Toddler hand preference trajectories predict 3-year language outcome

Hand preference trajectories as predictors of language outcomes above and beyond SES: Infant patterns explain more variance than toddler patterns at 5 years of age

Prior studies found hand preference trajectories predict preschool language outcomes. However, this approach has been limited to examining bimanual manipulation in toddlers. It is not known whether hand preference during infancy for acquiring objects (i.e., reach-to-grasp) similarly predicts childhood language ability. The current study explored this motor-language developmental cascade in 90 children. Hand preference for acquiring objects was assessed monthly from 6 to 14 months and language skill was assessed at 5 years. Latent class growth analysis identified three infant hand preference classes: left, early right, and late right. Infant hand preference classes predicted 5-year language skills. Children in the left and early right classes, who were categorized as having a consistent hand preference, had higher expressive and receptive language scores relative to children in the inconsistent late right class. Consistent classes did not differ from each other on language outcomes. Infant hand preference patterns explained more variance for expressive and receptive language relative to previously reported toddler hand preference patterns, above and beyond socioeconomic status (SES). Results suggest that hand preference, measured at different time points across development using a trajectory approach, is reliably linked to later language.

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.

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.

How babies use their hands to learn about objects: Exploration, reach-to-grasp, manipulation, and tool use

Object play is essential for infant learning, and infants spend most of their day with objects. Young infants learn about objects and their properties through multimodal exploration facilitated by caregivers. They figure out how to transport their hands to where objects are, and how to grasp objects in increasingly complex ways. Building on earlier experiences, they learn how to use their hands collaboratively to act on objects, and how to use objects to act on other objects in instrumental ways. These changes in how infants use their hands occur during the most rapid period of motor development and may have important downstream implications for other domains. Recent research findings have established the importance of effective fine motor skills for later academic skills, yet our understanding of the factors that influence the early development of hand skills is sparse at best. Latest research on reaching, grasping, object manipulation, hands collaboration, and tool use is reviewed and connections among these developments are explained from the perspective of developmental cascades. This article is categorized under: Psychology > Motor Skill and Performance Psychology > Development and Aging.

Developmental models of motor-evoked potential features by transcranial magnetic stimulation across age groups from childhood to adulthood

To derive the maturation of neurophysiological processes from childhood to adulthood reflected by the change of motor-evoked potential (MEP) features. 38 participants were recruited from four groups (age mean in years [SD in months], number (males)): children (7.3 [4.2], 7(4)), preadolescents (10.3 [6.9], 10(5)), adolescents (15.3 [9.8], 11(5)), and adults (26.9 [46.2], 10(5)). The navigated transcranial magnetic stimulation was performed on both hemispheres at seven stimulation intensity (SI) levels from sub- to supra-threshold and targeted to the representative cortical area of abductor pollicis brevis muscle. MEPs were measured from three hand- and two forearm-muscles. The input-output (I/O) curves of MEP features across age groups were constructed using linear mixed-effect models. Age and SI significantly affected MEP features, whereas the stimulated side had a minor impact. MEP size and duration increased from childhood to adulthood. MEP onset- and peak-latency dropped in adolescence, particularly in hand muscles. Children had the smallest MEPs with the highest polyphasia, whereas I/O curves were similar among preadolescents, adolescents, and adults. This study illustrates some of the changing patterns of MEP features across the ages, suggesting developing patterns of neurophysiological processes activated by TMS, and to motivate studies with larger sample size.

From Hemispheric Asymmetry through Sensorimotor Experiences to Cognitive Outcomes in Children with Cerebral Palsy

Recent neuroimaging studies allowed us to explore abnormal brain structures and interhemispheric connectivity in children with cerebral palsy (CP). Behavioral researchers have long reported that children with CP exhibit suboptimal performance in different cognitive domains (e.g., receptive and expressive language skills, reading, mental imagery, spatial processing, subitizing, math, and executive functions). However, there has been very limited cross-domain research involving these two areas of scientific inquiry. To stimulate such research, this perspective paper proposes some possible neurological mechanisms involved in the cognitive delays and impairments in children with CP. Additionally, the paper examines the ways motor and sensorimotor experience during the development of these neural substrates could enable more optimal development for children with CP. Understanding these developmental mechanisms could guide more effective interventions to promote the development of both sensorimotor and cognitive skills in children with CP.

