Fitting handled objects into apertures by 17- to 36-month-old children: The dynamics of spatial coordination

Children plan manual actions similarly in structured tasks and in free play

Visually guided planning is fundamental for manual actions on objects. Multi-step planning-when only the requirements for the initial action are directly visible in the scene-necessitates initial visual guidance to optimize the subsequent actions. We found that 3- to 5-year-old children (n = 23) who exhibited visually guided, multi-step planning in a structured tool-use task (hammering down a peg) also demonstrated visually guided planning during unstructured free play while interlocking Duplo bricks and Squigz pieces. Children who exhibited visually guided planning in the hammering task also spent more time looking at the to-be-grasped free-play object and at their construction during reach and transport compared with children who did not demonstrate multi-step planning in the hammering task. Moreover, visually guided planning in the Duplo and Squigz tasks was positively correlated, indicating that planning generalizes across contexts. Findings show that visually guided planning in young children generalizes across different manual actions on objects, including structured tool use and unstructured free play.

The Motor Melody in action Planning: The Case of Autistic Children and their Non-Autistic Siblings

Objective

it is well known that during an intentional behavior, the final goal of the action shapes the entire sequence of motor acts. This chained organization has been previously demonstrated to be altered in school-age autistic children, who modulate only the final motor act according to the action goal. Here, we investigate the temporal modulation during the intentional action in three groups of preschoolers: neurotypical, autistic, and non-autistic siblings of autistic children.

Method

the participants engaged in a simple task of reaching and grasping an object and placing it into two containers of different sizes.

Results

neurotypical children adjusted both reaching and placing times according to the width of the containers, indicating an action-chained organization. In contrast, both autistic children and non-autistic siblings adapted only the placing - but not the reaching- time according to the container size, exhibiting an unchained organization of intentional actions.

Conclusions

despite not being included among the diagnostic criteria, motor alterations are present in a large number of autistic individuals, detectable from an early age. Being motor signs also expressed by non-autistic siblings, our findings suggest a potential link between motor abnormalities and the pathogenesis of autism. Thereby, tasks similar to the one employed here could be valuable for screening children with an increased likelihood of atypical neurodevelopment.

Look before you reach: Fixation-reach latencies predict reaching kinematics in toddlers

Research on infant and toddler reaching has shown evidence for motor planning after the initiation of the reaching action. However, the reach action sequence does not begin after the initiation of a reach but rather includes the initial visual fixations onto the target object occurring before the reach. We developed a paradigm that synchronizes head-mounted eye-tracking and motion capture to determine whether the latency between the first visual fixation on a target object and the first reaching movement toward the object predicts subsequent reaching behavior in toddlers. In a corpus of over one hundred reach sequences produced by 17 toddlers, we found that longer fixation-reach latencies during the pre-reach phase predicted slower reaches. If the slowness of an executed reach indicates reach difficulty, then the duration of pre-reach planning would be correlated with reach difficulty. However, no relation was found with pre-reach planning duration when reach difficulty was measured by usual factors and independent of reach duration. The findings raise important questions about the measurement of reach difficulty, models of motor control, and possible developmental changes in the relations between pre-planning and continuously unfolding motor plans throughout an action sequence.

The process of learning the designed actions of toys

Many everyday objects require "hidden" affordances to use as designed (e.g., twist open a water bottle). Previous work found a reliable developmental progression in children's learning of designed actions with adult objects such as containers and zippers-from non-designed exploratory actions, to the basics of the designed action, to successful implementation. Many objects designed for children (e.g., toys) also entail designed actions (e.g., interlocking bricks) but might not require a protracted period of discovery and implementation. We encouraged 12- to 60-month-old children (n = 91) and a comparative sample of 20 adults to play with six Duplo bricks to test whether the developmental progression identified for children's learning of adult objects with hidden affordances holds for a popular toy expressly designed for children. We also examined whether children's moment-to-moment behaviors with Duplo bricks inform on general processes involved in discovery and implementation of hidden affordances. With age, children progressed from non-designed exploratory actions, to attempts to interlock, to success, suggesting that the three-step developmental progression revealed with everyday adult objects broadly applies to learning hidden affordances regardless of object type. Detailing the process of learning (the type and timing of children's non-designed actions and attempts to interlock) revealed that the degree of lag between steps of the progression depends on the transparency of the required actions, the availability of perceptual feedback, and the difficulty of the perceptual-motor requirements. Findings provide insights into factors that help or hinder learning of hidden affordances.

Young Children's Interactions with Objects: Play as Practice and Practice as Play

Objects permeate human culture and saturate the imagination. This duality offers both opportunity and challenge. Here we ask how young human children learn to exploit the immense potential afforded by objects that can exist simultaneously in both physical and imaginary realms. To this end, we advance a new framework that integrates the presently siloed literatures on manual skill and play development. We argue that developments in children's real and imagined use of objects are embodied, reciprocal and intertwined. Advances in one plane of action influence and scaffold advances in the other. Consistent with this unified framework, we show how real and imagined interactions with objects are characterized by developmental parallels in how children a) gradually move beyond objects' designed functions, b) extend beyond the self, and c) transcend the present to encompass future points in time and space. As well, we highlight how children's real and imagined interactions with objects are intertwined and reciprocally influence each other throughout development: Play engenders practice and skill in using objects, but just the same, practice using objects engenders advances in play. We close by highlighting the theoretical, empirical and translational implications of this embodied and integrated account of manual skill and play development.

