Refers to a person's genetic make up;
Refers to observable characteristics, which are due to a combination of genetic and environmental factors
Bronfenbrenner's Ecological Model
Described development as involving interactions btwn the indiv. & his/her context or environment.
This model distinguishes btwn 5 environmental systems or levels:
- Microsystem: The childs immediate env. & includes face-to-face rel. w/home, school & neighborhood.
- Mesosystem: Consists of interactions btwn the components of thr micorosystem (e.g., parents involvement in childs school exp. & interactions btwn the childs church & community).
- Exosystem: Consists of elements in the broader env. that affect the childs immediate env. & social setting that indirectly affect the childs devel. (e.g, the parents job, school board, media, local industry, comminity agency).
- Macrosystem: Includes the cultural beliefs, & practices, economic conditions, politics, values, laws, customs, etc. of the childs culture.
- Chronosystem: Consists of env. events that occur over an indiv lifespan & impact the indiv. in ways that depend on the indiv. circumstances & devel. stage.
Argued that the greater the number of risk factors a baby is exposed to, the greater the risk for negative outcomes. He concluded that the following 6 family risk factors are particularly accurate predictors of child psychopathology:
- Severe marital discord (Greatest risk factors)
- Low SES,
- Overcrowding or large family size,
- Parental criminality,
- Maternal psychopathology,
- The placement of a child outside the home/Foster care
Resilience (Werner and Smith)
Longitudinal research found that exposure to early (prenatal & perinatal) stress may be reduced when the baby:
- experiences fewer stressors following birth,
- exhibits good communication skills & social responsiveness, and
- receives stable support from a parent or other caregiver
Critical and Sensitive Periods
Critical period is a time during which an organism is especially susceptible to positive & negative environmental influences.
Sensitive period is more flexible than a critical period and is not limited to a specific chronological age.
Some aspects of human development may depend on critical periods, but,
for many human characteristics & behaviors, sensitive periods are probably more applicable.
3 stages of prenatal development:
- Germinal Stage: (Fertilized ovum = zygote) in 1st 2 weeks.
- Embryonic Stage: Begining of 3rd week to 8th week.
- Fetal Stage: Begins at onset of 9th week & goes till birth.
Birth defects are caused by chromosomal D/O's, exposure to tetatrogens & poor maternal health.
When a D/O is carried on an autosome (22 pairs of chromosomes). All human cells (except sperm & ovum) contain 46 chromosomes arranged in 23 pairs.
- 22 pairs are autosomes
- 23rd pair contains the sex chromosomes
- Females = XX
- Males = XY
Sex Linked Disorders
When a D/O is carried on sex chromosomes
Ex: Klienfelter Syndrome & Turner Syndrome
Disorders due to Dominant & Recessive Genes
Disorders related to chromosomes are the result of inheritance of a single dominant or 2 recessive genes or a chromosomal abnormality.
Dominant Gene D/O's: Due to the inheritance of a single dominant gene from 1 parent.
- Huntington's Disease: An autosomal dominant gene disorder bc the gene responsible is located on an autosome.
Recessive Gene D/O's: Due to inheritance of a pair of recessive gene's; 1 from each parent.
- Cystic Fibrosis
Autosomal recessive condition (Homozygous, 2 recessive genes); 1 recessive gene from each parent.
Caused by a pair of recessive genes & produces mental retardation unless the infant is placed on a diet low in phenylalanine soon after birth.
Phenylalanine an amino acid found in milk, eggs , bread can cause MR unless the infant is put on a special diet soon after birth.
Caused by an extra number of 21 chromosome.
It is characterized by mental retardation, retarded physical growth & motor development, distinctive physical characteristics, & increased susceptibility to Alzheimer's dementia, leukemia, and heart defects.
Occurs in males & is due to the presence of 2 or more X chromosomes along with a single Y chromosome (due to an abnormal level of sex chromosomes).
Males with this disorder have:
- A small penis & testes,
- Long legs & short trunk
- Develops breasts during puberty,
- Has limited interest in sexual activity,
- Often sterile, and
- May have learning disabilities & behavior problems
Occurs in females when 1 X chromosome is missing or incomplete (due to abnorm # of sex chromosomes).
- Short stature
- Drooping Eyelids
- Webbed neck & other physical features
- Retarted/absent devel. of secondary sex charaterisitcs.
- May have hearing & vision problems & a learning disability
Caused by a chromosomal deletion on the paternal side & includes:
- Some degree of MR
- May exhibit OCD behaviors
Env. agents that adversely affect prenatal devel. & cause birth defects in the developing fetus & include:
- Alcohol: 2nd half of 1st trimester = Severe structural physical abnormalities. 2nd & 3rd trimester = Assoc w/ behavioral & psychological deficits
- Env. Hazards
- Certain maternal conditions
Exposure during 3-8 weeks (embryonic period) most likely to cause major structural abnormalities.
Prenatal Exposure to Alcohol during 1st Tirmester
Exposure during the 1st Trimester likely to produce severe physical defects.
Res. shows that alcohol exposure during the 2nd half of the 1at Trimester is assoc. w/ most severe physical defects:
- Low birth weight
- Smaller-than-normal head circumference
- Altered shape of eyes & lips
Prenatal Exposure to Alcohol during 3rd Tirmester
In the 3rd Trimester alcohol exposure can impact development of attention & other cognitive Fx's
Fetal Alcohol Syndrome/Effects
Prenatal exposure to alcohol can produce a variety of physical, behavioral, & cognitive Sx's that, in terms of severity, depend on the amount of alcohol consumed by the pregnant woman.
