Anthropology 1025F/G Lecture Notes - Umbilical Cord, Testis Determining Factor, Gestalt Psychology

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Published on 23 Sep 2012
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Development Over The Lifespan- Chapter 12
Developmental Psychology: Issues And Methods
Developmental psychology examines changes in our biological, physical, psychological, and
behavioral processes as we age. Four broad issues guide developmental research:
1. Nature And Nurture- to what extent is our development the product of heredity (nature)
or the product of environment (nurture)? How do nature and nurture interact?
2. Critical And Sensitive Periods- Are some experiences especially important at particular
ages? A critical period is an age range in which certain experiences must occur for
development to proceed normally or along a certain path. A SENSITIVE PERIOD- is an
optimal age range for certain experiences, but if those experiences occur at another time,
normal development will still be possible.
3. Community Versus Discontinuity- Is development continuous and gradual, as when a
sapling slow grows into a tree? Or is it discontinuous progressing through qualitatively
distinct stages, as when a creeping caterpillar emerges from its cocoon as a soaring
butterfly
4. Stability Versus Change- Do our characteristics remain consistent as we changes.
*******Check out the graph on page 440***********
The following are the types of changes:
o No change- an ability present at or before birth that remains relatively constant across the
lifespan (ex. The ability to discriminate high from low pitched sounds , or to see objects
as distinct from their background: figure ground perception)
o Continuous change (continuity)- an ability not present, or very immature, at birth that
develops gradually over months or years and then remains constant over age (certain
types of intelligence)
o Stages (discontinuity)- an ability that progresses in stages, with relatively rapid shifts
from a lower level of performance to a higher level (eg. In motor development, the shift
from rolling to crawling, to standing, to walking, in cognitive development, the shift from
non- verbal thought to symbolic thinking involving words.)
o Inverted U shape function- an ability that emerges after birth, peaks and disappears with
age. (eg. Separation anxiety, visual activity across the lifespan)
o U- shaped function- an ability that is present early in life disappears temporarily and re-
emerges later (eg. Newborn turning point toward off centered sound and stepping with
support
To study how intellectual abilities change from age 10- 600 uses a CROSS- SECTIONAL
DESIGN- we would compare people of different ages at the same point in time. We would test
each person only once and compare how well the different age groups perform. This is widely
used because data for many age groups can be collected relatively quickly, but a key drawback is
that the different age groups called COHORTS grew up in different historical periods. This would
trickle down to seeing the environmental differences
To avoid this problem, a LONGITUDINAL DESIGN repeatedly tests the same cohort, as it grows
older. So, you track them and test the every ten years for example until they turn 70, to make sure
that everyone is exposed to the same historical time frame. The downside is that it is time
consuming, and as years pass, sample may shrink substantially as people move, drop out of the
study, or die. If we find intelligence decline at age 60, is it really due to aging or developmental
experiences unique to a particular cohort? Researchers can answer this using SEQUENTIAL
DESIGN- that combines the cross sectional and longitudinal approaches. That is we can
repeatedly test several age cohorts as they grow older and determine whether they follow a similar
developmental pattern. This design is the most comprehensive, but also the most time consuming
and costly
Prenatal Development
Consists of 3 stages of physical growth:
o The germinal stage- constitutes approximately the first two weeks of development,
beginning when one sperm fertilizes a female egg (ovum) this fertilized egg is called a
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zygote. Through repeated cell division the zygote becomes a mass of cells that attaches to
the mothers uterus about 10- 14 days after conception
o The embryonic stage extends from the end of the second week through the eighth week
after conception, and the cell mass is now called an embryo. Two life- support structures,
the placenta and umbilical cord, develop at the start of this stage. Located on the uterine
wall, the placenta contains membranes that allow nutrients to pass from the mother‘s
blood to the umbilical cord. In turn, the umbilical cord contains blood vessels that carry
these nutrients and oxygen to the embryo to the mother. Supplied with nutrients,
embryonic cells divide rapidly and become specialized. Bodily organs and systems begin
to form and by week eight the heart of the embryo is beating. The brain is forming, and
facial features such as eyes can be recognized. At 9th week embryo is called a fetus.
During the fetal stage, which lasts until birth, muscles become stronger and other bodily
systems continue to develop. At 24 weeks, eyes open, 28 weeks fetus attains the age of
viability, meaning that it is likely to survive outside the womb in case of premature birth
Genetics And Sex Determination
Female and male both have 23 chromosomes each. At conception, contains 23 pairs. The 23rd pair
of chromosome determines the baby‘s sex. A genetic female‘s 23rd pair contains 2 X
chromosomes (XX), so called because of their shape. Because women carry only X chromosomes,
the 23rd chromosome in the egg is always an X
A genetic males 23rd pair contains an X and Y (XY)
The Y chromosome contains a specific gene known as the TDF (Testis determining factor) that
triggers male sexual development.
