Motor Development in Infants and Toddlers

Learning Objectives

By the end of this section, you will be able to:

• Describe infants’ reflexes
• Identify the typical milestones of motor development
• Distinguish between gross and fine motor development
• Explain influences on motor development in infancy and toddlerhood

Mateo and Jonas brought their eight-month-old daughter Bella to her pediatrician. Bella has been sitting independently for a couple of months and tries to pull herself up to a standing position, but she shows no interest in crawling. The pediatrician says there is no reason for concern. There are many important milestones in physical development, she says, but crawling is not one of them. This is quite surprising news to both dads. In fact, some babies never crawl: they go straight from sitting to walking. Others scoot on their bottoms, “commando” crawl on their bellies, or adopt a “crab crawl,” placing their weight on one leg while bending the other to propel themselves forward. The pediatrician says that not crawling will not prevent Bella from reaching other important physical milestones like standing and walking.

The first two years of life bring dramatic gains in the development of movement and motor skills. A newborn’s involuntary movements transform to the infant’s ability to exert some limited control over their muscles. Suddenly, that infant is a two-year-old child who loves running, jumping, and climbing.

Newborn Reflexes

Babies are born with several reflexes (Table 3.5). Some, like coughing, sneezing, and blinking, stay with us, while others, like rooting, disappear.

Reflex	Description	Average Age at Which Reflex Disappears
Stepping	Makes stepping motion when sole of feet touches hard surface	2 months
Moro	Arms fling sideways with palms up as if in falling motion	2–4 months
Rooting	Turns head to side, opens mouth wide, and makes sucking motions when stroked on cheek	3–4 months
Palmar grasp	Grasps a finger placed in palm	3–6 months
Swimming	Kicks and makes swimming motions if placed face-down in water	4–6 months
Sucking	Sucks when something is in mouth	4 months
Tonic neck	Assumes fencer stance when relaxed and lying face up if someone turns head to side	6 months
Plantar	Curls toes in when finger is placed below them	9–12 months
Babinski	Toes fan out when foot is stroked	12 months
Blinking	Blinks when eyes touch something or are exposed to sudden brightness	Stays
Coughing	Coughs when airway is stimulated	Stays
Gagging	Gags when back of mouth/throat is stimulated	Stays
Sneezing	Sneezes when nasal passage stimulated	Stays

Why do newborns have reflexes? Some, such as the sucking reflex for nursing or bottle feeding, are for survival. Others are a stress response connected to the sympathetic nervous system. For example, the Moro reflex, also called the startle reflex, is activated when the infant is startled by a sudden movement or noise. The head automatically moves back, and the arms and legs flail out. Other reflexes do not have clear functions but are appealing to see, like the Babinski and plantar reflexes. If you glide your finger on the inner sole of the infant’s foot beneath their toes, the toes curl up, but if you stroke the outer sole, the toes spread out (Figure 3.12).

Figure 3.12 Newborn reflexes include (a) the Moro reflex, similar to a falling response; (b) the palmar reflex when infants grasp an object in their palm; (c) the rooting reflex; and (4) the tonic reflex. (credit a: modification of work “Moro reflex” by “Patty 2”/Wikimedia Commons, Public Domain; credit b: modification of work “Baby” by “NappyStock”/nappy, Public Domain; credit c: “Alden” by Diana Riser/Flickr, CC BY 4.0; credit d: modification of work “Asymmetrical tonic neck reflex (ATNR) at Two Months” by “Mjlissner”/Wikimedia Commons, CC0 1.0)

Some reflexes may be absent in newborns who have neurological impairments or who were born preterm, for example, while others may remain beyond the typical age of disappearance. Health-care professionals are likely to check for the appearance and disappearance of various reflexes to better understand how infants are developing and provide early intervention when needed (Swapna et al., 2020). This scan often begins with the Apgar test immediately after birth.

Milestones in Motor Development

Motor development milestones in the first two years of life are rapid and dramatic, and parents and caregivers often eagerly anticipate their child’s learning to sit, stand, and walk. Each achievement occurs during a given time span. The average age for walking is twelve months, for example, but infants can begin to walk as early as eight months or as late as seventeen to eighteen months. These milestones follow the predictable sequence of cephalocaudal and proximodistal development. For example, following the cephalocaudal pattern, infants are first able to hold their heads up, then sit, pull up, and finally walk. In the proximodistal pattern, infants can grab an object with their full hand before they can manipulate it with individual fingers.

