Thinking Critically With Psychological Science

Preview

The scientific attitude reflects an eagerness to skeptically scrutinize competing ideas with an open-minded humility before nature. This attitude, coupled with scientific principles for sifting reality from illusion, prepares us to think criti cally. Three reliable phenomena—hindsight bias, judgmen-tal overconfidence, and the tendency to perceive order in random events—illustrate the limits of everyday intuition and our need for scientific inquiry and critical thinking.

Psychologists construct theories that organize observations and imply testable hypotheses. In their research, they use case studies, naturalistic observation, and surveys to describe behav-ior; correlation to assess the relationship between variables; and experimentation to uncover cause-effect relationships. Researchers use statistics to describe their data, to assess relationships between variables, and to determine whether differences are significant.

This chapter concludes by briefly answering several questions that students commonly ask about psychology. These include concern over the simplification of reality in laboratory experi-ments, the generalizability of research in terms of culture and gender, the purpose of animal stud-ies, the adequacy of research ethics, and the potential misuse of psychology’s knowledge.

NOTE: Several items in the Instructor’s Resources (indicated here by a †) have alternative uses. See the Instructor’s Resources for explanations of those uses.

Introductory Exercise: Fact or Falsehood?

The correct answers to Handout 1–1 are as follows: 1. F 2. T 3. F 4. T 5. F 6. F 7. T 8. F 9. F 10. F

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Thinking Critically With Psychological Science

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HANDOUT 1–1

Fact or Falsehood?

T F 1. Human intuition is remarkably accurate and free from error.

T F 2. Most people seem to lack confidence in the accuracy of their beliefs.

T F 3. Most people suffer from unrealistically low self-esteem.

T F 4. Research suggests that college students spend more than 25 percent of their waking hours in conversation.

T F 5. The opinions of 1500 randomly selected people can provide a very accurate picture of the opinions of an entire nation.

T F 6. The scientific finding that depressed people tend to have low self-esteem proves that depression causes people to be down on themselves.

T F 7. The purpose of the experiment is to re-create behaviors exactly as they occur in everyday life.

T F 8. Under ethical and legal guidelines, researchers must ensure the comfort, health, and humane treatment of animals.

T F 9. As a science, psychology is objective and value-free.

T F 10. The wealthiest 20 percent in the United States possess 58 percent of the wealth.

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Guide

Learning Objectives

Every question in the Test Banks is keyed to one of these objectives.

The Need for Psychological Science 1-1. Explain how our everyday thinking sometimes leads us to a wrong conclusion. 1-2. Explain how the three main components of the scientific attitude relate to critical thinking.

Research Strategies: How Psychologists Ask and Answer Questions 1-3. Describe how theories advance psychological science. 1-4. Describe how psychologists use case studies, naturalistic observations, and surveys to observe and describe

behavior, and explain why random sampling is important. 1-5. Explain what it means when we say two things are correlated, and describe positive and negative correlations. 1-6. Define regression toward the mean. 1-7. Discuss why correlations enable prediction but not cause-effect explanation. 1-8. Describe the characteristics of experimentation that make it possible to isolate cause and effect. 1-9. Discuss whether laboratory conditions can illuminate everyday life. 1-10. Explain why psychologists study animals, and describe the ethical guidelines that safeguard human and animal

research participants. Discuss how human values influence psychology.

Statistical Reasoning in Everyday Life 1-11. Explain how we describe data using three measures of central tendency, and discuss the relative usefulness of

the two measures of variation. 1-12. Explain how we know whether an observed difference can be generalized to other populations.

The Need for Psychological Science

Why We Cannot Rely on Intuition and Common Sense

u Lectures: Misremembering the Causes of Behavior; Extraordinary Events and Chance: Your Birth Date in Pi?) u Exercises: The Limits of Human Intuition; The Birthday Coincidence and Other Remarkable Facts; The

Hindsight Bias and Predicting Research Outcomes; The Overconfidence Phenomenon; Student Overconfidence; Overconfidence and the Confirmation Bias; The Gambler’s Fallacy

u Exercise/Project: The Propensity Effect

1-1. Explain how our everyday thinking sometimes leads us to a wrong conclusion.

Intuition is an effortless, immediate, automatic feeling or thought, as contrasted with explicit, conscious reasoning. The hindsight bias, also known as the I-knew-it-all-along phenomenon, is the tendency to believe, after learning an outcome, that one would have foreseen it. Finding out that something has happened makes it seem inevitable. Thus, after learning the results of a study in psychology, they may seem to be obvious common sense. However, experiments have found that events seem far less obvious and predictable beforehand than in hindsight. Sometimes, psy-chological findings even jolt our common sense.

Our everyday thinking is also limited by our tendency to think we know more than we do. Asked how sure we are of our answers to factual questions, we tend to be more confident than correct. Experts’ predictions of world events made with 80 percent confidence were right less than 40 per-cent of the time.

Another limitation in everyday thinking is the tendency to perceive order in random events because random sequences often don’t look random. In actual random sequences, patterns and streaks occur more often than people expect.

