What is motor skill development?

Physical and Psychological Factors

Motor skill development, the process of change in motor behavior with increasing age, focuses on adjustments in posture, movement, and the skillful manipulation of objects. Early researchers attributed essentially all developmental changes to modifications occurring within the central nervous system, with increasing motor abilities reflecting increasing neural maturation. Modern researchers have determined that the central nervous system works in combination with other body systems (such as the musculoskeletal, cardiovascular, and respiratory systems) and the environment to influence motor development, with all systems interacting in an extremely complex fashion as the individual ages.

Prenatal development of motor behavior takes place between approximately seven weeks after conception and birth, as was first determined during the 1970s using technology to visualize the fetus in utero. Following approximately eight weeks of gestation, the fetus is able to exert reflex and reaction actions, as well as active spontaneous movement. It is currently believed that the ability to self-initiate movements within the womb is an integral part of development, as compared to the traditional view that the fetus is passive and reflexive.

Infancy, the period from birth until the child is able to stand and walk, lasts approximately twelve months. The neonate begins life essentially helpless against the force of gravity and gradually develops the ability to align body segments with respect both to other body segments and to the environment. The Bayley Scales of Infant Development measure the following milestones of motor skill development for the first year of life (with the average age of accomplishment listed in parentheses): erect and steady head holding (0.8 months), side to back turning (1.8 months), supported sitting (2.3 months), back to side turning (4.4 months), momentary independent sitting (5.3 months), rolling from back to stomach (6.4 months), steady independent sitting (6.6 months), early supported stepping movements (7.4 months), arm pull to standing position (8.1 months), assisted walking (9.6 months), independent standing (11.0 months), and independent walking (11.7 months). The transition from helplessness to physical independence during the first twelve months creates many changes for growing children and their caregivers. New areas of exploration open up for the baby as greater body control is gained, the force of gravity is conquered, and less dependence on holding and carrying by caregivers is required.

During the first three months after birth, the infant’s motor skill development focuses on getting the head aligned from the predominating posture of flexion. Flexor tone, the tendency to maintain a flexed posture and to rebound back into flexion when the limbs are extended and released, probably results from a combination of the elasticity of soft tissues that were confined to a flexed position while in the womb and of central nervous system activity. As antigravity activity progresses, the infant develops the ability to lift the head. Movements during this period involve brief periods of stretching, kicking, and thrusting of the limbs, in addition to turning and twisting of the trunk and head. Infants tend to be the most active prior to feeding and more quiet and sleepy after feeding.

The third to sixth months after birth are marked by great strides in overcoming the force of gravity by both flexion and extension movements. The infant becomes more competent in head control with respect to symmetry and midline orientation with the rest of the body, is able to sit independently for brief periods, and can push up onto hands and knees. These major milestones enable considerably more independence and permit a much greater ability to interact with the rest of the world.

During the sixth to ninth months after birth, the infant is constantly moving and exploring the surrounding environment. As nine months is approached, most babies are able to pull themselves into a standing position using a support such as furniture. The child expends a great deal of energy to stand and often bounces up and down once standing is achieved. The up-and-down bouncing eventually leads to the shifting of body weight from side to side and the taking of first steps, with a caregiver assisting alongside the furniture; this is often called cruising.

The ninth to twelfth months involve forward creeping on hands and knees. This locomotor pattern requires more complicated alternating movements of the opposite arms and legs. Some infants have a preference for creeping even after they are able to walk independently, with many preferring plantigrade creeping (on extended arms and legs) to walking. The ease to which the child moves from sitting to creeping, kneeling, or standing is greatly improved and balance is developed to the point where the child can pivot around in circles while sitting, using the hands and feet for propulsion. The child begins to move efficiently from standing to floor sitting and can initiate rolling from the supine position using flexed legs. Unsupported sitting is accomplished with ease, and weight while sitting can be transferred easily from buttocks to hands.

The early childhood period lasts from infancy until about six years. It involves the child attaining new skills but not necessarily new patterns of movement, with the learning patterns that were acquired during the first year of life being put to use in more meaningful activities. The locomotor pattern of walking is refined, and new motor skills that require increased balance and control of force—such as running, hopping, jumping, and skipping—are mastered.

Running is usually begun between years two and four, as the child learns to master the flight phase and the anticipatory strategies necessary when there is temporarily no body contact with the ground. It is not until about age five or six that control during running with respect to starting, stopping, and changing directions is effectively mastered. Jumping develops at about age 2.5, as the ability and confidence to land after jumping from a height such as a stair is achieved. The ability to jump to reach an overhead object then emerges, with early jumpers revealing a shallow preparatory crouch that progresses to a deeper crouch. Hopping, an extension of the ability to balance while standing on one leg, begins at about age 2.5 but is not performed well until about age six, when a series of about ten hops can be performed consecutively and are incorporated into games such as hopscotch. Skipping, a step and a hop on one leg followed by a step and hop of the other leg, is generally not achieved until about six years, with the opportunity and encouragement for practice being a primary determining factor, as with other locomotor skills.

