Sleight of hand: role-differentiated bimanual manipulation speed across infancy.

Role-differentiated bimanual manipulation (RDBM) is a complex behaviour requiring the complementary movement of two hands to achieve a common goal. We investigated the relation of RDBM speed (time to complete a successful RDBM) with a hand preference for acquiring objects (early right, late right, left, no preference), toy type (simple/difficult), age (9-14 months), and hand (right/left) used to perform the RDBM. Changes in RDBM speed across age were examined across different hand preference groups for RDBMs performed on simple toys using the right hand. The analysis revealed that early-right preference infants had a steeper slope than the no preference/left-preference infants. The same was true for right-preference infants (early- and late-) for RDBMs performed on difficult toys using the right hand. A mixed ANOVA revealed that there were decreases in RDBM times across age, therefore infants are faster at performing RDBMs over time, regardless of toy type, hand used, or hand preference. The results of the present study suggest that when exploring the development of hand preference, we should consider the influence of age, hand preference, and hand used.

Sitting Capacity and Performance in Infants with Typical Development and Infants with Motor Delay.

AIMS: Infants with neuromotor disorders demonstrate delays in sitting skills (decreased capacity) and are less likely to maintain independent sitting during play than their peers with typical development (decreased performance). This study aimed to quantify developmental trajectories of sitting capacity and sitting performance in infants with typical development and infants with significant motor delay and to assess whether the relationship between capacity and performance differs between the groups. METHODS: Typically developing infants (n = 35) and infants with significant motor delay (n = 31) were assessed longitudinally over a year following early sitting readiness. The Gross Motor Function Measure (GMFM) Sitting Dimension was used to assess sitting capacity, and a 5-min free play observation was used to assess sitting performance. RESULTS: Both capacity and performance increased at a faster rate initially, with more deceleration across time, in infants with typical development compared to infants with motor delay. At lower GMFM scores, changes in GMFM sitting were associated with larger changes in independent sitting for infants with typical development, and the association between GMFM sitting and independent sitting varied more across GMFM scores for typically developing infants. CONCLUSIONS: Intervention and assessment for infants with motor delay should target both sitting capacity and sitting performance.

Early, concurrent, and consistent hand preferences predict stacking in toddlerhood.

Stacking is a hallmark of fine motor skill development and requires skilled hand use. One mechanism for children to gain manual proficiency involves establishing a hand preference that creates practice differences between the hands as the preferred hand is used more often and in different ways than the other. Prior work found that stacking skill emerged earlier for infants with an identifiable hand preference. However, it is not known how hand preference relates to later toddler stacking performance. This study examined the effects of early hand preference (infant pattern), concurrent hand preference (toddler pattern), and consistent hand preference (infant to toddler pattern) on toddler stacking skills. Sixty-one toddlers, whose hand preferences as infants were known, were assessed for their toddler hand preference and their stacking skill across 7 monthly visits from 18 to 24 months of age. Using multilevel Poisson longitudinal analysis, children with hand preferences that were consistent across both infancy and toddlerhood were more successful at stacking, compared to those with inconsistent preferences across the infant and toddler periods. Thus, consistency of hand preferences during the first 2 years likely contributes toward individual differences in the development of fine motor skills.

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.

The Effect of Early-Life Seizures on Cognitive and Motor Development: A Case Series.

PURPOSE: This case series documents developmental changes over time and in response to a novel intervention, Sitting Together and Reaching to Play (START-Play), in children with early-life seizures. METHODS: Thirteen children with early-life seizures were included from a subset of participants in the START-Play multisite, randomized controlled trial. Seven received 3 months of twice weekly START-Play intervention; 6 continued with usual care early intervention. Bayley Scales of Infant Development-III (Cognitive Composite), Gross Motor Function Measure-66 Item Set, Assessment of Problem-Solving in Play, and reaching assessments were administered at baseline, 3, 6, and 12 months postbaseline. Change scores are reported at 3 and 12 months postbaseline. RESULTS: Over time, plateau or decline was noted in standardized cognition measures; motor development improved or was stable. Children receiving START-Play showed positive trends in problem-solving (71.4%) and reaching behaviors (57.2%). CONCLUSIONS: Interventions such as START-Play that combine motor and cognitive constructs may benefit children with early-life seizures.

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.

Infant posture and caregiver-provided cognitive opportunities in typically developing infants and infants with motor delay.