Motor planning and movement execution during goal-directed sequential manual movements in 6-year-old children with autism spectrum disorder: A kinematic analysis

BACKGROUND

Atypical motor functioning is prevalent in children with autism spectrum disorder (ASD). Knowledge of the underlying kinematic properties of these problems is sparse.

AIMS

To investigate characteristics of manual motor planning and performance difficulties/diversity in children with ASD by detailed kinematic measurements. Further, associations between movement parameters and cognitive functions were explored.

METHODS AND PROCEDURES

Six-year-old children with ASD (N = 12) and typically developing (TD) peers (N = 12) performed a sequential manual task comprising grasping and fitting a semi-circular peg into a goal-slot. The goal-slot orientation was manipulated to impose different motor planning constraints. Movements were recorded by an optoelectronic system.

OUTCOMES AND RESULTS

The ASD-group displayed less efficient motor planning than the TD-group, evident in the reach-to-grasp and transport kinematics and less proactive adjustments of the peg to the goal-slot orientations. The intra-individual variation of movement kinematics was higher in the ASD-group compared to the TD-group. Further, in the ASD-group, movement performance associated negatively with cognitive functions.

CONCLUSIONS AND IMPLICATIONS

Planning and execution of sequential manual movements proved challenging for children with ASD, likely contributing to problems in everyday actions. Detailed kinematic investigations contribute to the generation of specific knowledge about the nature of atypical motor performance/diversity in ASD. This is of potential clinical relevance.

Children's use of everyday artifacts: Learning the hidden affordance of zipping

The everyday world is populated with artifacts that require specific motor actions to use objects as their designers intended. But researchers know little about how children learn to use everyday artifacts. We encouraged forty-four 12- to 60-month-old children to unzip a vinyl pouch during a single 60-s trial. Although unzipping a pouch may seem simple, it is not. Unzipping requires precise role-differentiated bimanual actions-one hand must stabilize the pouch while the other hand applies a pulling force on the tab. Moreover, kinematic data from six adults showed that the tolerance limits for applying the forces are relatively narrow (pulling the tab within 63° of the zipper teeth while stabilizing the pouch within 4 cm of the slider). Children showed an age-related progression for the unzipping action. The youngest children did not display the designed pulling action; children at intermediate ages pulled the tab but applied forces outside the tolerance limits (pulled in the wrong direction, failed to stabilize the pouch in the correct location), and the oldest children successfully implemented the designed action. Findings highlight the perceptual-motor requirements in children's discovery and implementation of the hidden affordances of everyday artifacts.

Compatibility Effects in Young Children's Tool Use: Learning and Transfer

An inherent component of tool-use actions is the transformation of the user's operating movement into the desired effect. In this study, the relevance of this transformation for young children's learning of tool-use actions was investigated. Sixty-four children at the age of 27-30 months learned to use levers which either simply extended (compatible transformation) or reversed (incompatible transformation) their operating movements. Data revealed a compatibility effect as well as transfer effects originating from the two different types of transformations. Furthermore, results suggest that young children's tool-use learning is not a uniform process, but has to be regarded individually depending on the type of transformation.

Let's Cross the Next One: Parental Scaffolding of Prospective Control Over Movement

This investigation examined parental scaffolding of children's prospective control over decisions and actions during a joint perception-action task. Parents and their 6-, 8-, 10-, and 12-year-old children (N = 128) repeatedly crossed a virtual roadway together. Guidance and control shifted from the parent to the child with increases in child age. Parents more often chose the gap that was crossed and prospectively communicated the gap choice with younger than older children. Greater use of an anticipatory gap selection strategy by parents predicted more precise timing of entry into the gap by children. This work suggests that social interaction may serve as an important experiential mechanism for the development of prospective control over decisions and actions in the perception-action domain.

Motion tracking in developmental research: Methods, considerations, and applications

In this chapter, we explore the use of motion tracking methodology in developmental research. With motion tracking, also called motion capture, human movements can be precisely recorded and analyzed. Motion tracking provides developmental researchers with objective measurements of motor and (socio-)cognitive development. It can further be used to create carefully-controlled stimuli videos and can offer means of measuring development outside of the lab. We discuss three types of motion tracking that lend themselves to developmental applications. First, marker-based systems track optical or electromagnetic markers or sensors placed on the body and offer high accuracy measurements. Second, markerless methods entail image processing of videos to track the movement of bodies without participants being hindered by physical markers. Third, inertial motion tracking measures three-dimensional movements and can be used in a variety of settings. The chapter concludes by examining three example topics from developmental literature in which motion tracking applications have contributed to our understanding of human development.

