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

2. Body Changes An average newborn is 7½ lbs, 20 inches.
Infants triple their birthweight by 1 year.
By age two, they are about ½ their adult height (!) and ¼ their adult weight.

3. Body Changes
ALL: INES YVETTE LARAYA ERESE

4. 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

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

6. Infant Sleep (cont.)
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

7. Make It Real: Co-Sleeping
Some 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?

8. Research on Co-Sleeping
CULTURE 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

9. 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

11. 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.

12. The Developing Cortex

13. 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.

15. 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.

16. 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.

17. 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

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

19. Implications for Caregivers
Is it possible to overstimulate an infant? YES!
The key is to follow the infant’s lead
Self-righting: an infant’s inborn drive to use whatever experiences available to develop the brain (wow!)

20. Infant Senses All five senses function at birth
Vision, hearing, taste, touch, smell
Perception (the brain’s processing of the sensation) develops over time.

21. Infant Senses (cont.) Hearing: is well developed at birth
Infants respond to sudden noises, human voice, phonemes of language
Vision: is the least mature sense at birth
Bionocular vision develops around 14 weeks
“Adult” vision (20/20) by one year

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

23. Motor Skills 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)

24. 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.

25. Infant Reflexes
ASTIER / BSIP / SCIENCE SOURCE / PHOTO RESEARCHERS, INC.
JENNY WOODCOCK; REFLECTIONS PHOTOLIBRARY / CORBIS
PETIT FORMAT / PHOTO RESEARCHERS, INC.

26. Make it Real: Motor Skills
At what age do you think most infants learn to walk?
What about you?
PHOTODISC

28. 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.

29. 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.

30. Public Health Measures
Infant 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).

32. Sudden Infant Death Syndrome
SIDS 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