Throwing is typically acquired during the first year, but advanced throwing, striking (such as with a plastic baseball and bat), kicking (such as with a soccer ball), and catching are not developed until early childhood. Catching develops at approximately age three, with the child initially holding the arms in front of the body and later making anticipatory adjustments to account for the direction, speed, and size of the thrown object. Kicking, which requires balancing on one foot while transferring force to an object with the other foot, begins with little preparatory backswing and eventually develops to involve the knee, hip, and lean of the trunk at about age six.

Fine motor manipulation skills in the upper extremity that are important to normal activities of daily living such as feeding, dressing, grooming, and handwriting are greatly improved in early childhood. The key components include locating a target, which requires the coordination of eye-head movement; reaching, which requires the transportation of the hand and arm in space; and manipulation, which includes grip formation, grasp, and release.

During later childhood (the period from seven years to about eleven years), adolescence, and adult life throughout the remainder of the life span, changes in movement are influenced predominantly by age. Adolescence begins with the onset of the physical changes of puberty, at approximately eleven to twelve years of age in girls and twelve to thirteen years of age in boys, and ends when physical growth is curtailed. Most authorities believe that the growth spurt of adolescence leads to the emergence of new patterns of movement within the skills that have already been acquired. Most adolescents have strong drives to develop self-esteem and become socially acceptable with their peers in school and various recreational activities. Cooperation and competition become strong components of motor skill development, whereby many skills are stabilized prior to adolescence and preferences for various sports activities emerge. Boys typically demonstrate increased speed and strength as compared to girls, despite recent dramatic changes in available opportunities for girls in recreational and competitive sports activities. Even though age-related changes in motor behavior continue throughout adulthood, the physical skills that permit independence are primarily acquired during the first year of life.

Psychological factors that influence motor skill development include attention level, stimulus-response compatibility, arousal level, and motivation. The level of attention when attempting a motor task is critical, with humans displaying a relatively fixed capacity for concentration during different stages of development. Stimulus identification, response selection, and response programming stages—whereby an individual remembers or determines how to perform a task—affect skill development because the central nervous system takes longer to synthesize and respond to more complex skills. Also important are stimulus-response compatibility—the better the stimulus matches the response, the shorter the reaction time—and arousal, which is described as an “inverted U” by the Yerkes-Dodson model. The inverted U hypothesis implies that there exists an optimal level of psychological arousal to learn or perform a motor skill efficiently, with performance declining when the arousal level at a given moment in time is too great or too small. At a low level of arousal, the scope of perception is broad, and all stimuli (including irrelevant information) are being processed. As arousal level increases, perception narrows so that
when the optimal level of arousal is reached and attention is sufficiently focused, concentration on only the stimuli relevant to successful skill learning and performance is enabled. If arousal level surpasses this optimal level, perception narrows to the point of tunnel vision, some relevant stimuli are missed, and learning and skill performance are reduced. The influence of personal motivation during motor skill development encompasses the child’s perceived relevance of the activity and also the child’s individual ability to recognize the goal of the activity and desire to achieve it.

Three main factors that affect motor skill development in early and later childhood include feedback, amount of practice, and practice conditions. Feedback can be intrinsic, arising from the somatosensory system and senses such as vision and hearing, as information is gathered about a movement and its consequences rather then the actual achievement of the goal. In pathological conditions such as cerebral palsy, intrinsic feedback is often greatly impaired. Feedback can also be extrinsic and is often divided by researchers into knowledge of results, or information about the success of the movement in accomplishing the goal that is available after the skill is completed, and knowledge of performance, or information about skill performance technique or strategy. Knowledge of results provides information about errors as well as successes. True learning occurs by a process of trial and error, with the nervous system serving to detect and correct inappropriate or inefficient movements.

Disorders and Effects

Physical therapists, psychologists, teachers, and other professionals who work with pediatric patients often plan their treatment interventions and instructional lessons based on the normal age-related progression of motor skill development. Motor skill development is often significantly decreased as a consequence of a neurological impairment, however, with the child’s resulting movement patterns revealing primary impairments such as inadequate activation of muscle, secondary impairments such as contractures, and compensatory strategies that are adopted to overcome the impairment and achieve mobility. The categories for impairments that have an impact on motor development can generally be divided into musculoskeletal, neuromuscular, sensory, perceptual, and cognitive.

Damage to various nervous system structures somewhat predictably reduces the motor control of movement via both positive symptoms (the presence of abnormal behavior) and negative symptoms (the loss of normal behavior). Positive symptoms include the presence of exaggerated reflexes and abnormalities of muscle tone. Negative symptoms include the loss of muscular strength and the inappropriate selection of muscles during task performance. The broad spectrum of muscle tone abnormalities ranges from flaccidity to rigidity, with muscle spasticity defined as the velocity-dependent increase in tonic stretch reflexes (also called muscle tone), with exaggerated tendon jerks resulting from changes in the threshold of the stretch reflex.

Secondary effects of central nervous system lesions are not directly caused by the lesions themselves but develop as a consequence of the lesions. For example, children with cerebral palsy often exhibit the primary problem of spasticity in muscles of the lower extremities, which causes the secondary problem of muscular and tendon tightness in the ankles, knees, and hips. The secondary problem of limited range of motion in these important areas for movement often impairs motor skills more than the primary problem of spasticity, with the resulting movement strategies reflecting the growing child’s best attempt to compensate.