Infants' developing motor skills-including mastery of new postures such as sitting and standing-affect opportunities for learning that facilitate cognitive development. But how infant posture affects caregiver behavior is largely unexplored. Moreover, we know little about effects of posture on learning opportunities in infants with motor delay. This study asked how infants with typical development and infants with significant motor delay use various postures during play, and whether posture is related in real time to caregiver-provided cognitive learning opportunities. Infants were videotaped five times over the course of a year in a free play session with a caregiver, starting when they demonstrated initial sitting skills. Posture and cognitive opportunities were coded moment-by-moment to assess duration and temporal overlap. We found that infants with typical development and infants with motor delay displayed similar use of postures initially, but infants with typical development demonstrated more mature postures over time. We also found that for both groups of infants, caregivers were most likely to provide cognitive opportunities when infants were sitting independently, and least likely when infants were supine. Our findings highlight the importance of upright sitting in typical and atypical infant development and suggest potential areas of intervention for infants with motor delay.

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.

START-Play Physical Therapy Intervention Impacts Motor and Cognitive Outcomes in Infants With Neuromotor Disorders: A Multisite Randomized Clinical Trial.

OBJECTIVE: Our objective was to evaluate the efficacy of the Sitting Together and Reaching to Play (START-Play) intervention in young infants with neuromotor disorders. METHOD: This randomized controlled trial compared usual care early intervention (UC-EI) with START-Play plus UC-EI. Analyses included 112 infants with motor delay (55 UC-EI, 57 START-Play) recruited at 7 to 16 months of age across 5 sites. START-Play included twice-weekly home visits with the infant and caregiver for 12 weeks provided by physical therapists trained in the START-Play intervention; UC-EI was not disrupted. Outcome measures were the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley); the Gross Motor Function Measure; reaching frequency; and the Assessment of Problem Solving in Play (APSP). Comparisons for the full group as well as separate comparisons for infants with mild motor delay and infants with significant motor delay were conducted. Piecewise linear mixed modeling estimated short- and long-term effects. RESULTS: For infants with significant motor delay, positive effects of START-Play were observed at 3 months for Bayley cognition, Bayley fine motor, and APSP and at 12 months for Bayley fine motor and reaching frequency outcomes. For infants with mild motor delay, positive effects of START-Play for the Bayley receptive communication outcome were found. For the UC-EI group, the only difference between groups was a positive effect for the APSP outcome, observed at 3 months. CONCLUSION: START-Play may advance reaching, problem solving, cognitive, and fine motor skills for young infants with significant motor delay over UC-EI in the short term. START-Play in addition to UC-EI may not improve motor/cognitive outcomes for infants with milder motor delays over and above usual care. IMPACT: Concepts of embodied cognition, applied to early intervention in the START-Play intervention, may serve to advance cognition and motor skills in young infants with significant motor delays over usual care early intervention. LAY SUMMARY: If you have a young infant with significant delays in motor skills, your physical therapist can work with you to develop play opportunities to enhance your child's problem solving, such as that used in the START-Play intervention, in addition to usual care to help your child advance cognitive and motor skills.

Preschool language ability is predicted by toddler hand preference trajectories.

Prior work has found links between consistency in toddler handedness for the fine motor skill role-differentiated bimanual manipulation (RDBM), and language development at 2 and 3 years of age. The current study investigated whether consistency in handedness from 18 to 24 months (N = 90) for RDBM predicts receptive and expressive language abilities assessed using the Preschool Language Scales 5th edition (PLS-5) at 5 years old. Latent class growth analyses identified 3 stable RDBM hand preference trajectories: a left hand preference with moderate right hand use (left-moderate right), a right hand preference with moderate left hand use (right-moderate left), and a right hand preference with only mild left hand use (right-mild left). At 5 years of age, children with a right-mild left handedness trajectory as toddlers scored significantly higher on receptive and expressive language abilities compared to children with a left-moderate right hand preference. Children with a right-mild left hand preference for RDBM also scored significantly higher on receptive language abilities compared to children with a right-moderate left RDBM hand preference. Children with left-moderate right and children with a right-moderate left hand preference for RDBM as toddlers did not differ in receptive or expressive language abilities at 5 years. Results indicate that individual differences in hand preference consistency for fine motor skill in toddlerhood have cascading effects on language outcomes into the preschool years. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

A Physical Therapy Intervention to Advance Cognitive and Motor Skills: A Single Subject Study of a Young Child With Cerebral Palsy.