- Fetal Alcohol Syndrome (FAS): Characterized by facial deformities, mental retardation, growth retardation, motor impairments, physical defects, CNS dysfx, LD's and behavioral problems.
- Fetal Alcohol Effects (FAE): are less severe and usually do not include facial deformities and mental retardation.
- The symptoms of both disorder are largely irreversible.
- Negative impact on the basal ganglia, hippocampus, frontal lobes, cerebellum, hypothalamus, corpus callosum
If Mom HIV+ the chances of transmitting it to her child is 35-60%, the risk is greatly reduced when she takes an anti-retroviral drug during pregnancy & delivery.
A minority of babies birn w/HIV devel. severe Sx's in 1st month after birth, while the rest have a later appearance & slow progression of Sx's
With Tx infants can survive to 8yrs and beyond
Infected children have delays in physical & cog. devel. & high rates of life-threatening opportunistic infections
Prenatal Exposure to Cocaine
Use of cocaine by a pregnant woman increases the risk for spontaneous abortion & stillbirth.
Infants born to cocaine users are at high risk for:
- low birthweight, and
- reduced head circumference,
- often exhibit tremors,
- Difficult to soothe
- an exaggerated startle response; highly reactive
- a high-pitched cry, sleep and feeding difficulties, and
- developmental delays
- During the early school years these children have higher than norm rates of LD's & behavior probs.
Malnutrition During Prenatal Development
Malnutrition during prenatal devel. is associated with:
- stillbirth, and
- low birth weight and
- may result in suppression of the immune system,
- Cog. deficits
- Weak immune system
- mental retardation, and
- Defects in structure of liver, pancrease & other organs
- other serious problems.
Severe malnutrition in the 3rd trimester (especially protein deficiency) is particularly detrimental for the developing brain & can lead to a reduced number of neurons, reduced myelinization, & neurotransmitter abnormalities.
Good nutrition after birth can reduce some of the negative effects
Congenital Cytomegalovirus (CMV)
Type of herpes virus, infection during adulthood produces no or mild Sx's, but infection during prenatal devel./birth can be life-threatening.
2nd most common cause of Mental Retardation after Down Syndrome & likely to cause cognitive impairments in hearing & Vision.
Approx. 10% of infants infected w/CMV show Sx's at birth & about 10-15% of infants who are asymptomatic at birth devel. Sx's during 1sr few yrs of life.
Brain Development (Cerebral Cortex)
The cerebral cortex is largely undeveloped & least devel. part of brain at birth (25% of adult weight) but shows dramatic growth during the first 2 years of life (approx 80%) as the result of:
- an increase in the size of existing neurons,
- more extensive dendritic branching,& increasing myelinization.
Cerebral Cortex responsible for higher level cog. Fx, language, spatial skills & complex motor activities.
The frontal lobes continue to mature into adolescence and the early 20s.
Some neurogenesis (regeneration) occurs in adulthood, especially in hippocampus & brain also compensates for loss of neurons thru axon sprouting, dendrite branching & creation of new synapses
30 yrs of age the brain gradually starts to shrink as a result of loss of neurons & acceleration of brain loss after 60 yrs old in sensory & motor cortex.
Reflexes are unlearned responses to particular stimuli in the environment.
Early reflexes include:
- Babinksi reflex (toes fan out & upward when soles of the feet are tickled)
- Moro reflex (flings arms & legs outward & then toward the body in response to a loud noise or sudden loss of physical support)
- Rooting (Turn head in direction of touch applied to the cheek)
- Stepping: (Makes coordinated walking movements when held upright w/feet touching flat surface)
Produced by tickling the middle of the sole of the infants feet.
Flings arms & legs outward & then toward the body in response to a loud noise or sudden loss of physical support (being dropped).
Turn head in direction of touch applied to the cheek
Perception in Newborns (Vision, Audition, Pain)
Of the senses:
Vision: The least well developed at birth.
- At birth, the newborn sees at 20 feet what normal adults see at about 200-400 feet; w/in 2-5 days after birth infants pref. to look at human faces vs other objects.
- 1-2 mos. Prefer/can distinguish faces of mother over face of unfamiliar woman
- 1-6 mos. some degree of Depth Perception.
- About 6 months, the infant's visual acuity is probably very close to that of a normal adult.
- Visual Stimuli: Newborns prefer to look at high-contrast patterns (e.g. a bold black-and-white checkerboard), and their preferences for more complex patterns increases with increasing age.
- Babies have some color vision by 2-3 months of age (red, green, blue & yellow)
Audition: Fetuses hear sounds in utero during the last months of devel.
- Newborns only slightly less sensitive to sound intensity than adults & soon after birth can distinguish the voices of the mother from a stranger.
- Auditory Localization: Ability to orient toward the direction of the sound is evident shortly after birth, but then disappears btwn 2-4 mos. & re-appears & improves rest of 1st yr.
- Can distinguish btwn different vowel sounds w/in a few days after birth.
- 2-3 mos. can distinguish btwn different consonant sounds
Pain: The research has confirmed that newborns are sensitive to pain.
- Ex: Male newborns who are circumcised without anesthesia often react w/a loud cry, a facial grimace, & an increase in heart rate, blood pressure, &muscle tension.
- There is evidence that exposure to severe pain as a newborn can impact later reactions (e.g., in some cases, can increase sensitivity to pain).
Visual Cues Infants use to percieve depth arise in a predictable sequence. Which is the last to develop?
Depth perception depends on devel. a sensitivity to 3 types of cues:
- Kinetic (Motion) Cues (1-3 mos)
- Binocular Cues (2-4 mos)
- Pictoral Cues (5 mos): Last to devel. & includes size, texture & shading.