Chapter 5 - Physical Development in Infancy and Toddlerhood (Brain…
Chapter 5 - Physical Development in Infancy and Toddlerhood
Changes in body proportions
PROXIMODISTAL TREND - refers to growth from the center of the body outward
CEPHALOCAUDAL TREND - refers to growth "from head to tail"
SKELETAL AGE - measure of bone development, best way of estimating a child's physical maturity
How to measure skeletal age? X-ray bones and see the # of epiphyses (special growth centers in bones that make cartilage). Cartilage hardens to bone over time.
Why are girls physically mature than boys?
Experience few developmental problems
Have lower infant and childhood mortality rates
Greater resistance to harmful environmental influences
FONTANELS - soft spots in the skull. Six are present at birth. Gaps permit the bones to overlap as the large head of the baby passes through the mother's birth canal.
Changes in body size and muscle-fat makeup
Baby fat helps to maintain constant body temperature
Sex differences: Girls are slightly shorter and lighter than boys, with a higher ratio of fat to muscle
Infant growth is marked by little spurts between plateau periods
Ethnic differences: Asian babies are smaller than Caucasian babies are smaller than African babies
SYNAPTIC PRUNING: neurons that are seldom stimulated lose their synapses, and return to an uncommitted state so that they can support future development.
MYELINATION: the coating of neural fibers with an insulating fatty sheath that improves the efficiency of message transfer.
EVENT-RELATED POTENTIALS (ERPs): Frequency and amplitude of brain waves in response to particular stimuli are recorded in specific areas of the cerebral cortex.
FUNCTIONAL MAGNETIC RESONANCE IMAGING (fMRI): A scanner magnetically detects increased blood flow and oxygen metabolism in areas of the brain as the individual processes particular stimuli. The result is a computerized moving picture of activity anywhere in the brain.
ELECTROENCEPHALOGRAM (EEG): Electrodes are taped to the scalp to record the stability and organization of electrical brain-wave activity in the brain's outer laters (cerebral cortex)
POSITRON EMISSION TOMOGRAPHY (PET): After injection or inhalation of a radioactive substance, the individual lies inside a tunnel-shaped apparatus with a scanner that emits fine streams of X-rays, which detect increased blood flow and oxygen metabolism in the brain as the person processes particular stimuli.
NEAR-INFRARED SPECTROSCOPY (NIRS): Thin, flexible optical fivers are attached to the scalp and infrared light is beamed at the brain. Absorption by areas of the cerebral cortex varies with changes in blood flow and oxygen metabolism.
Works well in infancy and early childhood because the child can sit on the parent's lap and move during testing, unlike other methods of measuring brain functioning.
Development of the Cerebral Cortex: largest, most complex brain structure, accounting for 85% of the brain's weight and containing most of the greatest number of neurons and synapses. Brain is most plastic during the first few years than at any later time in life.
PREFRONTAL CORTEX: cortical region that is responsible for thought, including consciousness, memory, reasoning, and problem solving.
BRAIN PLASTICITY: many areas of the brain are not yet committed to specific functioning, so there is a high capacity for learning. If a part of the cortex is damaged, other parts can take over the tasks it would have handled.
Everything we know about brain plasticity comes from research on brain-damaged children and adults
Age matters: brain injury in early childhood causes fewer impairments than adults with later-occurring injuries
At older ages, specialized brain structures are in place, but after injury that can still reorganize to some degree as brain still forms some new neurons, as person practices new tasks it strengthens existing synapses and generates new ones.
Recovery after early brain injury is greater for language than for spatial skills
Impact of brain injury on language: delays persist until 3.5 years of age. Damage to either hemisphere affected early language competence - largely distributed in brain. Catch up means that undamaged areas had taken over language functions.
Impact of brain injury on spatial skills: More impaired. Right hemisphere damage = trouble representing overall shape, left hemisphere damage = omitted details. Spatial skills are more lateralized, and therefore more susceptible to damage.
LATERALIZATION: splitting of cognitive functions between two hemispheres, permits a wider array of functions to be carried out effectively than in both sides processed information in exactly the same way.