BACKGROUND: Physical therapy interventions for children with severe motor impairments do not address the relationship between motor and cognitive development. PURPOSE: Evaluate the potential of a physical therapy intervention focusing on enhancing cognitive and motor outcomes in a child with severe motor impairments. DESIGN: AB phase design without reversal. METHODS: One child participated in 8 assessments from 4 to 29 months of age. The START-Play intervention was provided for 3 months following 4 baseline assessments over 12 months. Total Gross Motor Function Measure (GMFM), Sitting, Reaching, and Problem Solving assessments were completed. Visual inspection, 2 standard deviation (SD) Band Method, and percent of nonoverlapping data methods evaluated change. RESULTS: This child had improved GMFM total and sitting scores, increased frequency of toys contacts, and increased rate of problem-solving behaviors following intervention. CONCLUSION: START-Play shows promise for children with severe motor impairments. Additional research is needed to evaluate efficacy.

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

The development of sitting changes how much infants are able to explore objects. Infants who can sit with their arms free are likely to explore their environment more effectively than prop sitters, as their hands are free to explore. We sought to quantify how prop sitters differed in the amount of visual and manual exploration of objects from arms-free sitters. Infants younger than 7 months (n = 31) were recruited at sitting emergence, either prop or arms-free sitting without the ability to change positions. Infants were grouped into sitting stages at baseline: prop (n = 17) or wobbly/arms-free (n = 14). Across three visits (baseline, 3 weeks later, 6-8 weeks later), researchers assessed the infants' total gross motor skill, sitting skill, and object looking and active exploration. Infants' gross motor and sitting skill was assessed using the Gross Motor Function Measure (GMFM)-66 total scores and GMFM-88 sitting dimension scores. While researchers supported infants in sitting, object looking and exploration were assessed using a series of three object exploration tasks and scoring modified slightly from the Early Problem Solving Indicator at each visit. Differences between trajectories of prop and wobbly/arms-free sitters for the frequencies of two behaviors, looks and explores, were analyzed using longitudinal multilevel modeling. Prop sitters initially explored toys less frequently, but increased their exploration more quickly, than wobbly/arms-free sitters. Sitting skill predicted minor changes in the development of looking; both stage and skill predicted changes uniquely in the development of exploration. These findings suggest that independent, arms-free sitting changes how capable infants are of exploring objects visually and manually.

Assessment of Parent-Child Interaction Is Important With Infants in Rehabilitation and Can Use High-Tech or Low-Tech Methods.

Parents are their infant's first teachers and play a very important role in early development. Early intervention strives to enhance infant participation in the family, and regulations require the engagement of families in assessment and intervention. Infants born preterm or with motor impairments demonstrate altered social engagements that can influence parent-child interaction and the efficacy of therapy services. However, in research focused on the efficacy of interventions or in clinical practice, therapists rarely assess or report on the quality of parent-infant interaction. Understanding these interactions can help determine what perceptual motor opportunities parents provide that can enhance learning. This Perspective article will: (1) present evidence on the need for early assessment and ongoing measurement of parent-infant interaction; (2) describe an example of each of 3 methods for assessment of parent-child interaction-low-tech, low-resource (Dyadic Mutuality Code), low-tech, high-resource (Parent Children Early Relational Assessment), and high-tech, high-resource (customized behavioral coding); (3) compare 3 approaches theoretically highlighting the strengths and weaknesses of each assessment; and (4) reflect on the challenges and value of adding these measures to future research on the efficacy of interventions and clinical practice.

The Development of Object Construction from Infancy through Toddlerhood.

Early in development, children explore and combine objects in increasingly complex ways. One manual skill, object construction, represents a major shift in how objects are explored relative to other objects. Despite recent connections with cognitive functioning such as spatial skills, the development of object construction ability has rarely been studied and its trajectory has not been adequately described. The purpose of this study was to describe the development of three types of object construction (stacking, nesting, affixing) across 5 monthly infant visits and 7 monthly toddler visits using a longitudinal design and a large sample size. Infants (10-14 months, n=131) and toddlers drawn from the infant sample (18-24 months, n=65) were given sets of age-appropriate toys each of which elicited at least one type of constructive play. We described success at different construction tasks and identified trends for construction skill for infant and toddler development using multilevel modeling. We found that each of the three construction actions developed in unique ways across the 10-24-month period. Infant construction skill predicted the development of toddler skill, but toddler construction skill diverged from infant trajectories. We discuss the role of combination strategies in the development of object construction skill and how object construction could be related to other domains of development.

Evolution and development of handedness: An Evo-Devo approach.

