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Schacter
Gilbert
Wegner
PSYCHOLOGY
Chapter 2
The Methods Of
Psychology
Slides prepared by:
Melissa S. Terlecki, Cabrini College
Schacter
Gilbert
Wegner
PSYCHOLOGY
2.1
Empiricism: How to
Know Things
Empiricism: How to Know
Things

Three things that make people especially
difficult to study:
Complexity
 Variability
 Reactivity

Empiricism: How to Know
Things

Dogmatism: the tendency for people to cling to
their assumptions.
 Empiricism: originally a Greek school of
medicine that stressed the importance of
observation; now generally used to describe
any attempt to acquire knowledge by observing
objects or events.
 Method: a set of rules and techniques for
observation that allow researchers to avoid the
illusions, mistakes, and erroneous conclusions
that simple observation can produce.
4
Questions
 Why
is it so hard to study people
scientifically?
Schacter
Gilbert
Wegner
PSYCHOLOGY
2.2
The Science of
Observation: Saying
What
Culture and Community: Expecting a
Helping Hand? It Depends Where You Are

Observational study of helping behaviors
in a naturalistic context.

Helpfulness varied between locations.
Measurement

Observe: use your senses to learn about
something’s properties.
 Operational definition: a description of an
abstract property in terms of a concrete
condition that can be measured.
 Measure: a device that can detect the
measurable events to which an operational
definition refers.


defining and detecting.
for example, electromyograph (EMG): a device
that measures muscle contractions under the
surface of a person’s skin.
Questions
 How
could you measure
happiness?
Figure 2.1: Sources of Invalidity
(p. 36)
Measurement

Prerequisites for accurate measurement:
validity: the characteristic of an observation
that allows one to draw accurate inferences
from it.
 reliability: the tendency for a measure to
produce the same result whenever it is used
to measure the same thing.
 power: the tendency for a measure to
produce different results when it is used to
measure different things.

Samples
Case method: a method of gathering
scientific knowledge by studying a single
individual.
 Population: the complete collection of
participants who might possibly be
measured.


sample: the partial collection of people who
actually were measured in a study.
Questions
 How
can an exceptional case teach
us about normal behavior?
Demand Characteristics
Demand characteristics: those aspects
of an observational setting that cause
people to behave as they think an
observer wants or expects them to
behave.
 Naturalistic observation: a method of
gathering scientific knowledge by
unobtrusively observing people in their
natural environments.

Questions
 Why
do people act differently when
they know they’re being observed?
Demand Characteristics

Naturalistic observation cannot solve the
problem of demand characteristics.



Some events cannot be observed naturally.
Some observations can only be gathered through
direct interaction.
Private or anonymous responding, measuring
behaviors not susceptible to demand, and
blind procedures can minimize demand
characteristics.


cover stories.
filler items.
New York City Bar’s One-way
Mirror (p. 38)
Questions
 Why
is it sometimes important that
participants not be aware of an
experiment’s true purpose?
The Blind Observer
Expectations can influence observations.
 Expectations can influence reality.
 Double-blind observation: an
observation whose true purpose is
hidden from the researchers as well as
from the participant.

Questions
 When
might a computer run a better
experiment than a human being?
Financial Collapse in 2008 and
1929 (p. 40)
Schacter
Gilbert
Wegner
PSYCHOLOGY
2.3
The Science of
Explanation: Saying
Why
Correlation and Causation
Correlation: the “co-relationship” or
pattern of covariation between two
variables, each of which has been
measured several times.
 Variable: a property whose value can
vary or change.
 Third-variable correlation: the fact that
two variables may be correlated only
because they are both caused by a third
variable.

Table 2.1: Hypothetical Data of the Relationship
Between Happiness and Altruism (p. 41)
Questions
 Televised
violence and aggression
are correlated. Does that mean
televised violence causes
aggressiveness?
Figure 2.2: Causes of
Correlation (p. 42)
Matched Samples and Matched
Pairs

In order to eliminate the possibility that a third
variable (and not the independent variable)
caused changes in the dependent variable:


matched samples: an observational technique that
involves matching the average of the participants in
the experimental and control groups.
matched pairs: an observational technique that
involves matching each participant in the
experimental group with a specific participant in the
control group.
Hot Science: Establishing
Causality in the Brain
Brain damage may be related to
particular patterns of behavior, but that
relationship may or may not be causal.
 Ethically, we cannot experiment with
brain damage, but can temporarily
deactivate brain regions.


Transcranial magnetic stimulation (TMS)
Matched Samples and
Matched Pairs

Cannot dismiss all potential third
variables.

third-variable problem: the fact that the
causal relationship between two variables
cannot be inferred from the correlation
between them because of the ever-present
possibility of third-variable correlation.
Experimentation

Experiment: a technique for establishing the
causal relationship between variables, through
manipulation.




independent variable: the variable that is
manipulated in an experiment.
experimental group: one of the two groups of
participants created by the manipulation of an
independent variable in an experiment that is
exposed to the stimulus being studied.
control group: one of the two groups of
participants created by the manipulation of an
independent variable in an experiment that is not
exposed to the stimulus being studied.
dependent variable: the variable that is measured
in a study.
Questions
 In
what ways do we perform
experiments in everyday life?
Figure 2.3: Manipulation (p. 45)
Drawing Conclusions

Internal validity: the characteristic of an
experiment that allows one to draw accurate
inferences about the causal relationship
between an independent and dependent
variable.



An independent variable has been effectively
manipulated.
A dependent variable has been measured in an
unbiased way with a valid, powerful, and reliable
measure.
A correlation has been observed between the
independent and the dependent variable.
Drawing Conclusions

External validity: a characteristic of an
experiment in which the independent and
dependent variables are operationally defined
in a normal, typical, or realistic way.
 Theory: a hypothetical account of how and
why a phenomena occurs, usually in the form
of a statement about the causal relationship
between two or more properties.

hypothesis: a specific and testable prediction that
is usually derived from a theory.
Questions
 Should
variables be defined as they
typically are in the real world?
Drawing Conclusions

Generalizing from the sample to the
larger population:


random sampling: a technique for
choosing participants that ensures that
every member of a population has an equal
chance of being included in the sample.
Nonrandom samples are acceptable.
Sometimes generality doesn’t matter.
 Sometimes generality can be determined.
 Sometimes generality can be assumed.

Questions
 When
can a sample teach us about
a population?
Schacter
Gilbert
Wegner
PSYCHOLOGY
2.4
The Ethics of Science:
Saying Please and
Thank You
The Ethics of Science: Saying
Please and Thank You

Code of ethics (APA, 1958):





informed consent: a written agreement to
participate in a study made by a person (adult) who
has been informed of all the risks that participation
may entail.
freedom from coercion.
protection from harm.
risk-benefit analysis.
debriefing: a verbal description of the true nature
and purpose of a study that psychologists provide
to people after they have participated in the study.
The Ethics of Science: Saying
Please and Thank You
Institutional Review Board (IRB)
approval required.
 Non-human psychological research
performed.

ethical treatment and rights.
 costs versus benefits.
 moral dilemma.

PeTA and the Unethical
Treatment of Animals (p. 50)
Questions
 Is
it ever justifiable to harm a human
or nonhuman research participant?
Where Do You Stand? The
Morality of Immoral Experiments

Nazi doctors during World War II
unethically experimented on prisoners.

Controversial publication of data results.