The First Two Years:
Biosocial Development
Charles A. Guigno, M.A.
CharlesA.Guigno@kbcc.cuny.edu
Brain Growth
 Head-sparing
 Biological mechanism
 Brain is the last part of the body to be damaged by
malnutrition.
 Protects the brain when malnutrition disrupts body
growth.
 Neurons Connecting
 Communication within the central nervous system,
brain and spinal cord, begins with nerve cells called
neurons.
 The newborn brain has billions of neurons, 70% of
them in the cortex. Most thinking, feeling and
sensing occur in the cortex.
Brain Development
(c) 2012 The McGraw-Hill Companies, Inc.
The Developing Cortex
Brain Development: Dendrites Sprouting
Experience and Pruning
 At birth the brain contains at least 100 billion neurons,
more than a person needs.
 40,000 new synapses are formed every second in the
infant’s brain.
 Brain structure and growth depends on genes and
maturation, but even more on experience.
 Transient exuberance: the great but temporary increase in
the number of dendrites that develop in an infant’s brain
during the first two years of life.
 Expansion and pruning of dendrites occur for every aspect of early
experience.
 Unused dendrites whither to allow space between neurons, allowing
more synapses and thus more complex thinking.
Experience and Pruning (Ct’d)
 Brain sculpting is attuned to experience: the
appropriate links in the brain need to be
established, protected and strengthened while
inappropriate ones are eliminated.
 Some research suggests that infants who are often
hungry, hurt or neglected may develop brains that
compensate and cannot be reprogrammed even if
circumstances change.
 The hungry baby becomes the obese adult
 The abused child rejects attention
Harm and Protection
 Infants need stimulation
 Experience-dependent: brain development is
variable because circumstances vary.
 Experience-expectant: brain development
occurs because of circumstances that all human
babies should have.
 Sensory stimulation: play, sights, sounds,
touches and movements all help with brain
connections.
 Infants are fascinated by simple objects and
facial expressions.
Harm and Protection (Ct’d)
 Infants need protection
 Shaken baby syndrome: a life-threatening injury that
occurs when an infant is forcefully shaken back and
forth, this motion ruptures blood vessels in the brain
and breaks neural connections.
 Stress and the brain
 Overabundance of stress hormones damages later brain
functioning.
 Self-righting: an inborn drive to remedy a
developmental deficit
 Infants with no toys develop their brains using other
objects available.
 Human brains are designed to grow and adapt.
Sleep
 Sleep specifics vary because of biology and
the social environment.
 Newborns sleep about 15-17 hours a day, in
one to three-hour segments.
 Newborns’ sleep is primarily active sleep.
 Newborns have a high proportion of REM
(rapid eye movement) sleep.
 Closed lids, flickering eyes and rapid brain
waves.
 Indicates dreaming.
Perceiving and Moving
 Sensation precedes perception. Perception leads to
cognition.
 Sensation: Response of a sensory system (eyes, ears,
skin, tongue and nose) when it detects a stimulus.
 Every sense functions at birth. Young babies use their
senses to attend to everything without judgment.
 Survival requires babies to respond to people.
 Perception: mental processing of sensory information
when the brain interprets a sensation.
 If a sensation occurs often, it connects with past
experience, making a particular sight worth interpreting
Hearing and Seeing
 Hearing
 Develops during the last trimester of pregnancy
 Most advanced of the newborn’s senses
 Speech perception by 4 months after birth.
 Seeing
 Least mature sense at birth
 Newborns focus between 4-30 inches away
 Experience and maturation of the visual
cortex improve shape recognition, visual
scanning and details.
 Binocular vision at 3 months.
Tasting and Smelling
 Function at birth and rapidly adapt to the
social world.
 Related to family and cultural preferences.
 May have evolutionary function.
 As babies learn to recognize each person’s
scent, they prefer to sleep next to their
caregivers.
Touch and Pain
 Touch
 Sense of touch is acute in infants.
 Wrapping, rubbing, massaging and cradling
are soothing to many new babies.
 Pain
 Pain and temperature are often connected to
touch.
 Some people assume that even the fetus can
feel pain.
 Others say that the sense of pain does not
mature until months or years later.
Motor Skills: Gross Motor Skills
 Motor skill: the learned abilities to move some part
of the body, in actions ranging from a large leap to
a flicker of the eyelid.
 Course of development
 Cephalocaudal (head-down) and
proximodistal (center-out) direction.
 Gross motor skills
 Physical abilities involving large body
movements (walking and jumping)
Dynamic Systems: Motor Skills
 Muscle Strength: As they gain strength they
can stand and then walk.
 Brain Maturation: As the brain matures,
deliberate leg action becomes possible.
 Practice: Unbalanced, wide-legged, short
strides become a steady, smooth gait.
 Powerfully affected by caregiving before the first
independent step.
 http://www.youtube.com/watch?v=acWAnzJTGJE
Motor Skills: Fine Motor Skills
 Fine motor skills: physical abilities involving
small body movements, especially of the hands
and fingers. (mouth movements too)
 Shaped by culture and opportunity
 By 6 months: most babies can reach, grab and
grasp almost any object of the right size.
 Towards the end of the first year and
throughout the second year: babies master the
pincer movement and self-feeding.
Surviving in Good Health
 At least 9 billion children were born between
1950 and 2010; more than 1 billion of them died
before age 5.
 The world death rate in the first five years of
life has dropped about 2 percent per year since
1990.
 Public health measures (clean water,
nourishing food, immunization, medical
treatments)
Sudden Infant Death Syndrome
 Sudden infant death syndrome (SIDS)
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Situation in which a seemingly healthy infant, usually
between 2 and 6 months old, suddenly stops
breathing and dies unexpectedly while asleep.
Beal: Studied SIDS death in South Australia and
concluded factors related to increased risk
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Low birth weight
Sleeping position (Back is best!)
Maternal smoking
Bedding type