At 6- 8 weeks after conception the TDF gene initiates the development of testes, once formed, the
testes secrete sex hormones called ANDROGENS that continue to direct a male pattern of organ
development. If TDF is not present testes do not form. In the absence of sufficient androgen
activity during this prenatal critical period- an inherent pattern of female organs develop
Environmental Influences
Teratogens- are environmental agents that cause abnormal prenatal development
Fetal Alcohol Syndrome (FAS)- is a group of severe abnormalities and small malformed brain.
Psychological symptoms of FAS my include IQ and fine and gross motor impairments and poor
adaptive functioning
Loud sounds elicitae reliable increase in fetal heart rate and boy movement during the 3rd trimester
of pregnancy
Nature and nurture play a role in pregnancy. When pregnant the womb can remember and
recognize sounds and words.
Newborn Sensation And Perception
Robert Fantz used PREFERENTIAL LOOKING PROCEDURE to study infants‘ visual
preferences
Newborns orient to significant stimuli in their environment, the most important being their
mother‘s face, voice and smell, optimizing their access to food, warmth and social stimulation
Newborn Learning
Learn rapidly when born, recognize familiar stimuli, and stare at mother
VISUAL HABITUATION PROCEDURE- the same stimulus is presented repeatedly until infant
looking time declines.
When a novel stimulus is presented, infants usually look longer at the novel rather than the
familiar stimuli.
Russel Adams and Mary Courage used VHP to study newborn color vision
Philip Zelazo used an AUDITORY HABITUATION PROCEDURE to study infant memory
Barbera Morrongeillo used habituation procedure and showed that newborns rapidly learn
particular sounds with particular objects including mother‘s face and voice
Newborns can learn through classical and operant conditioning and imitation
Infants are born with mechanisms that help them respond to caretakers and important events in the
environment
Sensory- Perceptual Development
Visual field in each eye expands to almost adult size in 6 months
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Around 3- 4 months of age, infant pattern perception is organized according to certain Gestalt
principles
Not all perceptual developmental functions show improvement with age during infancy
Developmental function from 20/800 at birth to 20/ 100 by 6 months of age.
Around 3 to 4 months of age, infant pattern perception is organized according to certain Gestalt
principles, while other Gestalt principles appear in step like fashion.
Not all perceptual development functions show improvement with age during infancy
Phonemes- sound difference in words
Sensory perceptual processes are exercised in the uterus, and the al, including vision, operate at
some level at birth
Physical Brain And Motor Development
Maturation- the genetically programmed biological process that governs our growth, our bodies
and movment (motor) skills develop rapidly during infancy and childhood
o Cephalocaudal Priciple- reflects the tendency for development to proceed in a head to
foot direction
o Head and fetus is proportionately larger
o Proximodistal Principle- states development begins along the innermost parts of the body
and continues towards the outermost parts of the body and continues toward the
outermost parts. Thus a fetus‘s arms develop before the hands and fingers and at birth
infants can control their shoulders but not their arms or hand muscles.
The Young Brain
At birth-brain is far from mature, and has reached only about 25% of its eventual adult weight
By 6 months- the brain reaches 50%
Neural networks that form the basis for cognitive and motor skills develop rapidly
The first brain area to mature fully lie deep within the brain and regulate basic survival functions
such as heartbeat and breathing
Last areas to mature re the frontal cortex which is vital to our highest level cognitive function
Cortex matures around age 5, where 90% of growth is reached and the cerebral hemispheres
become more highly specialized
Motor Development
Follows a regular stagelike sequence
Reflexes- defined as automatic ―inborn‖ behavior elicitated by specific stimuli- present at birth
such as breathing, the rooting reflex and sucking
Healthy reflexes indicate normal neurological maturity at birth
Environmental And Cultural Influences
Malnutrition stunts general growth and brain development but also is a major source of infant
death
Physical growth and perceptual motor development reinforce 3 points that apply across the realm
of human development:
o Biology sets limits on environmental influences
o Environmental influences can be powerful
o Biological and environmental factors interact
Piaget’s Stage Model
Came to believe that the key issue in understanding how children think was not whether they got
the right answers, but how they arrived at their answers
Relied on observational research
Proposed that children‘s thinking changes QUALITTIVELY with age.
Believed cognitive development results form an interplay of maturation and experience, and he
viewed children as natural born scientists who actively explore and seek to understand their world.
To achieve this understanding the brain builds schemas (or schemata) which are organized
patterns of thought and action
Cognitive development occurs as we acquire new schemas, and as our existing schemas become
more complex. According to Paiget, 2 key processes are involved:
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