ECC Chapter 4 PSY 218 Spring 2015.pptx

Physical Development

in Infancy

Principles of Physical Growth

•

_{Directionality is how body proportions change.}

• Change is generally cephalocaudal (from head to tail) and proximodistal (from the center of the body outward).

• Development occurs in a down and out fashion.

• Eyes mature before legs

• Control of arm precedes control of fingers.

• _{However, not all parts develop at the same time.}

• We have an Independence of systems.

• _{Different parts of the body develop according to different time tables.}

• Children also develop on different time tables as well.

Development of the Central Nervous

System

•

Central Nervous System

• _{Brain and spinal cord.}

• _{Processes information and directs behavior.}

• _{Genetically predetermined brain development leads to new behaviors.}

• These new behaviors lead to new environmental interactions that foster brain development.

•

Subcortical structures in the brain control the state of arousal (e.g., sleep)

and develop first.

•

Components of the limbic system regulate emotion and develop next.

The Brain

•

_{The brain consists of two hemispheres connected by the corpus}

collosum.

•

_{The cortex is the thin layer of tissue covering the brain – contains 75%}

of the brain’s cells.

• _{Nonmammals do not have a cortex.}

The Brain

•

_{Different areas of the cortex have different functions:}

• _{Visual Cortex regulates sight.}

• _{Auditory Cortex regulates hearing.} • _{Sensorimotor Cortex regulates touch.}

• _{Frontal Cortex higher cognitive functions.}

• _{Motor Cortex processes voluntary movement.}

•

_{In the left hemisphere, two small areas exist that are responsible for}

Brain Cells

• _{Information is carried across the body and brain, as well as back and forth}

within the brain, through neurons.

• _{Neurons consist of:}

• Dendrites receive information from other neurons.

• Cell body provides energy for the neuron.

• Axon carries the information away from the cell body to other neurons.

• _{Neuron’s do not touch, but use a synapse to communicate.}

The Brain

•

_{During prenatal brain development, synaptogenesis occurs.}

• _{Axons and dendrites grow making new connections between neurons.}

• _{In the first six months of gestation, over 10,000 new synapses are formed}

each minute.

• _{By two years of age, 1 neuron can have 10,000 conections.}

• _{Peaks around age one but does continue later as new skills are acquired and}

The Brain

•

_{The brain often develops more connections than it can use.}

• _{In this case, Synaptic pruning eliminates unused and unnecessary synapses.}

• Makes the brain more efficient and assists in plasticity.

•

_{Myelination is also vital to brain development.}

• _{Myelin covers axons and increases transmission to the terminal buttons.}

• _{The parts of the brain involved in sensory and motor function are myelinated}

first.

• Our cerebellum becomes myelinated around age four, for example.

• _{Loss of myelination can result in losses of motor control, deterioration of}

The Brain

•

_{Transmission of information between cells is usually spread out, but}

Brain Plasticity

• _{Experience-expectant processes are those in which brain cells are prewired to}

engage.

• _{Experience-dependent processes involve the active formation of new}

synapses based on individual experience. • _{Contributes to our individuality}

• _{Experience dependent processes and exploration of the environment underlie}

brain plasticity.

Brain Plasticity

•

_{Modifiability sometimes occurs during sensitive periods (critical}

points in development).

• _{Brain is so plastic early in life that some cells can be modified to serve a}

completely different purpose.

•

_{Beyond modifiability, a separate type of plasticity is called}

compensation

Autonomic Nervous System

•

_{Regulates bodily activities not under our voluntary control.}

• _{Assists in triggering social activities (e.g., sleep-wake cycle signals to}

caregivers when to initiate play).

•

_{Arousal states are not regular during infancy.}

• _{Regularity reveals maturity of the infant’s nervous system.}

• Poorer regulation is generally common in preterm infants.

• _{An infants arousal state can influence subsequent behavior.}

Reflexes and Motor Development

•

_Reflexes

• _{Simple, involuntary reactions to certain stimuli.}

• Generally have some adaptive significance.

• _{Divided into three types:}

• Approach reflexes- Concerned with intake, such as breathing or sucking.

• Avoidance reflexes – All or nothing characteristics, such as sneezing or blinking.

• Other reflexes- meant more in our evolutionary past, such as Palmer grasp and Moro response.

Reflexes and Motor Development

•

_{Motor development during infancy depends on both physical}

maturation and experience.

• _{Generally predictable:}

• _{6 months – sitting}

• _{8 to 10 months – crawling} • _{1 year – walking}

•

_{Cultural and parental expectations can influence motor milestones:}

• _{American mothers tend to value crawling, and most American infants do crawl.} • _{Mali and Jamaican mothers do not place the same emphasis on crawling so}

Reflexes and Motor Development

•

_{Dynamic Systems Theory asserts that change in one area of}

development affects other areas of development:

• _{Even though infants have depth perception well before they crawl, it is only}

Sensing and Perceiving

•

_{An infant’s sensory systems begin to function while it is in utero.}

• Allows the infant to “concentrate” on one area of development at a time.

•

_{Newborns are able to see and will actively seek visual stimulation.}

• _{Visual acuity is poor at birth, but near adult levels by six months of age.}

•

_{Infants show a preference for looking at faces.}

Sensing and Perceiving

• _{“Visual Cliff” and depth perception:}

• _{Very few infants at 6-14 months of age will crawl across the cliff, suggesting they have some fear}

of falling, suggesting a fear.

• _{Other research indicates that babies perceive depth long before they show a fear of falling.}

• _{By 3.5 months infants generally recognize different directions of motion.}

• By 5 months, they can discriminate rotation (turning in a circle) from oscillation (swaying side-to-side).

• Important because movement perception is important in object recognition.

• _{By 2 months, infants generally see colors well and perceive colors as adults do by 4}

Sensing and Perceiving

•

_{Fetuses respond to sound around the third month of gestation.}

• _{They hear well at birth and are especially sensitive to sound frequencies that}

match human voices.

•

_{Infants quickly begin to apply hearing to decipher speech.}

• _{Adults tend to use infant-directed speech, like “motherese” when speaking}

with babies.

Sensing and Perceiving

•

By 6 months, infants generally begin reaching for most things in sight.

• _{Touch is important to an infant’s ability to learn about the world.}

•

Infants are highly responsive to tactile stimulation.

• _{Touch is vital to establishing emotional intimacy.}

• Harlow’s monkeys

•

Infants show different facial expressions for sweet, sour, salty, and bitter

flavors.

Sensing and Perceiving

•

_{The sense of smell is well developed at birth.}

• _{Some odors elicit positive responses while others elicit negative responses.}

• Newborns that are breasted can identify their mother’s odor.

Multi- and Cross- modal Perception

•

_{Sensory systems do not function in isolation.}

• _{Multimodal Perception}

• Perception of objects and events in the world that stimulate many senses at once.

• Learning about something via one sense is enhanced by experiencing it in another as well. • In a study, infants were able to identify a pacifier by sight, although they had

experienced it only by sucking on it previously.

• This is an example of Crossmodal Perception

Experience and Early Perceptual

Development

•

_{Although infants’ perceptual abilities are relatively well organized at}

birth, perceptual experience is very important as well.

• _{For example, infants whose mothers smiled at lot showed more sensitivity to}

smiling faces in laboratory settings.

•

_{Perceptual development in infancy provides multiple examples of the}

interplay between biology and experience:

• _{The developing brain and CNS collaborate with the sensory systems to allow}