RESEARCH
METHODS
Goals of Psychology
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•
•
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Describe
Explain
Predict
Control
…………behavior and mental processes
Critical Thinking
• Thinking that does not blindly accept
arguments or conclusions but
questions their validity
• NOT parsimonious thinking
(willingly accepting the most simple
explanation).
Scientific Method
• Technique using tools such as
observation, experimentation, and
statistical analysis to learn about the
world
• Through its use, psychology is
thereby considered a science.
Steps to the Scientific Method
• Form a testable question
• Develop a hypothesis
• Test Hypothesis - Design study to collect data
– Experimental
– Descriptive
• Analyze data
– Use of statistical procedures
– Use of meta-analysis
• Draw a conclusion
• Report results
– Publication
– Replication
Things That Make Us WRONG:
Why we need the scientific method
Common Sense
• Conclusions based solely on personal
experience and sensible logic
• Most of the time it is good but…
• Can lead to incorrect conclusions
What are the Odds of Each?
What are the Odds of Each?
1 in 2,598,960
What are the Odds of Each?
1 in 2,598,960
1 in 2,598,960
Did you know…
• It is nearly impossible to fold a regular
sheet of paper in half more than 7 times.
• Go ahead and try!
• Mythbusters pulled it off with a piece of
paper as big as an airplane hanger and a
steam roller.
Science vs. Common Sense
• Science helps build explanations that are
consistent and predictive as opposed to
conflicting and describing the past
(hindsight)
• Science is based on
–
–
–
–
knowledge of facts
developing theories
testing hypotheses
public and repeatable procedures
Bias
• Situation in which a factor unfairly
influences the likelihood of a
particular conclusion
• Bias should be minimized as much as
possible in research
Hindsight Bias
• The tendency to exaggerate one’s ability to have foreseen
how something would turn out after learning the outcome.
• The “I knew it all along” phenomenon.
– Week before the 1985 Super Bowl, 81% of Dr. Brigham’s students
predicted the Miami Dolphins would win. 40% said the Dolphins
would win by 10 or more points.
– A week after San Francisco 49ers decisive victory, he asked the
group who picked the 49ers.
• 58% said they picked the 49ers
• NO ONE remembered saying the Dolphins would win by at least
10 points.
Overconfidence
• Tendency to overestimate the accuracy of
our current knowledge
• We are more confident than we are correct.
• How many of you overestimated the
number of correct answers on your
True/False Quiz?
Confirmation Bias
• Our tendency to search for information that
confirms our beliefs and ignore those that don’t.
• Try this card trick:
http://www.caveofmagic.com/results1.htm
• This works because we only look for our chosen
card confirming Simeon’s mental telepathy and
ignore the fact that second set of cards is in fact,
an entirely new set!
• NONE of the cards in the new set is the same as
the old one so of course the card you picked is
missing.
Researcher Bias
• The tendency to notice evidence
which supports one particular point of
view or hypothesis
Volunteer Bias
• People who volunteer to participate in a survey
differ from those who do not.
• Those who complete it are often willing to share,
have similar interests, have spare time (magazine
surveys).
• These factors skew or slant the results.
• Eliminate this by using a random sample where
everyone has equal chance of being chosen to
participate.
Participant Bias
• Tendency of research subjects to respond in
certain ways because they know they are being
observed
• The subjects might try to behave in ways they
believe the researcher wants them to behave
• Can be reduced by naturalistic observation
Eliminating Bias
• “Placebo Effect” – participants react because they
THINK they are receiving treatment (sugar pill)
– Mind over Matter
• “Nocebo” – If told a drug won’t work, the person
will feel it doesn’t work even if it is a legitimate
drug.
• Single Blind Study – participants do not know if
they are getting the treatment or not
• Double Blind Study – neither the researcher or
the participants know if they are getting the
treatment or not
Research Strategies Fall Into 2
Categories
• Descriptive—strategies for observing and
describing behavior
– Observation
– Surveys
• Experimental—strategies for inferring
cause and effect relationships among
variables
Longitudinal Study
• Researchers study the same group of
individuals for many years to see how
they change.
• Can be very expensive and difficult to
conduct
• Risky – people may drop out
• Ex: Ruby Payne studied poverty
Cross-Sectional Study
• Researchers simultaneously study a
number of subjects from different age
groups and then compare the results to see
how they are different.
• Cheaper, easier than longitudinal studies,
but group differences may be due to
factors other than development. (More
variables.)
Longitudinal/Cross Sectional
Study
Naturalistic Observation
• Method of observation where subjects are
observed in their “natural” environment
• Subjects are not aware they are being
watched – researcher does not interfere
• Could use hidden cameras or two way
mirrors
• Ex: People eating in a restaurant
Laboratory Observation
• Not always a sterile room.
