Psychology of Human Development  

What is Correlational Design?

Lecture Notes

Week #2

Research Designs 

1.) Correlational Design- most straightforward, measures two variable to see if  they relate and to see if there is a correlation. A correlation coefficient is used and varies from -1 to 1. If there is no relationship found, then the correlation  coefficient is 0. The sign reflects direction of relationship where as absolute  value reflects degree of relationship/strength.  

Y-Values

6

4

2

0

0 1 2 3 4 5 6 7 8

20 15 10 5

0

Y-Values

0 1 2 3 4 5 6 7 8 Positive correlation

Ex. Negative correlation

*You’re not attempting to change or influence a participant’s performance on either  variable, just measuring to see if there is a relationship

Limitation?

∙ Cannot infer cause and effect relationship

∙ Don’t know which variable is cause and which is effect

What are twins?

∙ Third variable effect- may infer two variables have a casual relationship when there is an actual 3rd variable involved (ex: Pellagra disease. Researchers  found that houses that had indoor housing sewage disposal didn’t have

pellagra disease compared to those who used outhouses. However, the third  variable involved was diet. People who were able to afford high protein and  high-quality food did not obtain the disease. (3rd variable= socioeconomic  status)

Experimental Designs 

∙ Directly manipulate the independent variable, the variable expected to cause changes in the second. IV= exposure to drug DV= prevalence of  disease

∙ Groups must be equal prior to manipulation of IV to infer cause and effect,  typically achieved by random assignment to groups We also discuss several other topics like londoner v denver

Problem? Not always ethical, ex: smoking causes lung cancer, it would be unethical  to put babies in a room full of cigarette smoke to prove this. This is why animals are  often times used for experimental designs because when combined with  correlational experiments we can develop a conclusion.  

What is a Quasi-Experimental design?

Quasi-Experimental design 

∙ Natural situation in which two groups seem to differ only on variable of  interest

∙ Ex: cholera disease, researchers thought that it was spread through  exposure. There were two districts in London that were equally similar except  how they received their water. One received it upstream and one  downstream. Researchers found that upstream had less cholera than  downstream

∙ Can use this design because even though the experiment could be deemed  unethical, its already happening in the world

∙ Also called natural experiment

∙ Cannot be sure that groups differ on no other variables

Developmental Research Designs- Human development

1.) Cross sectional (most widely used)

∙ Different aged groups are tested at same time

∙ Weakness- does not allow on to study changes in an individual, also the  cohort effect (people of different ages were born in different times. May differ  in ways other than age). Ex: A 20-year-old born in 1998 compared to an 85  year old who was born into the Great depression. We also discuss several other topics like uw lsj

2.) Longitudinal design

∙ Each participant is tested at a number of ages, follow the same individuals to  see how they changed over time.

∙ Cohort effect is decreased

∙ Weakness- can require a long time to complete the study. Practice effects  (participants may learn from testing) for example students who take the ACT  and SAT normally score better the second time not because they are smarter  but because they learned HOW to take the test. Participant morality  (participants who drop out may differ from those who remain) this could  effect the statistical data from the study. And finally, results from one cohort  may not generalize. For example, the obesity epidemic. The average body  weight growth charts have changed over the years.  

3.) Sequential design- combination of cross sectional and longitudinal designs

Chapter 2 

Key development issues 

1.) Nature vs Nurture- nature theorists propose that development is driven by a  maturational program contained within one’s DNA whereas nurture theorists  propose that development involves changes in response to environmental  events

2.) Activity vs. Passivity- Passivity theorists propose that development is shaped  by environmental and genetic factors beyond one’s control. Ex: The  behaviorists view point believe you could make a child into anything due to  the environment. Activity theorists propose that people select and shape  their environments in order to influence their own development. Ex: we chose to stay in school longer than we had to in order to better shape our future. We also discuss several other topics like uw classics

3.) Continuity vs Discontinuity- Continuity theorists propose that development  involves gradually expanding the same structures and skills that were  present at birth. Ex: babies can see at birth but develop better eyesight over  time. Discontinuity theorists propose that development involves dramatic  reorganizations in structures or skills. Ex: butterfly cycle from a larvae to a  butterfly.  Don't forget about the age old question of accrural accounting

Stage theory: a series of qualitatively different forms or ways of thinking,  basically means that we possess skills now that were not even possible when  we were young.

4.) Universality vs context-specificity- Universality is when people all go through  the same set of developments and context specificity is the idea that  development can follow different paths depending upon the circumstances of  development

Chapter 3 “Genetics”

Chromosomes: stores genetic information that we obtain from parents. Total of 46 in every cell

DNA- chemical substance that makes up chromosomes and can reproduce through  mitosis

Gene- segment of DNA that codes for a protein, we have about 20,000 genes Genetics and Heredity 

∙ Sperm and egg each have 23 chromosomes

∙ Created through process of meiosis

∙ They combine to form zygote with 23 pairs of chromosomes

Genetic Differences 

∙ Each child receives just one of 2 chromosomes in each pair from each parent  (2^23 possibilities)

∙ Crossing over occurs which is when the ends of a chromosomes switch  positions before assorting into sex cells If you want to learn more check out after some neurotransmitters are released, the neuron takes up most of the neurotransmitter molecules intact and reuses them. this process is called:
Don't forget about the age old question of mcphs bookstore

Twins 

∙ Identical twins- single fertilized egg (zygote) splits in 2 individuals after  conception. They are genetically identical

∙ Fraternal twins- two different eggs fertilized by two different sperm. Therefore they are no more similar than ordinary siblings