Hand preference is a sensorimotor skill whose development both reflects and promotes the development of hemispheric lateralization for manual and cognitive functions. Extensive comparative, crosscultural, and paleoanthropological evidence demonstrates the prevalence of limb lateralized preferences across vertebrate species and the prevalence of right-handedness within hominid evolution. Many reviews of the evolution and development of human handedness have proposed adaptive explanations for its evolution. However, during the last 3 decades a new approach to understanding evolution (the Extended Evolutionary Synthesis-EES) provided a persuasive alternative to the conventional (Neo-Darwinian Synthetic Theory-ST) evolutionary and developmental accounts. EES combines modern evolutionary and developmental research (Evo-Devo) in ways that alter understanding of natural selection, adaptation, and the role of genes in development and evolution. These changes make obsolete all past accounts of the evolution and development of lateralization and handedness because EES/Evo-Devo requires new study designs. The developmental trajectories of any structural or functional trait must be specified so that it may be related to variations in the developmental trajectories of other traits. First, we describe how the EES/Evo-Devo differs from the conventional ST, particularly for understanding of how traits develop. Then, we apply Evo-Devo to the study of handedness development in infancy and its relation to the development of other cognitive functions. Finally, we argue that identifying the development of atypical traits would benefit from knowledge of the range of individual differences in typical developmental trajectories of hand-use preference and their relation to variations in the developmental trajectories of cognitive functions.

Sitting Together And Reaching To Play (START-Play): Protocol for a Multisite Randomized Controlled Efficacy Trial on Intervention for Infants With Neuromotor Disorders.

Background: There is limited research examining the efficacy of early physical therapy on infants with neuromotor dysfunction. In addition, most early motor interventions have not been directly linked to learning, despite the clear association between motor activity and cognition during infancy. Objective: The aim of this project is to evaluate the efficacy of Sitting Together And Reaching To Play (START-Play), an intervention designed to target sitting, reaching, and motor-based problem solving to advance global development in infants with motor delays or neuromotor dysfunction. Design: This study is a longitudinal multisite randomized controlled trial. Infants in the START-Play group are compared to infants receiving usual care in early intervention (EI). Setting: The research takes place in homes in Pennsylvania, Delaware, Washington, and Virginia. Participants: There will be 140 infants with neuromotor dysfunction participating, beginning between 7 to 16 months of age. Infants will have motor delays and emerging sitting skill. Intervention: START-Play provides individualized twice-weekly home intervention for 12 weeks with families to enhance cognition through sitting, reaching, and problem-solving activities for infants. Ten interventionists provide the intervention, with each child assigned 1 therapist. Measurements: The primary outcome measure is the Bayley III Scales of Infant Development. Secondary measures include change in the Early Problem Solving Indicator, change in the Gross Motor Function Measure, and change in the type and duration of toy contacts during reaching. Additional measures include sitting posture control and parent-child interaction. Limitations: Limitations include variability in usual EI care and the lack of blinding for interventionists and families. Conclusions: This study describes usual care in EI across 4 US regions and compares outcomes of the START-Play intervention to usual care.

Supporting play exploration and early developmental intervention versus usual care to enhance development outcomes during the transition from the neonatal intensive care unit to home: a pilot randomized controlled trial.

BACKGROUND: While therapy services may start in the Neonatal Intensive Care Unit (NICU) there is often a gap in therapy after discharge. Supporting Play Exploration and Early Development Intervention (SPEEDI) supports parents, helping them build capacity to provide developmentally supportive opportunities starting in the NICU and continuing at home. The purpose of this single blinded randomized pilot clinical trial was to evaluate the initial efficacy of SPEEDI to improve early reaching and exploratory problem solving behaviors. METHODS: Fourteen infants born very preterm or with neonatal brain injury were randomly assigned to SPEEDI or Usual Care. The SPEEDI group participated in 5 collaborative parent, therapist, and infant interventions sessions in the NICU (Phase 1) and 5 at home (Phase 2). Parents provided daily opportunities designed to support the infants emerging motor control and exploratory behaviors. Primary outcome measures were assessed at the end of the intervention, 1 and 3 months after the intervention ended. Reaching was assessed with the infant supported in an infant chair using four 30 s trials. The Early Problem Solving Indicator was used to evaluate the frequency of behaviors during standardized play based assessment. Effect sizes are including for secondary outcomes including the Test of Infant Motor Performance and Bayley Scales of Infant and Toddler Development. RESULTS: No group differences were found in the duration of toy contact. There was a significant group effect on (F1,8 = 4.04, p = 0.08) early exploratory problem-solving behaviors with infants in the SPEEDI group demonstrating greater exploration with effect sizes of 1.3, 0.6, and 0.9 at the end of the intervention, 1 and 3 months post-intervention. CONCLUSIONS: While further research is needed, this initial efficacy study showed promising results for the ability of SPEEDI to impact early problem solving behaviors at the end of intervention and at least 3 months after the intervention is over. While reaching did not show group differences, a ceiling effect may have contributed to this finding. This single blinded pilot RCT was registered prior to subject enrollment on 5/27/14 at ClinicalTrials.Gov with number NCT02153736.