Another common compensatory strategy seen in children with a motor development dysfunction involves standing with the knee hyperextended because of an inability to generate enough muscular force to keep the knee from collapsing. Standing with the knee in hyperextension keeps the line of gravity in front of the knee joint. Contractures of joints are frequent consequences of disordered postural and movement patterns. For example, a habitual crouched sitting posture results in chronic shortening of the hamstring, calf, and hip flexor muscles, and a backward-tipped pelvis accommodates the shortened hamstrings. Chronic shortening of the calf muscles often results in toe walking (in which the heel does not strike the ground) and a reduced walking speed and stride length, because of decreased balance and leg muscle strength. Changes in the availability of sensory information and cognitive factors such as fear of falling and inattention may also contribute strongly to motor skill development in some pediatric patients.

Perspective and Prospects

Interest in the scientific study of motor development was greatly enhanced by Myrtle B. McGraw’s The Neuromuscular Maturation of the Human Infant (1945). It described four stages of neural maturation: a period in which movement is governed by reflexes as a result of the dominance of lower centers within the central nervous system; a period in which reflex expression declines as a result of maturation of the cerebral cortex and the inhibitory effect of the cortex over lower centers; a period in which an increase in the voluntary quality of activity as a result of increased cortical control produces deliberate or voluntary movement; and a period in which integrative activity of the neural centers takes place, as shown by smooth and coordinated movements.

Arnold Gesell then used cinematography to conduct extensive observations of infants during various stages of growth. He described the maturation of infants based on four behavior categories: motor behavior, adaptive behavior, language development, and personal-social development. Gesell identified six principles of development. The principle of motor priority and fore-reference states that the neuromotor system is laid down before it is voluntarily utilized. The principle of developmental direction states that development proceeds in head-to-foot and proximal-to-distal directions. The principle of reciprocal interweaving states that opposing movements such as extension and flexion show a temporary dominance over one another until they become integrated into mature motor patterns. The principle of functional asymmetry states that humans have a preferred hand, a dominant eye, and a lead foot, with this unilateral dominance being subject to change during development. The principle of self-regulation states that periods of stability and instability culminate into more stable responses as maturity proceeds. The principle of optimal realization states that the human action system has strong growth potential toward normal development if environmental and cultural conditions are favorable and if compensatory and regeneration mechanisms come into play when damage occurs to facilitate attainment of the maximum possible growth.

Esther Thelen suggested the dynamic systems theory. This theory argues that the maturing nervous system interacts with other biomechanical, psychological, and social environment factors to create a dimensional system whereby behavior represents a compression of the degrees of freedom.

A more refined systems theory of motor control developed by Anne Shumway-Cook and Marjorie Woollacott claims that the three main factors that interact in the development of efficient locomotion are progression (ability to generate rhythmic muscular patterns to move the body in the desired direction), stability (the control of balance), and adaptation (the ability to adapt to changing task and environmental requirements). These three factors generally appear sequentially, with muscular patterns appearing first, followed by equilibrium control, and finally adaptive capabilities. Although research on the emergence of human motor skills has primarily concentrated on the developmental milestones of infants and children, it appears that important changes in motor behavior continue throughout the human life span.

Bibliography

Berk, Laura E. Child Development. 9th ed. Boston: Pearson/Allyn & Bacon, 2013.

Feldman, Robert S. Development Across the Life Span. 6th ed. Upper Saddle River, N.J.: Pearson/Prentice Hall, 2011.

Haywood, Kathleen, Mary Ann Roberton, and Nancy Getchell. Advanced Analysis of Motor Development. Champaign, Ill.: Human Kinetics, 2012.

Kail, Robert V., and John C. Cavanaugh. Human Development: A Life-Span View. 6th ed. Belmont, Calif.: Wadsworth Cengage Learning, 2013.

Kalverboer, Alex F., Brian Hopkins, and Reint Geuze, eds. Motor Development in Early and Later Childhood: Longitudinal Approaches. New York: Cambridge University Press, 1993.

Ludlow, Ruth, and Mike Phillips. The Little Book of Gross Motor Skills. London: Featherstone Education, 2012.

Nathanson, Laura Walther. The Portable Pediatrician: A Practicing Pediatrician’s Guide to Your Child’s Growth, Development, Health, and Behavior from Birth to Age Five. 2d ed. New York: HarperCollins, 2002.

Newell, K. M. “Motor Skill Acquisition.” Annual Review of Psychology 42 (1991): 213–37.

Shumway-Cook, Anne, and Marjorie Woollacott. Motor Control: Translating Research into Clinical Practice. 4th ed. Philadelphia: Lippincott Williams & Wilkins, 2012.

Sugden, David, and Michael G. Wade. Typical and Atypical Motor Development. London: Mac Keith Press, 2013.

Thelen, Esther, and Linda B. Smith. A Dynamic Systems Approach to the Development of Cognition and Action. 5th ed. Cambridge, Mass.: MIT Press, 2002.