Psychology 001
Introduction to Psychology
Christopher Gade, PhD
Office: 621 Heafey
Office hours: F 3-6 and by apt.
Email: gadecj@gmail.com
Class WF 7:00-8:30 Heafey 650
Today’s Lecture is on
Developmental Psychology!

What do
developmental
psychologists study?

Development and
Change
Cognitive
 Personality and
Emotion
 Physical


Genetics
Genetics and Development

Why do developmental psychologists study
genetics?

Attempt to determine heritability
Heritability: an estimate of the variance within a
population that is due to heredity.
 Note: This a chance for us to revisit the nature versus
nurture issue.



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Nature – the effects of your genetics on aspects of your
development and psyche
Nurture – the effects of the environment on aspects of your
development and psyche
Attempt to identify specific genes and genotypes
Biological Beginnings
At one point in time in each of our pasts,
we were one cell
 These cells contained a very
special code that was transferred
to every cell replicated from this
first cell
 These codes determined a very, very
large portion about who we are today,
who we were in the past, and who we
will be in the future.

More on the “Code”

Your “code” was contained
within the nucleus of these
cells on threadlike structures
called chromosomes


Deoxyribonucleic acid (DNA) – a
complex molecule that contains
genetic information and has a
double helix shape
Genes – units of heredity
information composed of DNA;
Genes direct cells to:
A) reproduce themselves
 B) assemble proteins that direct cell
growth and body processes

Looking Closer at the
Code


Each of our genetic
combinations are located
on strands called
chromosomes. Each
person has 23 pairs of
chromosomes (e.g. 4
chromosomes total).
Most chromosomes in
humans look very similar
under the microscope,
except for one.
What We’ve Learned about Genes


Genes not only determine how your cells are
going to multiply and grow, they determine a
lot about who you are and how you’re going
to develop
We now believe that the average human cell
contains approximately 20,500 genes



Human genome – the complete set of genes
contained within a human being
Note: genes are outnumbered by proteins, this
indicates that the genetic code in these genes
collaborate with each other, and can be turned on
and off due to these collaborations
Computer programming analogy
How do developmental psychologists
study heritability from genes?
- Sibling studies
 Identical (monozygotic) and fraternal (dizygotic)
twins

Siblings (similar to fraternal twins)

Adopted children

Twins reared together compared to twins reared
apart
Minnesota Twin Registry (Thomas Bouchard)
 Sweeden Twin Research

Example of Correlation Results
found in Twins Studies
Jim Lewis
and
Divorced (Linda)
Remarried (Betty)
Middle Class
Romantic/affectionate
Son “James Alan”
Dog “Toy”
Woodshop
Stock car racing
Drinking Miller Lite
Chain Smoker
Chewed nails to the nub
Migraines
Jim Springer
Divorced (Linda)
Remarried (Betty)
Middle Class
Romantic/affectionate
Son “James Alan”
Dog “Toy”
Woodshop
Stock car racing
Drinking Miller Lite
Chain Smoker
Chewed nails to the nub
Migraines
Do these twin studies tell us everything we
need to know about genetic influence?

The influence of genetics on behavior in society

The influence of experience on behavior in
society

The influence of genetics and experience on
society’s reaction to the individual

The influence of society’s reactions on behavior.

The circular pattern that goes on, and on, and
on…
Looking at Development: From a
Single Fused Cell to Birth


Developmental scientists study human
development from the point of conception to
death. However, a large focus of their research
examines the specifics of what occurs up to birth
and immediately after.
From research, we’ve come to believe that our
development from fertilization to birth can be
split up into three different periods:


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Germinal period (0-14 days after conception)
The embryonic period (2-8 weeks after conception)
The fetal period (8 weeks to birth)
The Germinal Period (0-2 weeks)



The fertilized egg is called a zygote in this period
The original cell multiplies rapidly (mitosis) in this
stage (over 100 cells by 1 week)
Two masses of cells already begin to form in this
stage



Blastocysts – inner mass of cells
that will eventually develop into
the embryo
Trophoblasts – outer layer of cells
that later provide nutrients and
support for the cell
Implantation – the attachment of
the zygote to the uterine wall of a
female – marks the end of this stage of development
The Embryonic Period (2-8 weeks)


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After the blastocysts attach to the uterine wall
Cells multiply faster in this period
The cells diversify even further
(organagenesis - organ formation)


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Endoderm – digestive/respiratory systems
Ectoderm – nervous system, sensory receptors
Mesoderm – circulatory, bones, muscles, excretory
and reproductive systems
Life support system


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Amnion - protective envelope that eventually contains
amniotic fluid
Umbilical cord – arteries and vein that connect the baby to
the placenta
Placenta – a group of tissues that intertwine with the
mother and is used for for sharing of small molecules
between the mother and child
Brain
Development
at this Stage

Neural tube, a collection of
cells that will form the brain
and nervous system develop
during this period



Located on the embryo’s back
Forms between 2 to 3 weeks
after conception
Must close or severe birth
defects occur
Ancephaly – highest regions of
the brain fail to develop
 Spina bifida – lower regions of
the neural tube fail to close,
resulting in varying levels of
paralysis

After the Neural Tube Closes
•
Neurogenesis – massive reproduction of the cells in
this tube (become the nervous system)
and
•
Neuronal migration – the moving
and formation of nervous system
structures

Synapses – connection between
neural cells called neurons

video
occur after the neural tube has closed
The Fetal Period – (8 Weeks to Birth)

In addition to the three periods, human growth is
often split into three trimesters, the fetal period
begins in the last 1/3 of the first trimester
The Second Trimester
Point of Possible Survival Outside the
Womb
The Third Trimester
At Birth

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Little to no control over most muscles
Horrible visual abilities
60-100 billion neurons in the brain/nervous system
Apgar scale – identifies ability to handle stress and
high-risk infants
A few reflexes (Rooting, Sucking, Grasping, Babinski,
Stepping)
So What Have We Learned?


We learned about the
relationship between
genetics and
developmental
psychology.
We learned about the
physical development
that takes place as we
transition from an
embryo to a newborn.
Now what?


In the next class, we’ll discuss the
cognitive and social development of
individuals after they are born.
Our main focus for the next section will be
on Jean Piaget and his theories about the
cognitive development of children, but
we’ll extend his work to examine other
developmental theorists as well.