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The Scientific Attitude and Critical Thinking

u Lectures: Your Teaching Strategies and Critical Thinking†; Critical Thinking u Exercises: Exit Tickets (p. xx); Critical Inquiry and Psychology†; A Psychic Reading u Project: Evaluating Media Reports of Research†

1-2. Explain how the three main components of the scientific attitude relate to critical thinking.

The scientific attitude reflects a hard-headed curiosity to explore and understand the world with-out being fooled by it. The eagerness to skeptically scrutinize competing claims requires humility because it means we may have to reject our own ideas. This attitude, coupled with scientific prin-ciples for sifting reality from fantasy, helps us winnow sense from nonsense. It carries into every-day life as critical thinking in which we examine assumptions, appraise the source, discern hidden values, evaluate evidence, and assess conclusions.

Research Strategies: How Psychologists Ask and Answer Questions

The Scientific Method

u Exercise: Astrology and the Scientific Method u Projects/Exercises: Is Psychology a Science? Testing Proverbs u PsychSim 6: Understanding Psychological Research u LaunchPad: Research Methods

1-3. Describe how theories advance psychological science.

A useful theory is an explanation using an integrated set of principles that effectively organizes a wide range of observations and implies testable predictions, called hypotheses. By enabling us to test and reject or revise a particular theory, such predictions give direction to research. They specify in advance what results would support the theory and what results would disconfirm it. As an additional check on their own biases, psychologists report their results precisely with clear operational definitions of concepts. Such statements of the procedures used to define research variables allow others to replicate, or repeat, their observations. Often, research leads to a revised theory that better organizes and predicts observable behaviors or events.

Description

u Lectures: Case Studies; The Power of Vivid Cases; Surveys, Evaluation Apprehension, and Naturalistic Observation; Predicting Elections

u Exercises: The Wording of Survey Questions; Conducting a National Survey; An M&M’s Sampling Demonstration u Exercise/Lecture Break: Finding the Good and Bad in Case Studies u Project/Exercise: Naturalistic Observation in the Dining Hall

1-4. Describe how psychologists use case studies, naturalistic observations, and surveys to observe and describe behavior, and explain why random sampling is important.

The case study is the method by which psychologists analyze one or more individuals in great depth in the hope of revealing things true of us all. While individual cases can suggest fruitful ideas, any given individual may be atypical, making the case misleading.

Naturalistic observation consists of observing and recording behavior in natural environments. Like the case study and survey methods, this research strategy describes behavior but does not explain it.

The survey looks at many cases in less depth and asks people to report their behavior or opinions. Asking questions is tricky because even subtle changes in the order or wording of questions can dramatically affect responses. In everyday experience, we are tempted to generalize from a few vivid but unrepresentative cases. The survey ascertains the self-reported attitudes or behaviors of a population by questioning a representative, random sample.

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Correlation

u Lectures: Understanding Correlation†; Misinterpreting Correlations† u Exercises: Correlation and Predicting Exam Performance†; Correlating Test-Taking Time and Performance†;

Positive and Negative Correlations†; Displaying Scatterplots; Illusory Correlation†; Illusory Correlation Demonstration†; The Power of Disconfirming Evidence: Do Dreams Predict the Future?†

u Exercise/Project: Correlation Does Not Imply Causation u PsychSim 6: Correlation† u Television Show: Home Simpson and Illustory Correlation† u LaunchPad: Correlation and Causation

1-5. Explain what it means when we say two things are correlated, and describe positive and negative correlations.

When surveys and naturalistic observations reveal that one trait or behavior accompanies another, we say the two correlate. A correlation coefficient is a statistical measure of the relationship between two things (from –1.00 to +1.00). A positive correlation indicates a direct relationship, meaning that two things increase together or decrease together. A negative correlation indicates an inverse relationship: As one thing increases, the other decreases. Researchers depict scores on graphs called scatterplots; each point plots the value of two variables. The correlation coefficient helps us to see the world more clearly by revealing the extent to which two things relate.

1-6. Define regression toward the mean.

Noticing and recalling confirming instances of relationships results in illusory correlations. Illusory correlations feed an illusion of control—that chance events are subject to our personal control. The illusion that we can control uncontrollable events is fed by a statistical phenomenon called regression toward the mean—the tendency for unusual events (including emotions) to return to their average state.

1-7. Discuss why correlations enable prediction but not cause-effect explanation.

Perhaps the most irresistible thinking error is to assume that correlation proves causation. Correlation reveals how closely two things vary together and thus how well one predicts the other. However, the fact that events are correlated does not mean that one causes the other. Thus, while correlation enables prediction, it does not provide explanation.

Experimentation

u Exercise: Introducing the Experiment; Random Assignment; Main Effects and Interactions or “It All Depends”† u Projects/Exercises: The Placebo Effect; Identifying Variables and Groups and Correlational Versus Experimental

Studies u LaunchPad: Does Self-Confidence Intimidate Others?

1-8. Desscribe the characteristics of experimentation that make it possible to isolate cause and effect.

The experiment is a research method in which the investigator manipulates one or more factors to observe their effect on some behavior or mental process, while controlling other relevant factors. If a behavior changes when we vary an experimental factor, then we know the factor is having a causal effect.

