend much of their time exploring objects (Herzberg et al., 2021), and object exploration is linked to learning and development in various domains (e.g., social, cognitive, motor). But how does exploration develop in the first place, and how, exactly, does exploration promote learning? One way to approach these process-oriented questions is with a developmental cascades perspective, which holds that new skills emerge from earlier-developing ones and that various interactions with people and objects accumulate over time to influence multiple domains of development (Masten & Cicchetti, 2010). In this chapter, we describe object exploration from a developmental cascades perspective. In Section 2, we describe typical and atypical trajectories of exploration behaviors, noting how these behaviors emerge from earlier-developing cognitive and motor skills. In Section 3, we discuss how object exploration opens the door for new types of learning opportunities. In Section 4, we discuss early experiences that may shape the development of object exploration. Altogether, we aim to convey that new developments in exploration skills are extensions of earlier-developing skills, and that seemingly insignificant exploratory behaviors (e.g., shaking a rattle) may result in numerous and varied consequences for the developing infant.

Posture Matters: Object Manipulation During the Transition to Arms-Free Sitting in Infants at Elevated vs. Typical Likelihood for Autism Spectrum Disorder

Aims: We investigated how infants grasped and transferred toys over a four-week period as they transitioned to arms-free sitting. We compared object manipulation in infants with typical likelihood (TL) and elevated likelihood (EL) for autism spectrum disorder (ASD) as they sat with vs. without support.Methods: Eighteen infants (7 EL; 11 TL; 5-8 months of age at the start of the study) were observed during three sessions at home across the transition to arms-free sitting. At each session, toys were presented to the infants in two different postures: sitting with support from a boppy pillow and sitting independently. Mean percentage of time spent grasping and rates of transferring objects between two hands were calculated for each infant at each session.Results: Both grasping time and transfer rate increased across the transition to arms-free sitting. EL infants, but not TL infants, spent significantly less time grasping toys when sitting independently than when sitting with support.Conclusions: Sitting plays a significant role in the development of object manipulation skills. Our results reveal a need to examine object manipulation skills in multiple posture contexts, especially in infants who exhibit motor delays.

Early motor skills predict the developmental trajectory of problem solving in young children with motor delays

INTRODUCTION

The purpose of this study was to quantify the relationship between early motor skills, such as sitting, and the development of problem-solving skills in children with motor delays.

METHODS

Motor (Gross Motor Function Measure) and problem-solving (Assessment of Problem-Solving in Play) skills of 134 children 7-16 months adjusted age at baseline with motor delay were assessed up to 5 times over 12 months. Participants were divided into two groups: mild and significant motor delay.

RESULTS

Motor and problem-solving scores had large (r's = 0.53-0.67) and statistically significant (p's > .01) correlations at all visits. Baseline motor skills predicted baseline and change in problem solving over time. The associations between motor and problem-solving skills were moderated by level of motor delay, with children with significant motor delay generally having stronger associations compared to those with mild motor delay.

CONCLUSIONS

These findings suggest that overall baseline motor skills are predictive of current and future development of problem-solving skills and that children with significant motor delay have a stronger and more stable association between motor and problem-solving skills over time. This highlights that children with motor delays are at risk for secondary delays in problem solving, and this risk increases as degree of motor delay increases.

Does late preterm birth impact trunk control and early reaching behavior?

The aims of the study were to 1) verify the level of trunk control longitudinally and reaching behavior while sitting in two positions in late preterm (LPT) and full-term (FT) infants, 2) determine whether the level of trunk control relates to reaching outcomes. Twenty LPT infants and 36 infants born FT were assessed via three in-lab visits: at 6, 7, and 8 months. At each visit, the Segmental Assessment of Trunk Control (SATCo) and reaching assessment were performed, where the infants were positioned sitting in the ring and at 90° of flexion of hips, knees, and ankles. Accurate manual support to the trunk was provided in each visit. LPT infants presented a lower level of trunk control over time. LPT infants presented a higher percentage of unimanual reaches and successful grasping at 7 months' visit, and a higher number of reaches at 8 months' visit compared to FT infants. The sitting positions did not influence reaching performance. The level of trunk control relates to functional reaching strategies only in FT infants. This study might provide insights for clinicians for understanding the level of trunk control, the importance of reaching behaviors for exploration, and considering these behaviors as strategies for intervention.

Physical therapy interventions to improve sitting ability in children with or at-risk for cerebral palsy: a systematic review and meta-analysis

AIM

To conduct a systematic review and meta-analysis on the effectiveness of physical therapy interventions to improve sitting ability in young children with or at risk for cerebral palsy (CP).

METHOD

A systematic literature search was performed using five databases. Study selection criteria were randomized controlled trials published in English on physical therapy interventions targeting sitting, reporting developmental or functional sitting outcomes, and focused on young children with or at risk for CP (mean age ≤5y). Risk of bias (ROB) was assessed using the Cochrane ROB 2.0 tool.

RESULTS

Twelve unique studies met the inclusion criteria and were categorized into one of two categories: (1) comparison of two physical therapy interventions or (2) physical therapy plus adjunct versus physical therapy alone. The combined pooled effect size (g) for the 10 studies included in meta-analysis was large (g=0.78) but non-significant. Pooled effect for category 1 was small (g=-0.06) and non-significant. Interventions in category 2 showed a large and significant effect (g=1.90, p=0.022).

