ﴀﴀ © 2008 The McGraw-Hill Companies, Inc. Chapter 2: Psychological Research.

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Chapter 2: Psychological Research

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The Scientific Method

• The approach used by psychologists to systematicallysystematically acquire knowledge and understanding about behavior and other phenomena of interest

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Scientific Method: The Process

Conduct Research

Identify a Question of Interest

Develop anexplanation

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Scientific Method: Developing Explanations

• Theories– Broad explanations and predictions

concerning phenomena of interest

• Hypothesis– A prediction stated in a way that

allows it to be tested

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Scientific Method: Conducting Research

• Research – Systematic inquiry aimed at the discovery of

new knowledge

• Operationalization– Process of translating a hypothesis into

specific, testable procedures that can be measured and observed

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Conducting Psychological Research

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Research Methods

• Archival research– Use of existing data in

order to test a hypothesis

• Naturalistic research– Observation of

naturally occurring behavior without intervention

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Research Methods

• Survey research– A sample of people is asked a

series of questions about their behavior, thoughts, and attitudes in order to represent a larger population

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Research Methods

• Case study– An in-depth, intensive investigation of

an individual or small group of people– Drawback? It is impossible to make

valid generalizations to a larger population

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Research Methods

• Correlational research– The relationship between two sets of variables is

examined to determine whether they are associated or “correlated”

– Correlation does not mean “causation”– Ranges from +1 to -1

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Research Methods

• Correlational research

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Correlational Research

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Research Methods

• Variables– Behaviors, events, or other characteristics

that can change, or vary in some way

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Research Methods

• Experiment– The relationship between two (or

more) variables is investigated by deliberately producing a change in one variable in a situation and observing the effects of that change on other aspects of the situation

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Experimental Research

Control Group:A group that receives

no treatment

Experimentalmanipulation:The change that an

experimenterdeliberately produces

in a situation

Experimental group:

Any group receivinga treatment

Treatment:The manipulation

implementedby the experimenter

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Experimental Research

• Independent Variable– The variable that is manipulated by an

experimenter

• Dependent Variable– The variable that is measured and is expected

to change as a result of changes caused by the experimenter’s manipulation of the independent variable

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Experimental Research: Final Step

• Random assignment to condition– Participants are assigned to different

experimental groups or “conditions” on the basis of chance and chance alone

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Experimental Research: Final Step

• Significant outcome– Meaningful results that make it possible for

researchers to feel confident that they have confirmed their hypotheses

• Replication– Repetition of findings using other procedures

in other setting

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Moving Beyond the Study

• Latane’ and Darley’s experiment

• Group size can cause changes in the degree of helping behavior

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Critical Research Issues

• Ethics

•Protection of participants from physical and mental harm

•The right of participants to privacy regarding their behavior

•The assurance that participation in research is completely voluntary

•The necessity of informing participants about the nature of procedures before their participation in the experiment

•Informed consent

•Deception and debriefing

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Critical Research Issues

• Choosing participants who represent the scope of human behavior

• Should animals be used in research?

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Threats to Experiment Validity

• Experimental bias– Factors that distort how the independent

variable affects the dependent variable in an experiment

• Experimenter expectations• Participant expectations

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Threats to Experiment Validity

• Placebo– A false treatment, such as a pill, “drug”, or

other substance, without any significant chemical properties or active ingredient

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Becoming an Informed Consumer of Psychology

• What was the purpose of the research?

• How well was the study conducted?

• Are the results presented fairly?