Look before you fit: The real-time planning cascade in children and adults

Goal-directed actions involve problem solving-how to coordinate perception and action to get the job done. Whereas previous work focused on the ages at which children succeed in problem solving, we focused on how children solve motor problems in real time. We used object fitting as a model system to understand how perception and action unfold from moment to moment. Preschoolers (N = 25) and adults (N = 24) inserted three-dimensional objects into their corresponding openings in a "shape-sorting" box. We applied a new combination of real-time methods to the problem of object fitting-head-mounted eye tracking to record looking behaviors, video microcoding to record adjustments in object orientation between reach and insertion, and real-time analysis techniques (recurrent quantification analysis and Granger causality) to test the timing relations between visual and manual actions. Children, like adults, solved the problem successfully. However, adults outperformed children in terms of their speed of fitting, and speed depended on when adjustments of object orientation occurred. Adults adjusted object orientation during transport, whereas children adjusted object orientation after arriving at the box. Children's delays in adjustment resulted from delays in looking at the target shape and its corresponding aperture. Findings show that planning is a real-time cascade of perception and action, and looking provides the basis for planning actions prospectively. We suggest that developmental improvements in problem solving are driven by real-time changes in the instigation of the planning cascade and the timing of its components.

Kinematic characteristics of second-order motor planning and performance in 6- and 10-year-old children and adults: Effects of age and task constraints

This study explored age-related differences in motor planning as expressed in arm-hand kinematics during a sequential peg moving task with varying demands on goal insertion complexity (second-order planning). The peg was a vertical cylinder with either a circular or semicircular base. The task was to transport the peg between two positions and rotate it various amounts horizontally before fitting into its final position. The amount of rotation required was either 0°, 90°, 180°, or -90°. The reaching for the peg, the displacement of it, and the way the rotation was accomplished was analyzed. Assessments of end state comfort, goal interpretation errors, and type of grip used were also included. Participants were two groups of typically developing children, one younger (M_age  = 6.7 years) and one older (M_age  = 10.3 years), and one adult group (M_age  = 34.9 years). The children, particularly 6-year-olds, displayed less efficient prehensile movement organization than adults. Related to less efficient motor planning, 6-year-olds, mainly, had shorter reach-to-grasp onset latencies, higher velocities, and shorter time to peak velocities, and longer grasp durations than adults. Importantly, the adults rotated the peg during transport. In contrast, the children made corrective rotations after the hand had arrived at the goal.

Developmentally Changing Attractor Dynamics of Manual Actions with Objects in Late Infancy

Human infants interact with the environment through a growing and changing body and their manual actions provide new opportunities for exploration and learning. In the current study, a dynamical systems approach was used to quantify and characterize the early motor development of limb effectors during bouts of manual activity. Many contemporary theories of motor development emphasize sources of order in movement over developmental time. However, little is known about the dynamics of manual actions during the first two years of life, a period of development with dramatic anatomical changes resulting in new opportunities for action. Here, we introduce a novel analytical protocol for estimating properties of attractor regions using motion capture. We apply this new analysis to a longitudinal corpus of manual actions during sessions of toy play across the first two years of life. Our results suggest that the size of attractor regions for manual actions increases across development and that infants spend more time inside the attractor region of their movements during bouts of manual actions with objects. The sources of order in manual actions are discussed in terms of changing attractor dynamics across development.

Disappearance of Biased Visual Attention in Infants: Remediated Tonic Neck Reflex or Maturating Visual Asymmetry?

Typically, infants younger than four months fail to attend to the left side of their spatial field, most likely due to an innate asymmetrical tonic neck reflex (ATNR). In a critical transition, by four months of age, infants begin to reach and develop depth perception; and, by five months, they tend to monitor the entire spatial field. However, this developmental transition can be delayed. Moreover, there is always a residual right-sided spatial bias under cognitive load, a phenomenon that may also occur among adult stroke patients. While causative factors of biased visual attention in both infants and brain-injured adults may vary, mechanisms of remediation may be similar. This literature review addresses whether the infant's emergence of attention toward a full visual spatial field and the associated shift from monocular to binocular vision occurs because of (a) increased left side reaching, loosening the rarely mentioned high muscle tension ATNR or (b) maturational resolution of visual asymmetry in motion perception. More research is needed to investigate the origins of the infants' visual control system and factors involved in its development, especially because Alzheimer and dementia patients may also show primitive two-dimensional vision and deficits in perceiving objects-in-motion that seem to mirror infant visual perception.

The Development of Object Fitting: The Dynamics of Spatial Coordination

Fitting objects into apertures is an adaptive skill that is incorporated into the design of many tools. We match or align shapes with openings when we insert keys into locks, when we put lids atop containers, or when we align a screwdriver with the groove of a screw. Traditionally, the development of object fitting has focused on children's abilities to successfully complete shape sorter tasks (e.g., square peg through square hole). By measuring children's success in these tasks, investigators have determined that there is substantial development during the second year, but little research has addressed the processes children employ to solve object fitting challenges during this time period. Here, we provide a process based account of object fitting, which emphasizes how children coordinate information about spatial structure with action. We suggest that a process-based approach can illuminate the real-time dynamics of perceiving, acting, and thinking.