Psychological Science, 3e: W. W. Norton StudySpace

What Is Scientific Inquiry?

• The Scientific Method Depends on Theories, Hypotheses, and Research: Scientific inquiry relies on objective methods and empirical evidence to answer testable questions. Interconnected ideas or models of behavior (theories) yield testable predictions (hypotheses), which are tested in a systematic way (research) by collecting and evaluating evidence (data).
• Unexpected Findings Can Be Valuable: Unexpected (serendipitous) discoveries sometimes occur, but only researchers who are prepared to recognize their importance will benefit from them.

What Are the Types of Studies in Psychological Research?

• Descriptive Studies Involve Observing and Classifying Behavior: Researchers observe and describe naturally occurring behaviors to pro- vide a systematic and objective analysis.
• Correlational Designs Examine How Variables Are Related: Correlational studies are used to examine how variables are naturally related in the real world, but cannot be used to establish causality or the direction of a relationship (which variable caused changes in another variable). Correlational reasoning occurs in many contexts, so readers need to be able to recognize correlational designs in everyday contexts, not just when reading research reports.
• An Experiment Involves Manipulating Conditions:In an experiment, researchers control the variations in the conditions that the participant experiences (independent variables) and measure the outcomes (dependent variables) to gain an understanding of causality. Researchers need a control group to know if the experiment had an effect.
• Random Assignment Is Used to Establish Equivalent Groups: Researchers sample participants from the population they want to study (e.g., all women who work). They use random sampling when everyone in the population is equally likely to participate in the study, a condition that rarely occurs. To establish causality between an intervention and an outcome, all participants must be equally likely to be in the experimental group or the control group, to control for preexisting group differences.

What Are the Data Collection Methods of Psychological Science?

• Observing Is an Unobtrusive Strategy: Data collected by observation must be defined clearly and collected systematically. Bias may occur in the data because the participants are aware they are being observed or because of the observer's expectations.
• Case Studies Examine Individual Lives and Organizations: A case study, one kind of descriptive study, examines an individual or an organization. An intensive study of an individual or organization can be useful for examining an unusual participant or unusual research question. Interpretation of a case study, however, can be subjective.
• Asking Takes a More Active Approach: Surveys, questionnaires, and interviews can be used to directly ask people about their thoughts and behaviors. Self-report data may be biased by the respondents' desire to present themselves in a particular way (e.g., smart, honest). Culturally sensitive research recognizes the differences among people from different cultural groups and from different language backgrounds.
• Response Performance Measures Information Processing: Measuring reaction times and reaction accuracy and asking people to make stimulus judgments are methods used to examine how people respond to psychological tasks.
• Body/Brain Activity Can Be Measured Directly: Electro- physiology (often using an electroencephalograph, or EEG) measures the brain's electrical activity. Brain imaging is done using positron emission tomography (PET), magnetic resonance imaging (MRI), and functional magnetic resonance imaging (fMRI). Transcranial magnetic stimulation (TMS) disrupts normal brain activity, allowing researchers to infer the brain processing involved in particular thoughts, feelings, and behaviors.
• Research with Animals Provides Important Data: Research involving nonhuman animals provides useful, although simpler, models of behavior and of genetics. The purpose of such research may be to learn about animals' behavior or to make inferences about human behavior.
• There Are Ethical Issues to Consider: Ethical research is governed by a variety of principles that ensure fair and informed treatment of participants.

How Are Data Analyzed and Evaluated?

• Good Research Requires Valid, Reliable, and Accurate Data: Data must be meaningful (valid) and their measurement reliable (i.e., consistent and stable) and accurate.
• Descriptive Statistics Provide a Summary of the Data: Measures of central tendency and variability are used to describe data.
• Correlations Describe the Relationships between Variables: A correlation is a descriptive statistic that describes the strength and direction of the relationship between two variables. Correlations close to zero signify weak relationships; correlations near 1 or 1 signify strong relationships.
• Inferential Statistics Permit Generalizations: Inferential statistics allow us to decide whether differences between two or more groups are probably just chance variations (suggesting that the populations the groups were drawn from are the same) or whether they reflect true differences in the populations being compared.

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