The development of neuromotor skills and hand preference during infancy.

Assessing infant handedness has been controversial. Different assessment techniques and theoretical approaches produce different results. Evidence from a dynamic systems perspective showed that the development of postural control during infancy affects the expression of an infant's handedness. However, others found that developmental changes in postural control influenced the amount of symmetrical (bimanual) reaching during infancy, but not hand preference. Since most studies of infant handedness use age to assess development, perhaps measures of an infant's developing neuromotor control, irrespective of age, would better predict changes in an infant's hand preference. To assess neuromotor development, items from [Touwen's (1976) Neurological development in infancy. Lavenham, Suffolk: The Lavenham Press, LTD]. "Group III" indices were used. These items assess developmental changes in neuromotor abilities throughout the 6-14-month age period. Hand preference for acquiring objects was measured during these same months. Group Based Trajectory Models (GBTM) of 380 infants identified four different groups of infants according to the trajectory of the development of their hand preferences (32% Early Right, 12% Early Left, 25% Late Right, 30% No Preference). A multilevel model was used to compare these four developmental trajectories according to age and neuromotor development. Age, not neuromotor development, is a better predictor of differences in developmental trajectories of the four hand preference groups. However, Late Right infants are significantly less developed at 6 months than No Preference, Early Right and Left infants and both Early Right and Left infants are most advanced at 6 months. All groups exhibit similar rates of neuromotor development indicating no "catch-up" by the Late Right infants. Thus, any assessment of infant handedness will incorporate necessarily four groups of infants with differently developing hand preferences and neuromotor abilities.

Toddler hand preference trajectories predict 3-year language outcome.

A growing body of work suggests that early motor experience affects development in unexpected domains. In the current study, children's hand preference for role-differentiated bimanual manipulation (RDBM) was measured at monthly intervals from 18 to 24 months of age (N = 90). At 3 years of age, children's language ability was assessed using the Preschool Language Scales 5th edition (PLS™-5). Three distinct RDBM hand preference trajectories were identified using latent class growth analysis: (1) children with a left hand preference but a moderate amount of right hand use; (2) children with a right hand preference but a moderate amount of left hand use; and (3) children with a right hand preference and only a mild amount of left hand use. Stability over time within all three trajectories indicated that children did not change hand use patterns from 18 to 24 months. Children with the greatest amount of preferred (i.e., right) hand use demonstrated higher expressive language scores compared to children in both trajectories with moderate levels of non-preferred hand use. Children with the greatest amount of right hand use also had higher scores for receptive language compared to children with a right hand preference but moderate left hand use. Results support that consistency in handedness as measured by the amount of preferred hand use is related to distal language outcomes in development.

Do hand preferences predict stacking skill during infancy?

The cascade theory of handedness suggests that hand preferences develop from a history of cascading and sequentially developing manual asymmetries for a variety of actions. Infants who consistently use their preferred hand for a variety of actions likely would gain proficiency using that preferred hand and, consequently, perform more proficiently on other challenging manual tasks. One such task is object stacking, which has been linked with a number of cognitive abilities. If infant hand preference facilitates the development of stacking skill, then this could provide a link by which early hand preference might affect the development of cognition. From a sample of 380 infants assessed for an acquisition hand preference across 6-14 months, 131 infants were assessed for stacking skill from 10 to 14 months at monthly visits. Four unique handedness sub-groups were identified from the 380-infant sample: left, trending right, stable right, or no hand preference. Each of the four hand preference groups exhibited different trajectories in the development of their stacking skills. Left- and stable right-handers stacked more items than infants with no preference by 14 months, whereas infants with a trending right preference did not. The proportion of preferred hand use (right and left) from 6 to 9 months also predicted an earlier initial onset of stacking skill, whereas the proportion of only right hand use did not. Thus, the development of a hand preference predicts an earlier emergence of stacking skill and may have implications for other domains of infant cognitive development.