1: Describe how an infant's gross motor skills develop over the first year.
These skills emerge directly from reflexes and proceed in a cephalocaudal (head-down) and proximodistal (center-out) direction. Infants first control their heads, lifting them up to look around. Then they control their upper bodies, their arms, and finally their legs and feet.
Sitting develops gradually; it is a matter of developing the muscles to steady the top half of the body. By 3 months, most babies can sit propped up in someone’s lap. By 6 months, they can usually sit unsupported. Crawling is another example of the head-down and center-out direction of skill mastery. When placed on their stomachs, many newborns reflexively try to lift their heads and move their arms as if they were swimming. As they gain muscle strength, infants wiggle, attempting to move forward by pushing their arms, shoulders, and upper bodies against whatever surface they are lying on.
Usually by 5 months, infants add their legs to this effort, inching forward (or backward) on their bellies. Exactly when this occurs depends partly on how much “tummy time” the infant has had, which is affected by culture (Zachry & Kitzmann, 2011).
Between 8 and 10 months after birth, most infants lift their midsections and crawl (or creep, as the British call it) on “all fours”, coordinating the movements of their hands and knees. Crawling depends on experience as well as maturation. Some normal babies never do it, especially if the floor is cold, hot, or rough, or if they have always lain on their backs (Pin et al., 2007) It is not true that babies must crawl to develop normally.
All babies find some way to move before they can walk (inching, bear-walking, scooting, creeping, or crawling), but many resist being placed on their stomachs (Adolph & Berger, 2005) Overweight babies master gross motor skills later than thinner ones: Practice and balance is harder when the body is (Slining et al., 2010). As soon as they are able, babies walk, falling frequently but getting up undaunted and trying again, because walking is much quicker than crawling, and it has another advantage--- free hands (Adolph et al., 2012).
The dynamic system underlying every motor skill has three interacting elements. We illustrate those three here with walking.
1. Muscle strength. Newborns with skinny legs and 3-month-olds buoyed by water make stepping movements, but 6-month-olds on dry land do not; their legs are too chubby for their underdeveloped muscles. As they gain strength they stand and then walk.
2. Brain maturation. The first leg movements---kicking (alternating legs at birth and then both legs together or one leg repeatedly at about 3 months) ---occur without much thought. As the brain matures, deliberate leg action becomes possible.
3. Practice. Unbalanced, wide-legged, short strides become a steady, smooth gait.
The last item, practice, is powerfully affected by care-giving before the first independent step. Some adults spend hours helping infants walk (holding their hands or the back of their shirts) or providing walkers (dangerous if not supervised).
Once toddlers are able to walk by themselves, they practice obsessively, barefoot or not, at home or in stores, on sidewalks or streets, on lawns or in mud. They fall often, but that does not stop them---“they average between 500 and 1,500 walking steps per hour so that by the end of each day, they have taken 9,000 walking steps and traveled the length of 29 football fields” (Adolph et al., 2003, p. 494).
2: Describe how a baby's hand skills develop over the first two years.
During their first 2 months, babies excitedly stare and wave their arms at objects dangling within reach. By 3 months, they can usually touch such objects, but they cannot yet grab and hold on unless an object is placed in their hands, because of limited eye—hand coordination
By 4 months, infants sometimes grab, but their timing is off: They close their hands too early or too late. Finally, but 6 months, with a concentrated, deliberate stare, most babies can reach, grab, and grasp almost any object that is of the right size. Some can even transfer an object from one hand to the other. Almost all can hold a bottle, shake a rattle, and yank a sister’s braids. Toward the end of the first year and throughout the second, finger skills improve as babies master the pincer movement (using thumb and forefinger to pick up tiny objects) and self-feeding (first with hands, then fingers, then utensils) (Ho, 2010). (See At About This Time.)
As with gross motor skills, fine motor skills are shaped by culture and opportunity. For example, when given “sticky mittens” (with Velcro) that allow grabbing, infants master hand skills sooner than usual. Their perception advances as well (Libertus et al., 2010; Soska et al., 2010). As with the senses, each motor skill expands the baby’s cognitive awareness.
In the second year, grasping becomes more selective. Toddlers learn when not to pull at a sister’s braids or Mommy’s earrings, or Daddy’s glasses.
3: What is the relationship among perception, sensation, and cognition?
Perception follows sensation, when sensory stimuli are interpreted in the brain. They cognition follows perception, when people think about what they have perceived. (Later, cognition no longer depends on sensation: People imagine, fantasize, and hypothesize.) The sequence from sensation to perception to cognition requires that an infant’s sense organs function.
4: Why did Piaget call his first stage of cognition sensorimotor intelligence?
Because most infants think by using their sense and motor skills during the first stage.
5: What is Chomsky's theory about how young children learn language?
Chomsky labeled this hypothesized mental structure the language acquisition device (LAD). The LAD enables children, as their brains develop, to derive the rules of grammar quickly and effectively from the speech they hear every day, regardless of whether their native language is English, Thai, or Urdu.