UNIT 1: Scientific Foundations of Psychology
PART II: Research Methods: Thinking Critically With Psychological Science
5-1 Describe how theories advance psychological science.
5-2 Explain how psychologists use case studies, naturalistic observations, and surveys to observe and describe behavior, and why random sampling is important.
Learning Targets
In Module 1 we discussed the three elements �of the scientific attitude.
curiosity
skepticism
humility
The Scientific Method
Psychologists use the scientific method to support their scientific attitude. It is a self-correcting process using observation and analysis to evaluate ideas.
How does a theory advance science?
What is a theory?
an explanation using
an integrated set of principles
that organizes observations and
predicts behaviors or events
So for instance…
TRY IT
What theories do you have about….
…how exercise relates to stress?
…the way caffeine impacts memory?
…how smiling impacts mood?
How does a hypothesis �advance science?
What is a hypothesis?
a testable prediction,
often implied by a theory
So for instance…
To test our theory of sleep’s effects on memory,
our hypothesis might be that
when sleep deprived, people will
remember less from the day before.
What is the difference between a �theory and a hypothesis?
theory
using our observations to explain behavior
hypothesis
predictions about behavior that can be tested
A testable prediction that drives research is known as a(n)
1. What Would You Answer?
What comes next?
…research.
Remember.. The rat is always right.
The results of our experiment will
either support our theory or
lead us to revise or reject it.
From theory to hypothesis to…
Let’s consider this hypothesis:
When sleep deprived, people will remember less from the day before.
What do we mean by sleep deprived?
2 hours fewer than usual? No sleep at all for a week?
How will we know someone “remembers less”?
Less than what? Less than whom?
What is an operational definition?
A carefully worded statement of
the exact procedures (operations)
used in a research study.
For example, human intelligence may be
operationally defined as what an
intelligence test measures.
The variable would then need to be quantified…so in this instance, human intelligence would be the score on an intelligence test.
What is an operational definition for �our hypothesis?
sleep deprived
We’ll define that as 2 fewer
hours than the subject’s normal
amount of sleep.
remember less
We can compare the number of words correctly recalled after a normal night of sleep with that of a shortened sleep night.
Why is an operational definition important?
operational definition
If we specifically define what we mean by
“sleep loss” or “caffeine” or
“smiling”…
replication
…we can repeat the experiment precisely as it was conducted the first time.
Replication is confirmation.
Work with a partner to develop a hypothesis for the theories below.
Music helps plants grow.
Ginger tea helps reduce hyperactivity in teens
Eating junk food causes weight gain.
TRY IT
Now that you have your hypothesis… practice operationally defining the terms.
Let’s think about operational definitions.
Plants that are exposed to music show increased growth.
TRY IT
What type of music will you play?
How loud will you play the music?
How long will the plants be exposed to music?
What types of plants will you use?
How will you measure growth?
How often will you take your measurements?
Let’s think about operational definitions again.
Drinking ginger tea reduces hyperactivity in teens.
TRY IT
How much tea will each subject drink?
What are the ingredients in the tea?
How often will the subject drink tea?
How will you measure hyperactivity?
What age are the teens?
Are the teens girls or boys?
Do the teens have ADHD?
Let’s think more about operational definitions.
Eating junk food causes weight gain.
TRY IT
How do you define junk food?
What brands and products will the subjects consume?
How much and how often will the subjects eat?
How will you measure weight gain?
What weight ranges are the subjects in at the start of the experiment?
How active are the participants?
Men or women?
How can we test hypotheses and �refine theories?
descriptive methods
correlational methods
experimental methods
What are three descriptive methods?
case studies
naturalistic observation
surveys and interviews
What is a case study?
A descriptive technique
in which one individual
or group is studied in depth
in the hope
of revealing universal
principles.
How do psychologists use case �studies to observe and describe behavior?
one individual
one group
What are the strengths and limitations �of the case study method?
strengths
for further study.
limitations
What is naturalistic observation?
A descriptive technique of observing
and recording behavior in
naturally occurring situations
without trying to manipulate or
control the situation.
How do psychologists use the �naturalistic observation method�to observe and describe behavior?
watching chimpanzees in the jungle
How else do psychologists use the �naturalistic observation method�to observe and describe behavior?
Psychologists Mehl and Pennebaker attached voice recorders to 79 college students to listen in on their day-to-day conversations.
How can the �naturalistic observation method�describe behavior?
Counting positive and negative words in 504 million
Twitter messages from 84 countries
What are the strengths and limitations �of the naturalistic observation method?
strengths
limitations
What is a survey?
a descriptive technique
for obtaining the self-reported
attitudes or behaviors of a
particular group, usually by
questioning a representative,
random sample of the group.
How do psychologists use �the survey method�to observe and describe behavior?
half of all Americans reported experiencing more happiness and enjoyment than worry
and stress on the previous day (Gallup, 2010).
1 in 5 people across 22 countries report believing that alien beings have come to Earth and now walk among us disguised as humans (Ipsos, 2010).
68 percent of all humans—some 5 billion people—say that religion is important in their daily lives (Diener et al., 2011).
Which of the following questions is best investigated by means of a survey?
2. What Would You Answer?
What are the strengths and limitations �of the survey method?
strengths
limitations
Which of the two phrases below would you be in favor of supporting?
Gun safety laws or gun control laws?
Aid to the needy or welfare?
Revenue enhancers or taxes?
TRY IT
Let’s consider the problem of �wording effects in surveys:
Do you support aid to the needy?
Turns out that more people respond favorably to the first statement than the second.
The way we word our survey has significant effects on the responses.
Do you support welfare?
Let’s consider the problem of �sampling bias in surveys:
Survey finds 94% of people support federal funding
of the space program.
What questions should I ask?
Where was the survey conducted?
Who was in the sample?
Why is the survey location a possible problem?
Survey finds 94% of people support federal funding
of the space program.
Where was the survey conducted? How could each of these survey locations change the results?
Washington D.C.
At a screening of Star Wars
In a small Iowa town
At a
political event
Why is the survey population a possible problem?
Survey finds 94% of people support federal funding
of the space program.
Who was in the survey sample? Do these subgroups have different goals? Priorities?
Naval aviators
Students at a technical college
Prison inmates
Teenagers
What is a representative sample?
If you wanted to survey students at your school, how would you choose whom to survey?
A representative sample has the same distribution of demographic qualities in it as the population as a whole. For instance…if the student population at the school is 25% Hispanic students, 30% Asian students, 35% African American students, and 10% Caucasian students, your sample should reflect those percentages.
If your school is 50% male and 50% female, equal numbers of both sexes should be represented in your sample.
What is a population and a random sample?
population
All those in a group
being studied,
from which samples
may be drawn.
random sample
A sample that
fairly represents a population
because each member
has an
equal chance
of inclusion.
If you wanted to survey high school students about drug use…
How would you identify your population?
How would you create a random sample?
TRY IT
Which of the following is most important when conducting survey research?
3. What Would You Answer?
Dr. Cheema is interested in studying the prevalence of cheating on exams at her local high school.
Describe one advantage of using each of the following research methods to study this topic:
4. What Would You Answer?
Learning Target 5-1 Review
Describe how theories advance
psychological science.
Learning Target 5-2 Review
Explain how psychologists use
case studies, naturalistic observations,
and surveys to observe and describe behavior, and why random sampling is important
observations, and surveys, show us what can happen and offer ideas for future research.