Functions associated with the left hemisphere: spoken language, written language, joy
Functions associated with the right hemisphere: anger, reading maps, recognizing geometric shapes
Sensitive Periods in Brain Development: damage can be overcome by good parenting
Extreme deprivation results in permanent brain damage
ORPHANAGE STUDIES: Cognitive catchup happens for kids adopted for 6 months old. Prolonged institutionalization leads to reduction in brainwave and cortical metabolic activity. Disrupts brain's capacity to manage stress, and also disrupts brain's typical response to pleasurable social experiences.
EXPERIENCE-DEPENDENT GROWTH: Occurs throughout our lives. Additional growth and refinement of established structures as a result of specific learning experiences that vary a lot between individuals and culture.
EXPERIENCE-EXPECTANT GROWTH: Refers to brain's rapidly developing organization which depends on ordinary experiences to develop (opportunities to see and touch objects, hear language and sounds, to move and explore)
Changing States of Arousal: Newborns sleep from 16-18 hours per day, this total sleep time decreases slowly, average 2 year old sleeps 12-13 hours per day. Hormone that promotes drowsiness is called MELATONIN.
Influences on Early Physical Growth
When diet and health are OK, growth rate is largely inherited.
If conditions improve, as long as the negative environmental influences were not too severe, babies are likely to show catch-up growth
Benefits of breast milk
Helps ensure healthy physical growth
Protects against many diseases
Ensures nutritional completeness
Protects against faulty jaw development and tooth decay
Provides correct balances of fat and protein
Smooths the transition to solid foods
How does BF help poor mothers and babies?
Free (cheaper than formula)
Tends to increase spacing between siblings
Rapid weight gain is related to obesity at older ages
Preventing infants and toddlers from becoming overweight at older ages
Breastfeed for 6 months; associated with slower weight gain over time
Avoid giving babies food loaded with sugar, salt and saturated fats
Provide lots of opportunity for energetic play
Decrease TV and screen time
Usually appears in the first year of life, caused by a diet low in all essential nutrients, causes the body to become painfully thin
Caused by an unbalanced diet very low in protein, causes a swollen abdomen, usually strikes after weaning
Consequences of extreme malnurition
Children have basal metabolism rate, permanent loss in brain weight, difficulty paying attention
Uncertain access to enough food for a healthy, active life; happens most in single parent families and low-income ethic minority families
Signs of growth faltering: infants whose weight, height and head circumference are substantially below age-related growth norms and who are withdrawn and apathetic. 50% of cases are caused by a disturbed parent-infant relationship.
Family circumstances that often surround growth faltering: unhappy marriage, parental psychological disturbance, irritable or poorly feeding baby (disrupted growth and anxious parents), poverty
Learning = changes in behavior as the result of experience
Infants act (operate) on their environment and stimuli that follow their behavior change the probability that it will occur again.
PUNISHMENT: Removing a desirable stimulus or presenting an unpleasant one to decrease the occurrence of a response.
REINFORCER: A stimulus that increases the occurrence of a response
Contributes to the formation of social relationships...baby looks at adult, adult looks and smiles back,. Their behavior reinforces each other to interact pleasurably with each other.
A neutral stimulus is paired with a stimulus that leads to a reflexive response.
Helps infants to recognize which events usually occur together in the everyday world, so they can anticipate what is about to happen next.
CONDITIONED STIMULUS (CS): A neutral stimulus that leads to a new response once learning has occured.
UNCONDITIONED RESPONSE (UCR): A reflexive response
CONDITIONED RESPONSE (CR): A learned response exhibited toward a previously neutral stimulus.
UNCONDITIONED STIMULUS (UCS): a stimulus that automatically leads to a reflexive response.
EXTINCTION: If the CS is presented alone enough times, without being paired with the UCS, the CR will no longer occur
Fear responses are difficult to evoke in babies because they do not have the motor skills to escape unpleasant events, they have no biological need to form a fear association.
RECOVERY = a new stimulus (change in environment) causes responsiveness to return to a high level
HABITUATION = a gradual reduction in the strength of a response due to repetitive stimulation
As infants get older, they habituate more quickly which shows that they promote information more efficiently.
Imitation = copying the behavior of another person
Imitation contributes to early learning as infants actively try to match body movements that they see with ones they feel themselves make.
MIRROR NEURONS fire identically when a primate hears or sees an action and when it carries out the action on its own.
