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
Schacter
Gilbert
Wegner
PSYCHOLOGY
2.2
The Science of
Observation: Saying
What
Empiricism involves using
observation to gain
knowledge about the world.
Because causal observation
is prone to error, sciences
have developed methods for
observation.
Method: a set of rules and
techniques for observation.
Questions
 Why
is it so hard to study people
scientifically?
Empiricism: How to Know
Things

Three things that make people especially
difficult to study:
Complexity
 Variability
 Reactivity

Observe: use your senses to learn about
something’s properties.
Measurement
 Measure:
a device that can detect
the measurable events to which an
operational definition refers.
Operational definition: a description of
an abstract property in measurable
terms.
 For example

Try to give a definition of ‘length’
Length: the change in the location of light
over time.
So…
 ‘A bookshelf is a meter in length’:


We are saying how long it takes a particle of
light to travel from one end of the shelf to
the other.
Question:
 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.

Same Question:

How would you measure happiness?
Another Question (sorry)
 How
do you know what to measure
with so your test will be reliable?
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.
Question:
 Why
do people act differently when
they know they’re being observed?
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.
New York City Bar’s One-way
Mirror
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.
Questions
 Why
is it sometimes important that
participants not be aware of an
experiment’s true purpose?
Expectations can influence observations.
 Expectations can influence reality.


OK, we have our reliable measurement
and constructed a representative
sample. Now, how do we apply that
measurement to the sample in the most
accurate way possible?
The Blind Observer

Double-blind observation: an
observation whose true purpose is
hidden from the researchers as well as
from the participant.
Schacter
Gilbert
Wegner
PSYCHOLOGY
2.3
The Science of
Explanation: Saying
Why
Quick Review
:
So, empiricism is studying the world
around us, using our 5_________
through ____________.
But, our senses sometimes let us down,
so we’ve come up with a
_____________ (a set of rules and
techniques for observation) to gather
information.
So, empiricism is studying the world around us,
using our 5 SENSES through OBSERVATION.
But, our senses sometimes let us down, so
we’ve come up with a METHOD (a set of rules
and techniques for observation) to gather
information.
Next, we define what we are trying to
measure and select a
_____________(a partial collection of
objects of events that is measured) to
do a test.
Next, we define what we are
trying to measure and select
a SAMPLE (a partial
collection of objects of events
that is measured) to do a
test.
Unfortunately, some people act differently
when they are being watched
( _________-characteristic), so psychologists
employ _____________-observation and
double-________observation to affectively
gather information.
Unfortunately, some people act differently when
they are being watched
( DEMAND-characteristic), so psychologists
employ NATURALISTIC-observation and
double-BLIND observation to affectively
gather information.
What if we wanted to study the
relationship between the amount
of violence a child watches on TV
and the aggressiveness of the
child’s behavior?
Questions
 Televised
violence and aggression
are correlated. Does that mean
televised violence causes
aggressiveness?
Correlation and Causation

Correlation: the “co-relationship”
between two variables

Variable: a property whose value can
vary or change. (TV & Aggression)

Third-variable correlation: the fact that
two variables may be correlated only
because they are both caused by a third
variable. (Lack of Adult Supervision)
Figure 2.2: Causes of
Correlation (p. 42)
But, there is a problem…

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.
So…

Experiment: a technique for establishing the
causal relationship between variables, through
manipulation

Experiments always involve manipulation
 The
variable that is manipulated in
an experiment is called the:
independent variable:
Which leads to two groups:
 experimental
group: exposed to the
stimulus being studied.
 control
group: not exposed to the
stimulus being studied.

dependent variable: the variable that is
measured in a study (Aggression)
Figure 2.3: Manipulation (p. 45)
Questions
 In
what ways do we perform
experiments in everyday life?
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.

Theory: a hypothetical account of how and
why a phenomenon occurs

Hypothesis: a specific and testable
prediction made by a theory
(If this…, then…)
Drawing Conclusions

External validity: clearly defining the
independent (TV watching) and dependent
(Aggression) variables
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.