Growing into your hand: the developmental trajectory of the body model

We rely on accurate body representations to successfully interact with the environment. As adults, we rely on many years of experience with a body that has stayed relatively the same size. Children, however, go through periods of rapid growth and whether or not their body representation matches this physical growth is unknown. To address this question, we examined the developmental trajectory of the body model of the hand. The body model is the representation of our bodies that underlies position sense. We recruited a group of children (8-16 years) and a control group of young adults (18-26 years) and asked them to complete the body model task. In this task, participants estimated the location of ten different landmarks (the tips and metacarpophalangeal joints of each of their five fingers). The position (XY location) of each estimate was tracked using an Optotrak camera. From the XY locations we derived hand width and finger length. Not surprisingly, children's physical hand width and finger length were smaller than adults but remarkably, the body model, was similar for both groups. This result indicates that children overestimate hand size and suggests that the body model is ahead of physical growth. This result contradicts the notion that body representation lags physical growth during puberty, accounting for the clumsy motor behaviour characteristic of teens. We discuss the results in relation to the different taxonomies of body representation and how an enlarged representation of the hand during childhood may influence action.

Handedness Development: A Model for Investigating the Development of Hemispheric Specialization and Interhemispheric Coordination

The author presents his perspective on the character of science, development, and handedness and relates these to his investigations of the early development of handedness. After presenting some ideas on what hemispheric specialization of function might mean for neural processing and how handedness should be assessed, the neuroscience of control of the arms/hands and interhemispheric communication and coordination are examined for how developmental processes can affect these mechanisms. The author’s work on the development of early handedness is reviewed and placed within a context of cascading events in which different forms of handedness emerge from earlier forms but not in a deterministic manner. This approach supports a continuous rather than categorical distribution of handedness and accounts for the predominance of right-handedness while maintaining a minority of left-handedness. Finally, the relation of the development of handedness to the development of several language and cognitive skills is examined.

Which hand knows the "right" word? What hand selection reveals about vocabulary in pre-and school-aged children

Research has shown that infants with increased right-hand selection for their first gestures perform better at an array of language tasks when they are tested later as toddlers. There is a smaller body of literature which focuses on preschoolers and how their right-handed movements relate to their speech and vocabulary development. Some research has established a connection between right-hand preference for grasping and speech production ability in preschool children, but the link to gestures is relatively unexplored in this age group. We investigated if lateralized gestures (pointing) are related to measures of language development (vocabulary) in a preschool-age sample. Specifically, typically developing children (aged 3-6) completed the Peabody Picture Vocabulary Test (PPVT) to assess receptive language. We recorded their hand preference for pointing during the PPVT and the incidence of mistakes (pointing to the wrong picture). Despite the length of the test, children were more likely to select a correct response with their right hand. This result suggests a relationship between lateralized communicative gestures (pointing) and receptive language. This study provides evidence for an intimate relationship between right-handed manual movement and language development. Implications of this finding include developing simple fine-motor tasks to detect and/or ameliorate delayed language development.

Motor functioning in developmental psychopathology: A review of autism as an example context

BACKGROUND

Motor development research has seen substantial recent growth. However, much remains to be understood about the nature and extent of motor impairments in neurodevelopmental disorders, including their potential as early markers and/or causal determinants of downstream functioning in other domains.

AIMS AND METHODS

In this narrative review, drawing primarily on the autism literature by way of example, we review current accounts of the nature and consequences of motor functioning. We consider conventional approaches to measurement and study design, and current limited approaches to tackling heterogeneity.

CONCLUSIONS AND IMPLICATIONS

We argue that ongoing adherence to traditional diagnostic outcome classification stands in the face of mounting evidence that characteristics of neurodevelopmental disorders lie on a continuum with variability in the general population, and that three broad research avenues stand to offer a better understanding of motor functioning: The use of technology and advanced statistical methods for a more nuanced understanding of motor abilities; exploiting the prospective longitudinal tracking of at-risk infants to understand developmental consequences of early motor difference; and employing randomized controlled trials to test the utility of motor therapies whilst also testing causal hypotheses about the role of motor functioning.

Early Lateralization of Gestures in Autism: Right-Handed Points Predict Expressive Language

Children with autism spectrum disorder (ASD) produce fewer deictic gestures, accompanied by delays/deviations in speech development, compared to typically-developing (TD) children. We ask whether children with ASD-like TD children-show right-hand preference in gesturing and whether right-handed gestures predict their vocabulary size in speech. Our analysis of handedness in gesturing in children with ASD (n = 23, M_age = 30-months) and with TD (n = 23, M_age = 18-months) during mother-child play showed a right-hand preference for TD children-but not for children with ASD. Nonetheless, right-handed deictic gestures predicted expressive vocabulary 1 year later in both children with ASD and with TD. Handedness for gesture, both hand preference and amount of right-handed pointing, may be an important indicator of language development in autism and typical development.