Fine Motor Development: movements of hands, like reaching, grasping, scribbling with crayons
ULNAR GRASP: A clumsy motion in which the fingers close against the palm
PINCER GRASP: a well-coordinate movement in which infants use the thumb and index finger opposably
PREREACHING: poorly coordinated swipes or swings toward an object
Reaching is controlled by proprioception (sense of movement and location in space) so when eyes are able to fix an appropriate distance, then infants gain greater control of body posture, arm and hand movements.
Gross Motor Development: refers to control over actions that help infants get around in the environment, like crawling, sitting upright and walking
DYNAMIC SYSTEMS THEORY OF MOTOR DEVELOPMENT: when motor skills work as a system, separate motor skills blend together, each cooperating with others to produce more effective ways of exploring and controlling the environment. Motivated by exploration and the desire to master new tasks.
Microgenetic studies show that the order that motor skills develop depend on the anatomy of the body part being used, the surrounding environment and the baby's efforts.
Factors that contribute to development of new motor skills
Body's movement capactiies
Goals that the child has in mind
Central nervous system development
Environmental supports for the skill
Cultural Variations in Motor Development
If babies lie on their backs too much, they show delays in gross motor milestones of rolling, sitting and crawling.
Some cultures (Japanese) discourage motor progress because they think it is dangerous to move before you know enough to keep away from potentially dangerous things.
Bowel and Bladder Control
Recommended that toilet training begin around a child's 2nd birthday because children need to be able to consistently identify signals from a full bladder/rectum and wait for the right place to open their muscles.
Effective toilet training techniques: 1. establishing regular toileting routines, 2. using gentle encouragement, 3. praising children for their efforts
Greatest change in hearing that takes place over the first year of life
Changes in auditory perception over the first year of life that prepare infants for language acquisition
6-8 months: Start to screen out sounds not used in their language, can distinguish musical tunes on the basis of variations in rhythmic patterns (beat structures, accent structure)
7-9 months: Can recognize the same melody when it is plated in different keys....they can make comparable discriminations in human speech. Start to divide awareness from syllables to word like units
Around 5 months: Become sensitive to syllable patterns in their own language. Begin to display a sense of musical phrasing so they prefer music with pauses between phrases rather than awkward phrasing
Familiar speech: At first, babies are sensitive to all sounds but they narrow their focus limiting distinctions they make to the language they hear and will soon learn.
Familiar faces: Originally babies like to look at novel faces, but shortly show no novelty preference.
DEPTH PERCEPTION: the ability to judge the distance of objects from one another and from ourselves. Important for understanding the layout of the environment and for guiding motor activity.
VISUAL CLIFF: Plexiglass covered table with a platform at the center, a "shallow" side with a checkerboard pattern under the glass and a deep side with a checkerboard pattern.
The ability to crawl and the avoidance of the drop offs are linked - LESSON....motor activity helps with cognition.
BINOCULAR DEPTH CUES - we blend 2 visual fields in brain, resulting in depth perception. Use this to adjust hand/arm movements to match object distance.
PICTORIAL DEPTH CUES - artists use these to make pictures 3D. Examples: perspective, overlapping objects, height in picture (to make things look farther away) and shadow.
MOTION - helps babies figure out that objects are not flat but are 3D.
Crawling promotes sensitivity to depth information - as babies learn how to avoid falling in different postures and positions, their understanding of depth expands which promotes new levels of organization of space.
CONTRAST SENSITIVITY: if infants can detect a difference in contrast between two or more patterns, they will prefer the one with more contrast.
Face Perception over the first year of life
2-4 months: Preferences to increasingly complex/detailed, make fine distinctions among features of different faces
5-12 months: able to perceive emotion in faces.
Birth to 1 month: Prefer female, same race and attractive faces. Focus on outer features. Cannot discriminate differences.
Infants with severe visual impairments - typically show delays in motor, cognitive and social development.
Reach motor milestones later
Adults may not provide them with rich exploratory opportunities....they understand relatively late that there is a world of interesting objects to explore
They have to rely on sound to identify where an object is, but sound does not function as a precise way to locate objects until middle of 1st year.
Impacts caregiver-infant relationship
Typically have difficulty evoking caregiver interaction (babies do not make eye contact, imitate or pick up nonverbal social cues); emotional expressions are muted and delated in establishing a shared focus of attention. Typically receive little adult attention and other stimulation vital for all aspects of development.