Gross Motor Skills

Voluntary movements that rely on large muscle groups and typically activate the arms, legs, head, and torso are gross motor skills. Infants reach several major postural milestones in the first year (Table 3.6). Movement skills also typically build on one another. For example, after crawling, infants may pull themselves up and then gain the strength to walk. If a child is lagging on one or more milestones, the delay can be addressed through early intervention and monitored by a pediatrician. However, motor milestones also show cultural, experiential, and individual variability (Adolph & Hoch, 2019).

Muscle Control Milestone	Age Range Expected
Supports head	6–8 weeks old
Lifts head and chest when on tummy	2–5 months
Rolls from tummy to back	4–6 months
Sits alone (unsupported)	4–8 months
Stands with support	5–12 months
Stands without support	7–17 months
Walks with support	6–13 months
Walks without support	8–17 months

Link to Learning

During the first few months of life, infants are rapidly moving from one gross motor milestone to the next. This video shows some of the motor milestones they reach during the first three months.

Fine Motor Skills

Although gross motor skills typically appear first, infants and toddlers are also beginning to develop fine motor skills, coordinated movements performed by small muscles to manipulate and control objects or perform precise tasks like reaching for and grasping an object (Table 3.7). Finger movements readily come to mind, but the toes, eyes, face, tongue, and lips also execute fine motor movements.

Fine Motor Skill Milestone	Average Age Expected
Opens hands briefly	2 months
Holds a toy when put in their hand	4 months
Brings hand to mouth	4 months
Reaches to grab toy	6 months
Bangs objects together	9 months
Transfers objects between hands	9 months
Grasps with two fingers	12 months
Feeds self with fingers	18 months
Tries to use buttons or switches on a toy	24 months

Like gross motor skills, fine motor skills often develop in a predictable sequence. At about four months of age, the infant uses two hands to reach for an object and then with more experience uses only one arm. Grasping begins with hands and palms (no thumb), a skill called the ulnar grasp. At about six months, the palmar grasp reflex is replaced by voluntary grasping. Infants begin to use their thumbs at around nine months of age when they grasp with their forefinger and thumb (Figure 3.13), dramatically improving the ability to control and manipulate objects. These coordinated actions are quite an accomplishment in only a few months’ time.

Figure 3.13 One indicator that an infant may be ready for solid food is the ability to pick it up with their fingers for self-feeding. This usually happens by twelve months. (credit: modification of work “20210805-FNS-UNC-0024” by U.S. Department of Agriculture/Flickr, Public domain)

The development of fine motor skills improves with practice, as you can observe if you watch an infant pick up objects and put them into a container repeatedly. With practice, infants will change their grasping patterns to fit the shape and size of the objects (Barrett et al., 2008). Fine motor skills, much like gross motor skills, also show variability based on family environment, culture, and opportunities to practice various movements (Hoch et al., 2024). For example, being in a home with more access to toys that call upon fine motor skills predicts improved fine motor skills.

Motor skills are also the result of interactions with other domains of development. For example, infants must plan and use their senses to move about in their environment. The ability to speak is also dependent on their being able to control the muscles in their mouth and larynx. In addition, although motor skills may appear to develop as individual skills, they build on each other, with each new one serving as the foundation for the next. As infants get older, individual motor skills combine into more complex skills, allowing infants to explore and learn about their surroundings.

Link to Learning

The development of fine motor skills during infancy allows infants to feed themselves and explore their environment. Many of these skills are learned through play.

Motor Development as a Dynamic System

One theory that has helped developmental psychologists understand the complexities of motor development is dynamic systems theory, which posits that developmental behaviors and milestones are the result of interactions between systems, including those within the individual. According to the original theorist, Esther Thelen, motor development is the result of interactions between internal developmental domains (e.g., cognition and the senses), maturation, and the environment (Fujihira & Taga, 2023; Thelen & Smith, 2007). For example, to walk, a child must have several coordinated and developed internal systems including balance, leg muscles, stepping movements, coordination, vision, and spatial awareness (Thelen & Ulrich, 1991).

From a dynamic systems perspective, every motor skill results from multiple maturational and environmental processes. For example, growth in the cerebellum, which contributes to balance and coordination, myelination of the nervous system, and synaptic pruning are critical for acquiring both fine and gross motor skills (Morizawa et al., 2022; Tiemeier et al., 2010). Gross motor skills are also influenced by genetics. Identical twins, who have nearly identical genetic makeup, are more similar in the timing of their motor milestones than fraternal twins, who share around half of the same genes (Ooki, 2006). However, even identical twins have unique experiences that can result in very different motor skill capabilities, as developmental psychologist and neurobiologist Myrtle McGraw observed in case study experiments in the 1930s (McGraw, 1935; Parnin, 2022).