In many experiments, control is achieved by randomly assigning people either to an experimental group, which is exposed to the treatment, or a control group, which is not exposed.

Often, the research participants are blind (uninformed) about what treatment, if any, they are receiving. One group might receive the treatment, while the other group receives an inert placebo (a pseudotreatment). Often, both the participant and the research assistant who collects the data will not know which condition the participant is in (the double-blind procedure). The placebo effect is well documented. Just thinking one is receiving treatment can lead to symptom relief.

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A variable is anything that varies. The independent variable is the experimental factor that is manipulated. It is the variable whose effect is being studied. The dependent variable is the vari-able that may change in response to the manipulations of the independent variable. It is the out-come factor. Confounding variables are factors other than the independent variable that might produce an effect.

u Lectures: Field and Laboratory Experiments†

1-9. Discuss whether laboratory conditions can illuminate everyday life.

The experimenter intends the laboratory experiment to be a simplified reality, one in which impor-tant features can be simulated and controlled. The experiment’s purpose is not to re-create the exact behaviors of everyday life but to test theoretical principles. It is the resulting principles—not the specific findings—that help explain many behaviors.

u Exercise: Psychological Research Methods

Psychology’s Research Ethics

u Lectures: APA Guidelines for Ethical Conduct in the Care and Use of Nonhuman Animals in Research; Invasion of Privacy; Research Ethics

u Exercises: Animal Rights; Teaching Ethics in the Introduction to Psychology Course: Research Methods u LaunchPad: Ethics in Animal Research: The Sad Case of Boee the Chimp; Ethics in Human Research: Violating

One’s Privacy; Death of a Subject: The Ethics of Mental Health Research

1-10. Explain why psychologists study animals, and describe the ethical guidelines that safeguard human and animal research participants. Discuss how human values influence psychology.

Some psychologists study animals out of an interest in animal behaviors. Others do so because knowledge of the physiological and psychological processes of animals enables them to better understand the similar processes that operate in humans.

The debate between animal protection organizations and researchers has raised two important issues: Is it right to place the well-being of humans above that of animals? What safeguards are in place to protect the well-being of animals in research? Many professional organizations and fund-ing agencies have developed extensive guidelines for the humane use of animals.

In their statements of ethical principles for the treatment of human participants, the U.S. APA and Britain’s BPS urge investigators to obtain informed consent, protect participants from harm and discomfort, treat information about individuals confidentially, and fully explain the research after-ward (debrief them).

u Lectures: Psychology and Human Values†; The Instructor’s Perspectives and Values† u Exercise: Observing Versus Interpreting†

Psychologists’ values can influence their choice of research topic, their theories and observations, their interpretations, and their professional advice.

Knowledge is power that can be used for good or evil. Applications of psychology’s principles have so far been mostly for the good, and psychology addresses some of humanity’s greatest prob-lems and deepest longings.

Statistical Reasoning in Everyday Life

Describing Data u Lecture: The Case for Statistical Analysis u Exercise: Teaching Statistical Concepts u Exercise/Project: Describing Data u Project: Organizing and Interpreting Data u PsychSim 6: Descriptive Statistics

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1-11. Explain how we describe data using the three measures of central tendency, and discuss the rela-tive usefulness of the two measures of variation.

Researchers use descriptive statistics to organize their data meaningfully. Measures of central ten-dency neatly summarize data. The mode is the most frequently occurring score in a distribution. The mean is the arithmetic average of a distribution, obtained by adding the scores and then divid-ing by the number of scores. If the distribution is skewed by even a few extreme scores, the mean will be biased. The median is the middle score in a distribution; half the scores are above it and half are below it.

The range of scores—the gap between the lowest and highest score—provides only a rough esti-mate of variation. The more standard measure of how scores deviate from one another is the stan-dard deviation, which describes how much scores vary around the mean score. It better gauges whether scores are packed together or dispersed because it uses information from each score. Many types of scores are distributed along a bell-shaped distribution, or a normal curve (normal distribution). Roughly 68 percent of the cases fall within one standard deviation of the mean. About 95 percent fall within two standard deviations.

Significant Differences

u Lectures: The Law of Large Numbers and the Gambler’s Ruin†; Differences Between Groups† u Exercises: More Cases Are Better Than Fewer†

1-12. Explain how we know whether an observed difference can be generalized to other populations.

Important principles to remember in making generalizations include the following:

a. Representative samples are better than biased samples. We are particularly prone to overgener-alize from vivid cases at the extremes.

b. Less-variable observations are better than those that are more variable. Averages are more reli-able when derived from scores with low variability.

c. More cases are better than fewer. Small samples provide less reliable estimates of the average than do large samples.

Psychologists use tests of statistical significance to help them determine whether differences between two groups are reliable. When the averages of the samples drawn from the groups are reliable, and the difference between them is relatively large, we say the difference has statistical significance. This means that the difference very likely reflects a real difference and is not due to chance variation between the samples. Given large enough or homogeneous enough samples, a dif-ference between them may be statistically significant yet have little practical significance.

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