Gaze behaviour to lateral face stimuli in infants who do and do not gain an ASD diagnosis

Cerebral lateralisation of function is common characteristic across vertebrate species and is positively associated with fitness of the organism, in humans we hypothesise that it is associated with cognitive fitness. This investigation evaluated the early development of lateralised gaze behaviour for face stimuli in infants at high and low risk for autism from the British Autism Sibling Infant Study (BASIS). The BASIS cohort includes a low risk group and three high-risk groups who at age 3 were developing (i) typically, (ii) atypically or (iii) had received a diagnosis for ASD. Using eye-tracking data derived from a face pop-out task at 6 and 14 months of age, all non-ASD groups showed a bias for stimuli on the left at both timepoints. At 6 months the ASD group demonstrated a preference for stimuli on the right and were slower than their neurotypical counterparts to look at faces on the left. However, by 14 months these differences disappear. Longitudinal associations between lateral looking behaviour at 6 months and language and motor ability at 14 months were also found. Results suggest that infants who go on to be diagnosed with autism exhibit early differences in gaze behaviour that may be associated with subsequent cognitive outcomes.

A perspective on the development of hemispheric specialization, infant handedness, and cerebral palsy

Cerebral Palsy (CP), a common form of neurological pediatric disability, results from pre- or perinatal brain injury. Although there is growing evidence of the efficacy of motor learning-based therapies, several factors interact to produce variability in impairment and limit the effectiveness of these therapies. The variability of hand function present in children with CP indicates that a range of developmental pathways must contribute to the manifestation of individually unique characteristics of impairment. Despite two decades of progress using therapies derived from understanding the mechanisms controlling hand function, very little is known about the sensorimotor experiences occurring during development that likely shape later functional problems for children with CP. In this "perspective" paper, we propose that the study of the development of motor skills in typically developing infants may reveal experiential factors potentially important for creating remedial therapies for children with CP. Specifically, we use the development of infant handedness, a model of hemispheric specialization of function, as an example of how self-generated experiences and sensorimotor feedback can shape the development of limb control and hemispheric specialization. We illustrate how early sensorimotor asymmetries concatenate into pronounced differences in skill between the two hands. We suggest that this model of infant handedness provides a framework for studying the individual differences manifested in children with CP. These differences likely arise from aberrant sensorimotor experiences created by sensorimotor circuits disrupted by the early brain injury. We conclude that knowledge of the developmental events, including subtle motor behaviors, that shape sensorimotor pathways, can improve treatment options for children with CP.

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).

Identifying typical trajectories in longitudinal data: modelling strategies and interpretations

Individual-level longitudinal data on biological, behavioural, and social dimensions are becoming increasingly available. Typically, these data are analysed using mixed effects models, with the result summarised in terms of an average trajectory plus measures of the individual variations around this average. However, public health investigations would benefit from finer modelling of these individual variations which identify not just one average trajectory, but several typical trajectories. If evidence of heterogeneity in the development of these variables is found, the role played by temporally preceding (explanatory) variables as well as the potential impact of differential trajectories may have on later outcomes is often of interest. A wide choice of methods for uncovering typical trajectories and relating them to precursors and later outcomes exists. However, despite their increasing use, no practical overview of these methods targeted at epidemiological applications exists. Hence we provide: (a) a review of the three most commonly used methods for the identification of latent trajectories (growth mixture models, latent class growth analysis, and longitudinal latent class analysis); and (b) recommendations for the identification and interpretation of these trajectories and of their relationship with other variables. For illustration, we use longitudinal data on childhood body mass index and parental reports of fussy eating, collected in the Avon Longitudinal Study of Parents and Children.

Do Gross and Fine Motor Skills Differentially Contribute to Language Outcomes? A Systematic Review

Background: Changes in motor development provide children with new learning opportunities to interact with objects, their environment, and with caregivers. Previous research finds that both gross and fine motor skills are predictive of later language outcomes across early infancy and childhood. However, gross and fine motor skills afford different types of interactions. Thus, gross and fine motor skills may potentially differ in the developmental trajectories through which cascading changes in language may occur. The aim of the present study was to investigate whether there are differences in the predictive capacities of gross and fine motor skills toward language outcomes across infancy and early childhood in typical development. Method: A systematic review of existing literature on motor-language cascades was conducted in across studies measuring gross and/or fine motor and language development in children from 0 to 5 years old. Searches were conducted in PsycINFO, PubMed, and MEDLINE. Keywords used were a combination of "gross motor," "fine motor," "motor performance," "motor development," or "psychomotor development" along with "language," "language development," or "communication skills." Two independent reviewers screened abstracts and full texts based on inclusion and exclusion criteria. Results: A total of 23 articles were retained. Of these, seven studies measured only gross motor skills, four studies measured only fine motor skills, and 12 studies measured both gross and fine motor skills in the same study. Studies used a variety of measures to assess gross motor skills, fine motor skills, and language development (e.g., parent report, in lab observations, standardized assessment), and findings varied based on analyses used. Results demonstrated that both gross and fine motor skills are related to language outcomes, but due to a smaller amount of studies testing fine motor skills, conclusions regarding whether one is more important for language outcomes cannot be drawn. Conclusions: We conclude that both gross and fine motor skills help foster language development from infancy to early childhood. Limitations regarding current knowledge regarding the mechanisms that underlie motor-language cascades are discussed, as well as the need for more studies on fine motor skills.