Dynamic systems theory has since expanded into a dynamic systems approach, applying the theory to other domains of development over the lifespan, including cognition and language (Fogel, 2011; Spencer et al., 2011). You may notice that this approach incorporates many of the theories you learned about in Chapter 1 Lifespan Psychology and Developmental Theories, such as cognitive development and behavioral genetics.

Link to Learning

Review this video to observe some of the original footage of Myrtle McGraw’s twin study of motor development.

Experience and Motor Development

While the dynamic systems approach improves our understanding of the influences of systems within the individual, ecological systems and sociocultural theories inform our view of the factors outside the individual that shape developmental outcomes. These can come from cultural and familial environments as well as from individual play behaviors and resources.

Although the sequence of motor milestones is expected to be similar for all children, the timing and abilities can vary widely, demonstrating that environmental and cultural factors play an important role (Adolph & Hoch, 2019). For example, in Tajikistan, infants are regularly swaddled and placed in gahvora cradles for long periods of time. Because of their temporary immobility, these infants reach motor milestones later (Karasik et al., 2018).

In Northern China, where infants lie on their backs with their body movement restricted by being buried in a bag of fine sand for most of the day for toileting practice, the onset of sitting, crawling, and walking is delayed by several months (Mei, 1994). In other cultures, such as in the United States, Argentina, South Korea, and Italy, infants spend a lot of time sitting with postural support from furniture (United States and Argentina) or their mother’s arms (South Korea and Italy) (Karasik et al., 2015). In contrast, infants in Western Kenya have more practice with both supported and independent sitting, which may allow them to sit independently somewhat earlier than in cultures where infants are provided with a lot of support while sitting (Karasik et al., 2015).

Crawling and walking also show great variability based on culture and parenting beliefs. In some cultures, infants skip crawling or walk before they crawl, based on factors like maternal handling, cultural beliefs, and whether parents encourage or discourage crawling (Adolph et al., 2018; Super, 1976). Parenting beliefs can also influence the way they handle their infants. In some cultures, caregivers perform exercises to encourage motor development that might be viewed as rough in another culture (Adolph et al., 2018).

In another example, research following the Back to Sleep campaign has shown that infants placed on their backs while sleeping reach some motor milestones significantly later than infants who slept on their stomachs (Brouwer et al., 2006; Johnson, 2004). In response, pediatricians began encouraging parents to give their infants “tummy time,” which is associated with earlier development of gross motor skills such as walking, standing, and sitting (Hewitt et al., 2020).

Play

Play uses motor skills and cognitive skills, both connected to brain development. For example, with time and practice, the infant who begins by grasping a spoon is soon able to use it as a tool for eating. Besides the physical ability required to do this, the child also uses cognitive skills to play. Using paintbrushes, crayons, balls, and blocks in play takes similar planning and coordination. By one year, the child can point to objects of interest, use more motor skills to explore environments, and interact more with others during playtime. At eighteen months, the child may seek interaction, enjoy patty-cake, and clap during play. Parents and caregivers can support motor development through play by providing age-appropriate toys and activities and encouraging exploration and movement in a safe, supportive environment (Table 3.8).

Play Activity	Motor Development	Age Range
Tummy time	Spending supervised time on their tummy can help infants strengthen neck and upper body muscles.	Infancy
Baby gym	Playing under a play gym with hanging toys encourages babies to reach and grasp.	Infancy
Mirror play	Playing with a baby-safe mirror encourages visual tracking and body awareness.	6 months–2 years
Crawling tunnel	Crawling through a toy tunnel promotes mobility and exploration.	6 months–1 year
Puzzles and building blocks	Interacting with age-appropriate puzzles and soft building blocks improves problem-solving skills, hand-eye coordination, and gross and fine motor skills.	6 months–2 years
Dance and music	Moving to music strengthens balance and coordination.	6 months–2 years
Arts and crafts	Finger painting, coloring, and cutting with safety scissors promote fine motor skills and creativity.	1–2 years
Obstacle courses	Engaging with a simple obstacle course with cushions, pillows, and tunnels encourages crawling, climbing, and balance.	1–2 years
Puppet shows	Interacting with puppets enhances visual tracking and fine motor skills.	1–2 years

Play starts in infancy and can inform several aspects of early development including motor skills, social interaction, self-exploration, and exploration of the environment. Play also helps caregivers and health-care providers observe how well development is progressing.