CHAPTER 1

THINKING CRITICALLY WITH PSYCHOLOGICAL SCIENCE

The Need for Psychological Science

1-1 How does our everyday thinking sometimes lead us to a wrong conclusion?

Our everyday thinking can be perilous because of three phenomena: hindsight bias, overconfidence, and a tendency to perceive patterns in random events. Hindsight bias (also called the “I-knew-it-all-along phenomenon”) is the tendency to believe, after learning an outcome, that we would have foreseen it. Overconfidence in our judgments results partly from our bias to seek information that confirms them. These tendencies, plus our eagerness to perceive patterns in random events, lead us to overestimate our intuition. Although limited by the testable questions it can address, scientific inquiry can help us overcome our intuition’s biases and shortcomings.

1-2 How do the scientific attitude’s three main components relate to critical thinking?

The scientific attitude equips us to be curious, skeptical, and humble in scrutinizing competing ideas or our own observations. This attitude carries into everyday life as critical thinking, which puts ideas to the test by examining assumptions, appraising the source, discerning hidden values, evaluating evidence, and assessing conclusions.

Research Strategies: How Psychologists Ask and Answer Questions

1-3 How do theories advance psychological science?

Psychological theories are explanations that apply an integrated set of principles to organize observations and generate hypotheses—predictions that can be used to check the theory or produce practical applications of it. By testing their hypotheses, researchers can confirm, reject, or revise their theories. To enable other researchers to replicate the studies, researchers report them using precise operational definitions of their procedures and concepts. If others achieve similar results, confidence in the conclusion will be greater.

1-4 How do psychologists use case studies, naturalistic observations, and surveys to observe and describe behavior, and why is random sampling important?

Descriptive methods, which include case studies, naturalistic observations, and surveys, show us what can happen, and they may offer ideas for further study. The best basis for generalizing about a population is a representative sample; in a random sample, every person in the entire population being studied has an equal chance of participating. Descriptive methods cannot show cause and effect because researchers cannot control variables.

C-3

1-5 What does it mean when we say two things are correlated, and what are positive and negative correlations?

When we say two things are correlated, we are saying that they accompany each other in their movements. In a positive correlation, two factors increase or decrease together. In a negative correlation, one item increases as the other decreases. The strength of their relationship is expressed as a correlation coefficient, which ranges from +1.00 (a perfect positive correlation) through 0 (no correlation) to −1.00 (a perfect negative correlation). Their relationship may be displayed in a scatterplot, in which each dot represents a value for the two variables.

1-6 What is regression toward the mean?

Regression toward the mean is the tendency for extreme or unusual scores to fall back toward their average.

1-7 Why do correlations enable prediction but not cause-effect explanation?

Correlations enable prediction because they show how two factors move together, either positively or negatively. A correlation can indicate the possibility of a cause-effect relationship, but it does not prove the direction of the influence, or whether an underlying third factor may explain the correlation.

1-8 What are the characteristics of experimentation that make it possible to isolate cause and effect?

To discover cause-effect relationships, psychologists conduct experiments, manipulating one or more factors of interest and controlling other factors. Using random assignment, they can minimize confounding variables, such as preexisting differences between the experimental group (exposed to the treatment) and the control group (given a placebo or different version of the treatment). The independent variable is the factor the experimenter manipulates to study its effect; the dependent variable is the factor the experimenter measures to discover any changes occurring in response to the manipulations. Studies may use a double-blind procedure to avoid the placebo effect.

1-9 Can laboratory experiments illuminate everyday life?

Researchers intentionally create a controlled, artificial environment in the laboratory in order to test general theoretical principles. These general principles help explain everyday behaviors.

1-10 Why do psychologists study animals, and what ethical guidelines safeguard human and animal research participants? How do human values influence psychology?

Some psychologists are primarily interested in animal behavior; others want to better understand the physiological and psychological processes shared by humans and other species. Government agencies have established standards for animal care and housing. Professional associations and funding agencies also establish guidelines for protecting animals’ well-being. The APA ethics code outlines standards for safeguarding human participants’ well-being, including obtaining their informed consent and debriefing them later.

Psychologists’ values influence their choice of research topics, their theories and observations, their labels for behavior, and their professional advice. Applications of psychology’s principles have been used mainly in the service of humanity.

C-4

Statistical Reasoning in Everyday Life

1-11 How do we describe data using three measures of central tendency, and what is the relative usefulness of the two measures of variation?

A measure of central tendency is a single score that represents a whole set of scores. Three such measures that we use to describe data are the mode (the most frequently occurring score), the mean (the arithmetic average), and the median (the middle score in a group of data).

Measures of variation tell us how diverse data are. Two measures of variation are the range (which describes the gap between the highest and lowest scores) and the standard deviation (which states how much scores vary around the mean, or average, score). Scores often form a normal (or bell-shaped) curve.

1-12 How do we know whether an observed difference can be generalized to other populations?

To feel confident about generalizing an observed difference to other populations, we would want to know that the sample studied was representative of the larger population being studied; that the observations, on average, had low variability; that the sample consisted of more than a few cases; and that the observed difference was statistically significant.