The Need for Scientific Methodology
The Characteristics of Modern Science
The Objectives of Psychological Science
The Tools of Psychological Science
Scientific Explanation in Psychological Science
The Organization of the Text
How are science, methodology, and data
interrelated?
Science connotes content and process.
Methodology consists of the scientific
techniques we use to collect and evaluate data.
Data are the facts we gather using scientific
methods.
The Need for Scientific Methodology
What is commonsense psychology?
Heider called nonscientific data gathering
commonsense psychology.
This approach uses nonscientific sources
of data and nonscientific inference.
An everyday example is believing that
“opposites attract.”
The Need for Scientific Methodology
Explain nonscientific inference.
Nonscientific inference is the nonscientific use
of information to explain or predict behavior.
The gambler’s fallacy, overuse of trait
explanations, stereotyping, and overconfidence
bias illustrate this problem.
The Need for Scientific Methodology
What is the gambler’s fallacy?
In the gambler’s fallacy, people misuse data to
estimate the probability of an event, like when a
slot machine will pay off.
The Need for Scientific Methodology
Why is the overuse of trait explanations a problem?
When we overuse trait explanations to explain
others' behavior, we often make unwarranted
dispositional attributions and underuse
situational information.
This bias can reduce the accuracy of our
explanations and predictions.
The Need for Scientific Methodology
How can stereotyping mislead us?
In stereotyping, we falsely assume that specific
behaviors cluster together.
For example, since Imei is a Chinese-American
student, she must study 10 hours a day and
excel at math. In reality, she failed calculus.
Stereotypes ignore individual differences.
The Need for Scientific Methodology
Why is overconfidence bias a problem?
In overconfidence bias, we feel more confident
about our conclusions than is warranted by
available data.
This form of nonscientific inference can result in
erroneous conclusions when we don’t recognize
the limitations of supporting data.
The Need for Scientific Methodology
Why is the scientific mentality important?
Alfred North Whitehead’s scientific mentality
assumes that behavior follows a natural order
and can be predicted.
This assumption is essential to science. There is
no point to using the scientific method to gather
and analyze data if there is no implicit order.
The Characteristics of Modern Science
What makes data empirical?
Data are empirical when observed or
experienced.
Galileo’s empirical approach was superior
to Aristotle’s commonsense method.
Galileo correctly concluded that light objects
fall as rapidly as heavy ones in a vacuum.
The Characteristics of Modern Science
What is a law?
A law consists of statements generally
expressed as equations with few variables
that have overwhelming empirical support.
Laws, like the Laws of Thermodynamics,
are useful in the physical sciences.
The Characteristics of Modern Science
What is a theory?
A theory is an interim explanation; a set of
related statements used explain and predict
phenomena.
Theories integrate diverse data, explain
behavior, and predict new instances of behavior.
The Characteristics of Modern Science
What is good thinking and why is it important?
Good thinking is critical to the scientific method.
We engage in good thinking when data collection
and interpretation are systematic, objective, and
rational.
The Characteristics of Modern Science
What is parsimony?
The principle of parsimony is that we prefer
the simplest useful explanation.
For example, Crandall (1988) showed that
a social contagion model of bulimia
was more parsimonious than competing
explanations.
The Characteristics of Modern Science
How did Sir Karl Popper believe that science
advances?
Sir Karl Popper proposed that science advances
by revising theories based on the “weight of
evidence.”
Science is self-correcting as scientific
explanations and theories are challenged,
and revised or replaced.
The Characteristics of Modern Science
What role does the principle of modus tollens play in
science?
The principle of modus tollens allows us to
disprove statements using a single, contrary
observation.
We can never prove a statement because a
contradictory observation might be found later.
The Characteristics of Modern Science
How does replication advance science?
Replication is an exact or systematic repetition
of a study.
Replication increases our confidence in
experimental results by adding to the weight of
supporting evidence.
The Characteristics of Modern Science
What are the four main objectives of science?
The four main objectives of science are:
 description
 prediction
 explanation
 control
The Objectives of Psychological Science
What are the four main objectives of science?
Description is a systematic and unbiased
account of observed characteristics of behaviors.
Prediction is the capability of knowing in
advance when certain behaviors should occur.
Explanation is knowledge of the conditions that
reliably produce a behavior.
The Objectives of Psychological Science
What are the four main objectives of science?
Control is the use of scientific knowledge to
influence behavior.
The Objectives of Psychological Science
How does applied research differ from basic
research?
Applied research addresses real-world
problems like how to improve student graduation
rates.
Basic research tests theories and explains
psychological phenomena like helping behavior.
The Objectives of Psychological Science
What are the main tools of psychological science?
The main tools of psychological science are:
 observation
 measurement
 experimentation
The Tools of Psychological Science
What are the main tools of psychological science?
Observation is the systematic noting and
recording of events. Systematic means that
the procedures are consistently applied.
The events or their signs must be observable.
Observations must be objective so that there
can be strong agreement among raters.
The Tools of Psychological Science
What are the main tools of psychological science?
Measurement assigns numbers to objects,
events, or their characteristics. This is an
inherent feature of quantitative research.
Baron and colleagues (1985) measured anger
and depression using numerical scales.
The Tools of Psychological Science
What are the main tools of psychological science?
Experimentation is the process we use to test
the predictions we call hypotheses and establish
cause-and-effect relationships.
Experimentation is not always possible because
our predictions must be testable.
The Tools of Psychological Science
What are the requirements for an experiment?
We must be able to manipulate the independent
variable and measure its effect on the dependent
variable.
Ethical concerns or technological limitations may
prevent experimentation.
The Tools of Psychological Science
What are the requirements for an experiment?
An experiment requires that we create at
least two treatment conditions and randomly
assign subjects to these conditions.
In psychology experiments, we control
extraneous variables so we that we can
measure “what we intend to measure.”
Scientific Explanation
How does an experiment establish cause and
effect?
An experiment attempts to establish a causeand-effect relationship between the antecedent
conditions (IV) and subject behavior (DV).
Experiments establish a temporal relationship,
because causes must precede effects. However,
not all prior events are causes.
Scientific Explanation
What are pseudosciences?
A pseudoscience is any field of study that
gives the appearance of being scientific,
but has no true scientific basis and has not
been confirmed using the scientific method.
Modern pseudosciences include past life
regression, reparenting, and rebirthing.
Scientific Explanation