INTERPRETATION

There is a lack of strong evidence for physical therapy interventions targeting sitting in young children with or at-risk for CP due to limitations in methodological rigor and sample sizes. Components of impairment remediation combined with functional balance training should be explored to improve sitting in children diagnosed with CP. Given the benefits of early achievement of sitting, strong evidence-based research is needed.

WHAT THIS PAPER ADDS

Strong evidence is lacking for physical therapy interventions to improve sitting ability in young children with/at risk for cerebral palsy (CP). Kinesio-taping may be an effective adjunct to conventional physical therapy in improving sitting ability in children with spastic bilateral CP. Task-specific, intensive, and child-initiated intervention components show promise for improving sitting in young infants at risk for CP.

Measuring Early Problem-Solving in Young Children with Motor Delays: A Validation Study

AIM

There is a lack of evidence-based tools for measuring problem-solving in young children with motor delays. The purpose of this study was to evaluate the construct validity and responsiveness of the Assessment of Problem-Solving in Play.

METHODS

125 young children (10.72, SD 2.62 months) with mild, moderate, and severe motor delays were assessed with the Bayley Scales of Infant and Toddler Development, Third Edition Cognitive Scale and the Assessment of Problem-Solving in Play up to 4 times over 12 months. The baseline and change over time assessment scores were compared.

RESULTS

The Assessment of Problem-Solving in Play was strongly, positively correlated with the Bayley Scales of Infant and Toddler Development, Third Edition Cognitive Scale raw scores at baseline (r=.83, p<.001) and for changes in scores across time (r=.64, p<.001). On average, participants demonstrated positive change in problem-solving scores across time. Participants with severe motor delay scored lower at baseline and changed less as compared to other participants.

CONCLUSIONS

Results provide evidence for the construct validity and responsiveness of the Assessment of Problem-Solving in Play scores in quantifying problem-solving in young children with motor delays 7-27 months of age.

Object exploration during the transition to sitting: A study of infants at heightened risk for autism spectrum disorder

Learning to sit promotes infants' object exploration because it offers increased access to objects and an improved position for exploration (e.g., ). Infants at heightened risk (HR) for autism spectrum disorder (ASD) exhibit delays in sitting and differences in object exploration. However, little is known about the association between sitting and object exploration among HR infants. We examined changes in object exploration as HR infants (N = 19) and comparison infants with no family history of ASD (Low Risk; LR; N = 23) gained experience sitting independently. Infants were observed monthly from 2.5 months until 1 month after the onset of independent sitting. At 12, 18, 24, and 36 months, infants completed standardized developmental assessments, and HR infants were assessed for ASD symptoms at 36 months. Although HR infants began sitting later than LR infants, both groups increased time spent grasping, shaking, banging, and mouthing objects as they gained sitting experience. Groups only differed in time spent actively mouthing objects, with LR infants showing a greater increase in active mouthing than HR infants. Findings suggest that HR infants experience a similar progression of object exploration across sitting development, but on a delayed time scale.

Do 6-Month Motor Skills Have Cascading Effects on 12-Month Motor and Cognitive Development in Extremely Preterm and Full-Term Infants?

In this study, we analyzed whether 6-month gross and fine motor skills were related to 12-month gross and fine motor skills and cognitive development, controlling for 6-month cognitive skills, and neonatal status (extremely low gestational age ELGA ≤ 28 weeks vs. full-term FT ≥ 37 weeks). We also investigated, at 6 months, predictive indexes for motor and cognitive delay at 12-months. We assessed 40 infants (20 ELGA and 20 FT) at 6 and 12 months (corrected age for the ELGA infants). Six-month gross motor skills were related to 12-month gross motor, fine motor, and cognitive skills and predicted 12-month gross motor delay. Six-month cognitive skills explained an additional amount of variance of 12-month gross motor skills, whereas neonatal status explained an additional amount of variance of 12-month cognitive skills. Considering the intradomain and cross-domain cascading effects of early gross motor skills on later motor and cognitive development, these skills should be repeatedly assessed in ELGA infants in the first year of life for early identification of infants with delayed gross motor skills and implementation of customized interventions.

Is Segmental Trunk Control Related to Gross Motor Performance in Healthy Preterm and Full-Term Infants?

The authors' aim was to verify the correlation between segmental trunk control and gross motor performance in healthy preterm (PT) and full-term (FT) infants aged 6 and 7 months and to verify if there are differences between groups. All infants were assessed at 6 and 7 months by means of Segmental Assessment of Trunk Control (SATCo) to identify the exact level of segmental trunk control and Alberta Infant Motor Scale (AIMS) to measure gross motor performance. A significant correlation between segmental trunk control and gross motor performance was found in healthy PT infants at 7 months and FT infants at 6 months. PT infants showed a delay on segmental trunk control at 6 and 7 months and in supported standing posture at 6 months compared with FT infants. Segmental trunk control and gross motor performance showed an important relationship in healthy PT and FT infants, mainly in sitting posture.