n The First Two Years: Biosocial Development
n Slides prepared by Kate Byerwalter, Ph.D., Grand Rapids Community College
n Body Changes
n An average newborn is 7½ lbs, 20 inches.
n Infants triple their birthweight by 1 year.
n By age two, they are about ½ their adult height (!) and ¼ their adult weight.
n Body Changes
n Body Changes (cont.)
n Percentile ranks: allow comparisons of an individual infant to group norms
¨ A sudden drop in percentile rank might indicate a developmental problem.
n Head Sparing: in cases of inadequate nutrition, the brain keeps growing
n Advantages to breast feeding:
n Nutritionally balanced, antibodies/ illnesses ,$, convenient, bonding, SIDS, IQ, mother’s body
n The Wonderful World of SLEEP
n Newborns sleep 17+ hours a day.
n Students sleep through 100% of Mr. Sheppard’s lectures
n Infant Sleep (cont.)
n Infants gradually adjust to the family’s sleep schedule.
¨ 80% of 1 year olds sleep “through the night”
¨ Sleep cycles are influenced by brain maturation, diet, child-rearing practices, and birth order
n Make It Real: Co-Sleeping
n Some families practice “co-sleeping,” in which the family shares a bed.
n Why might a family do this? Do you think it could benefit or harm an infant?
n Research on Co-Sleeping
n CULTURE influences the decision (it is more common in Eastern culture)
n It is not harmful to an infant, under normal circumstances (e.g., if adult is not drunk)
n It may increase dependence on parents
n Brain Development
n Brain development during infancy is fascinating and rapid.
¨ By the age of 2, the brain is 75% its adult weight
¨ Neural connections in the brain also develop
n Brain Development (cont.)
n Regional specialization: neurons in certain areas of the brain correspond to different tasks
¨ Examples: language, vision, smell, emotional processing, recognizing faces vs. objects, etc.
n The Developing Cortex
n Brain Development (cont.)
n Transient exuberance: rapid proliferation of new neural connections in infancy
¨ As many as 15,000 new connections per neuron and 100 trillion synapses by age 2!
n Pruning makes the brain more efficient by eliminating underused connections.
n What influences early brain development?
n Brain development is influenced by maturation and experiences.
n Experience-expectant brain functions require basic common experiences.
¨ Example: No matter where an infant lives, he or she hears sounds and language.
n What influences early brain development? (cont.)
n Experience-dependent brain functions depend on exposure to particular events.
¨ Example: The particular sounds and language heard (and learned) varies across infants.
¨ Example: The development of impulse control depends on both maturation and practice.
n Why are neural connections so important?
n A certain level of neural connections indicate healthy brain development.
n Lack of connections may result from child abuse or neglect early in life, and can have lasting consequences.
¨ Example: Infants in orphanages
n Implications for Caregivers
n Is it possible to overstimulate an infant? YES!
n The key is to follow the infant’s lead
n Self-righting: an infant’s inborn drive to use whatever experiences available to develop the brain (wow!)
n Infant Senses
n All five senses function at birth
¨ Vision, hearing, taste, touch, smell
n Perception (the brain’s processing of the sensation) develops over time.
n Infant Senses (cont.)
n Hearing: is well developed at birth
¨ Infants respond to sudden noises, human voice, phonemes of language
n Vision: is the least mature sense at birth
¨ Bionocular vision develops around 14 weeks
¨ “Adult” vision (20/20) by one year
n Infant Senses (cont.)
n Taste, touch, smell function well at birth
n Motor Skills
n Motor skills develop according to two principles:
¨ Cephalocaudal: growth proceeds from head-to-toe (e.g., head lift before sit, stand, walk)
¨ Proximal-distal: growth proceeds from torso outward (e.g., sucking before kicking)
n Motor Skills (cont.)
n Reflexes account for the first motor skills.
n Survival reflexes include sucking, breathing, body temperature.
n Other reflexes include the Babinski, Moro, and stepping reflexes.
n Infant Reflexes
n : Motor Skills
n At what age do you think most infants learn to walk?
n What about you?
n Motor Skills (cont.)
n Gross motor skills involve large muscle movements.
¨ Examples: crawling, sitting, walking
¨ Walking typically occurs around 12 months, with great variability across infants.
¨ Walking requires muscle strength, brain maturation, and practice.
n Motor Skills (cont.)
n Fine motor skills involve small muscle movements.
¨ Examples: learning to grasp, shake, pull an object, hold a spoon, write, draw, etc.
n Motor skills are influenced by genes, culture, and patterns of infant care.
n Public Health Measures
n Infant survival rates have increased significantly in the past century, due to better nutrition, cleaner water, and immunization.
n Although not without controversy, immunization has been hailed as a major achievement (e.g., significantly reducing polio, small pox, measles).
n Sudden Infant Death Syndrome
n SIDS is infant death of an unknown cause.
n Protective factors (although not a guarantee) include: NO cigarette smoke in house, noise and touch during sleep, breast feeding, sleeping on back