• Place where the environment can be controlled
to minimize the number of variables.
• Negatives are that it may cause the subject to
act differently than it normally would.
• Ex: Skinner Box, maze, fish tank
Case Study
• In depth study of one individual with the hopes of
determining universal principles
• Generally used to investigate rare, unusual, or
extreme conditions
– Example: Phineas Gage
Negatives:
• This technique is very open to bias
• Difficulty of applying data from one person to
everyone
Survey Method
• Research method that relies on selfreports; uses surveys, questionnaires,
interviews.
• Usually a very efficient and inexpensive
method; able to get a large sample
• Can you guess some limitations of this
method of research?
Survey Limitations
• Accuracy is a concern; people are not always
honest.
• They fear confidentiality or want to please the
researcher.
• Example: Tooth brushing survey in 1960s. If as
many people actually brushed their teeth as often
as they claimed to brush their teeth, 33% (?) more
toothpaste would have been sold that year.
Sampling Terms
• (Target) Population—large (potentially infinite)
group represented by the sample. Findings are
generalized to this group.
• Sample—selected segment of the population for
the study
• Stratified or Representative sample—closely
parallels the target population on relevant
characteristics; sample is proportional to
TARGET POPULATION
• Random selection—every member of larger
group has equal chance of being selected for the
study sample
Random Sample
• A sample that represents the target
population:
– Each member of the population has an equal
chance of being included.
– If a sample is not random it is said to be
biased.
– Increase chances of representing population
when sample is BIG ENOUGH
– How would you pick a random sample???
Generalizing the Results
• Applying the findings from the research
group to other groups.
• Be cautious about generalizing when it isn’t
a random or stratified sample.
• Example: Car preference differs between
men, women, region, socio-economic
background, and more.
Correlational Study
• Correlations examine relationships between
categories of facts.
• Correlation reveals relationships among facts
– e.g., more democratic parents have children who behave better
• A correlational study does NOT determine HOW
the two variables are related – just that they are
related
• Correlational studies are helpful in making
predictions.
Correlational Study
• Correlation CANNOT prove causation
– Do democratic parents produce better behaved children?
– Do better behaved children encourage parents to be
democratic?
• May be an unmeasured common factor
– e.g., good neighborhoods produce democratic adults and
well-behaved children
• Does NOT determine why the two variables are
related--just that they are related.
Correlation & Causation
• There is a strong +.90 correlation in shoe
size and IQ.
• Does this mean that a large shoe size is the
cause for higher intelligence?
• What else could explain this?
•YOUR FEET GROW
AS YOU GET OLDER &
WISER
Positive Correlation
• As the value of one variable increases
(or decreases) so does the value of the
other variable.
• A perfect positive correlation is +1.0.
• The closer the correlation is to +1.0,
the stronger the relationship.
Negative Correlation
• As the value of one variable
increases, the value of the other
variable decreases.
• A perfect negative correlation is -1.0.
• The closer the correlation is to -1.0,
the stronger the relationship.
Zero Correlation
• There is no relationship whatsoever
between the two variables.
Experimental Design
The Only Way to Show
Cause & Effect
Experimental Terms
• Variable – part of experiment that changes
• Independent Variable (IV)– controlled by
researcher. This variable causes something to
happen.
• Dependent Variable (DV) – watched by the
researcher to see the impact of the IV. This
variable is the effect that is caused by the IV.
• Good Way to Remember the difference: An IV
in your arm causes something to happen (DV)
• Confounding Variable – things that cannot be
controlled that can influence the experiment
Groups
• Experimental group – receives the treatment;
frequently a drug
• Control group – receives no treatment; usually
receives a placebo (fake drug)
Limitations of Experiments
• Conditions in an experiment may not reflect
conditions of real life.
• (Must simplify variables to get useful
information.)
• Ethical considerations in creating some
more “real life” situations
Research Ethics
• Confidentiality – participants are more
likely to be truthful if they know their
privacy is protected.
• Confidentiality can be broken if information
reveals harm to another person
Ethics
• Informed consent – some studies may have long
term threats or irreversible effects.
– Participants must be given a choice to participate after
being informed of the study.
• Deception is allowable when benefit outweighs
harm and participants receive full explanation at
its conclusion
Animal Research
• APA has rules for animals, too.
• Often used instead of humans when topic could
not be ethically studied on a human.
– Ex: Early separation studied by Harlow in 1959 with
monkeys.
• Animal experiments lead to solutions with
humans – eating disorders, drug treatments
• Still controversial due to the fact that animals can
be harmed in studies.