The First Two Years: Biosocial Development

The First Two Years: Biosocial DevelopmentSlides prepared by Kate Byerwalter, Ph.D., Grand Rapids Community College The Developing Person Through Childhood and Adolescence by Kathleen Stassen BergerChapter 5Seventh Edition

Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5

Body ChangesAn average newborn is 7 lbs, 20 inches.

Infants triple their birthweight by 1 year.

By age two, they are about their adult height (!) and their adult weight.


Body ChangesALL: INES YVETTE LARAYA ERESE


Body Changes (cont.)Percentile ranks: allow comparisons of an individual infant to group norms

A sudden drop in percentile rank might indicate a developmental problem.

Head Sparing: in cases of inadequate nutrition, the brain keeps growing


The Wonderful World of SLEEPNewborns sleep 17+ hours a day.DAVID YOUNG-WOLFF / PHOTOEDIT, INC.


Infant Sleep (cont.)Infants gradually adjust to the familys sleep schedule.

80% of 1 year olds sleep through the nightSleep cycles are influenced by brain maturation, diet, child-rearing practices, and birth order


Make It Real: Co-SleepingSome families practice co-sleeping, in which the family shares a bed.

Why might a family do this? Do you think it could benefit or harm an infant?


Research on Co-SleepingCULTURE influences the decision (it is more common in Eastern culture)

It is not harmful to an infant, under normal circumstances (e.g., if adult is not drunk)

It may increase dependence on parents


Brain Development 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



Brain Development (cont.)Regional specialization: neurons in certain areas of the brain correspond to different tasks

Examples: language, vision, smell, emotional processing, recognizing faces vs. objects, etc.


The Developing Cortex


Brain Development (cont.)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!

Pruning makes the brain more efficient by eliminating underused connections.



What influences early brain development? Brain development is influenced by maturation and experiences.

Experience-expectant brain functions require basic common experiences.

Example: No matter where an infant lives, he or she hears sounds and language.


What influences early brain development? (cont.)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.


Why are neural connections so important? A certain level of neural connections indicate healthy brain development.

Lack of connections may result from child abuse or neglect early in life, and can have lasting consequences.

Example: Infants in orphanages


Make it Real: ActivitiesMake a list of toys and activities that can stimulate healthy brain development in the first two years of life.PHOTODISC


Implications for CaregiversIs it possible to overstimulate an infant? YES!

The key is to follow the infants lead

Self-righting: an infants inborn drive to use whatever experiences available to develop the brain (wow!)


Infant SensesAll five senses function at birthVision, hearing, taste, touch, smell

Perception (the brains processing of the sensation) develops over time.


Infant Senses (cont.)Hearing: is well developed at birthInfants respond to sudden noises, human voice, phonemes of language

Vision: is the least mature sense at birthBionocular vision develops around 14 weeksAdult vision (20/20) by one year


Infant Senses (cont.)Taste, touch, smell function well at birthAll: CINDY CHARLES / PHOTOEDIT, INC.


Motor SkillsMotor 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)


Motor Skills (cont.)Reflexes account for the first motor skills.

Survival reflexes include sucking, breathing, body temperature.

Other reflexes include the Babinski, Moro, and stepping reflexes.


Infant ReflexesJENNY WOODCOCK; REFLECTIONS PHOTOLIBRARY / CORBISPETIT FORMAT / PHOTO RESEARCHERS, INC.ASTIER / BSIP / SCIENCE SOURCE / PHOTO RESEARCHERS, INC.


Make it Real: Motor SkillsAt what age do you think most infants learn to walk?

What about you?PHOTODISC



Motor Skills (cont.)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.


Motor Skills (cont.)Fine motor skills involve small muscle movements.

Examples: learning to grasp, shake, pull an object, hold a spoon, write, draw, etc.

Motor skills are influenced by genes, culture, and patterns of infant care.


Public Health MeasuresInfant survival rates have increased significantly in the past century, due to better nutrition, cleaner water, and immunization.

Although not without controversy, immunization has been hailed as a major achievement (e.g., significantly reducing polio, small pox, measles).



Sudden Infant Death SyndromeSIDS is infant death of an unknown cause.

Protective factors (although not a guarantee) include: NO cigarette smoke in house, noise and touch during sleep, breast feeding, sleeping on back

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The First Two Years: Biosocial Development