Factor analysis of the Home Handedness Questionnaire: Unimanual and role differentiated bimanual manipulation as separate dimensions of handedness

Questionnaires are commonly used to measure handedness. However, popular measures do not capture hand preference by skill type, thus reducing handedness to a single dimension. An exception is the Home Handedness Questionnaire (HHQ), an action-based measure developed initially for children, which measures skills across two dimensions of handedness: unimanual actions and role differentiated bimanual manipulation (RDBM). The goal of the current study was to confirm the factor structure of the HHQ in a large sample of adults (N = 1051). A secondary goal was to measure RDBM hand preference in adults. To further validate the HHQ, participants also completed the Edinburgh Handedness Inventory (EHI). Confirmatory factor analysis verified the two-factor structure of the HHQ, and a one-factor solution was replicated for the EHI. Individuals that were classified as consistent on the EHI had stronger preferences for unimanual and RDBM hand use on the HHQ. Right hand patterning was reduced for RDBM compared to unimanual on the HHQ, and the EHI. The HHQ was found to be reliable and valid against the EHI. The HHQ offers researchers a tool to examine individual differences across manual skills that comprise the neuropsychological phenomenon handedness, and to more broadly examine laterality patterns with respect to cognition.

The home handedness questionnaire: pilot data from preschoolers

While handedness questionnaires are widely used in adults, there is no comparable measure designed specifically for children. The current study developed the Home Handedness Questionnaire (HHQ), a new measure for preschoolers administered by parents using common household items. The HHQ has two scales that distinguish action types typically combined on other measures: actions performed with only the right or left hand (i.e., unimanual, such as holding a toothbrush), and actions performed with one hand holding the object for the other hand's action (i.e., role-differentiated bimanual manipulation or RDBM, such as unscrewing a lid from a jar). The HHQ was able to detect right preference, left preference, and no preference for unimanual and RDBM actions in a proof of concept study in 3-year-olds (N = 64). The HHQ identified a majority of children as right-handed, but was also sensitive to variability in direction across skill types. Approximately one-quarter of children in the sample had mixed preferences for the two types of manual skills, suggesting that for a subgroup of children, hand use patterns may still be undergoing change. Suggestions for refining the HHQ are discussed. Overall, the HHQ is a promising multidimensional parent-led tool for assessing preschool handedness.

Sensorimotor lateralization scaffolds cognitive specialization

In this chapter, we review hemispheric differences for sensorimotor function and cognitive abilities. Specifically, we examine the left-hemisphere specialization for visuomotor control and its interplay with language, executive function, and musical training. Similarly, we discuss right-hemisphere lateralization for haptic processing and its relationship to spatial and numerical processing. We propose that cerebral lateralization for sensorimotor functions served as a foundation for the development of higher cognitive abilities and their hemispheric functional specialization. We further suggest that sensorimotor and cognitive functions are inextricably linked. Based on the studies discussed in this chapter our view is that sensorimotor control serves as a loom upon which the fibers of language, executive function, spatial, and numerical processing are woven together to create the fabric of cognition.

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.

How Might the Relation of the Development of Hand Preferences to the Development of Cognitive Functions be Examined During Infancy: A Sketch?

Investigations of the relation of the development of hand preferences to the development of other sensorimotor and cognitive abilities are plagued by confusing and contradictory results. In part, the confusion derives from the failure to create accurate, appropriate, and reliable descriptions of the development of hand preferences and the cognitive or sensorimotor ability of interest. This paper sketches an ideal longitudinal study (from birth through 5 years) with a large sample size that should provide reliable evidence for the understanding of the relation of hand preferences to cognitive development. Since hand preference differences would affect the way infants engage in manual actions with objects and these differences would likely affect how they come to comprehend object relations, differences in the development of cognition across handedness groups would be a good test of certain forms of embodiment theory.