1.2 Research Strategies: How Psychologists Ask and Answer Questions

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Psychologists arm their scientific attitude with the scientific method—a self-correcting process for evaluating ideas with observation and analysis. In its attempt to describe and explain human nature, psychological science welcomes hunches and plausible-sounding theories. And it puts them to the test. If a theory works—if the data support its predictions—so much the better for that theory. If the predictions fail, the theory will be revised or rejected.

The Scientific Method

theory an explanation using an integrated set of principles that organizes observations and predicts behaviors or events.

1-3 How do theories advance psychological science?

In everyday conversation, we often use theory to mean “mere hunch.” Someone might, for example, discount evolution as “only a theory”—as if it were mere speculation. In science, a theory explains behaviors or events by offering ideas that organize what we have observed. By organizing isolated facts, a theory simplifies. By linking facts with deeper principles, a theory offers a useful summary. As we connect the observed dots, a coherent picture emerges.

hypothesis a testable prediction, often implied by a theory.

A theory about the effects of sleep on memory, for example, helps us organize countless sleep-related observations into a short list of principles. Imagine that we observe over and over that people with good sleep habits tend to answer questions correctly in class, and they do well at test time. We might therefore theorize that sleep improves memory. So far so good: Our principle neatly summarizes a list of facts about the effects of a good night’s sleep on memory.

Yet no matter how reasonable a theory may sound—and it does seem reasonable to suggest that sleep could improve memory—we must put it to the test. A good theory produces testable predictions, called hypotheses. Such predictions specify what results (what behaviors or events) would support the theory and what results would disconfirm it. To test our theory about the effects of sleep on memory, our hypothesis might be that when sleep deprived, people will remember less from the day before. To test that hypothesis, we might assess how well people remember course materials they studied before a good night’s sleep, or before a shortened night’s sleep (FIGURE 1.1). The results will either confirm our theory or lead us to revise or reject it.

Figure 1.1
The scientific method A self-correcting process for asking questions and observing nature’s answers.

operational definition a carefully worded statement of the exact procedures (operations) used in a research study. For example, human intelligence may be operationally defined as what an intelligence test measures.

Our theories can bias our observations. Having theorized that better memory springs from more sleep, we may see what we expect: We may perceive sleepy people’s comments as less insightful. The urge to see what we expect is ever-present, both inside and outside the laboratory. According to the bipartisan U.S. Senate Select Committee on Intelligence (2004), preconceived expectations that Iraq had weapons of mass destruction led intelligence analysts to wrongly interpret ambiguous observations as confirming that theory (much as people’s views of climate change may influence their interpretation of local weather events). This theory-driven conclusion then led to the preemptive U.S. invasion of Iraq.

replication repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding extends to other participants and circumstances.

As a check on their biases, psychologists report their research with precise operational definitions of procedures and concepts. Sleep deprived, for example, may be defined as “X hours less” than the person’s natural sleep. Using these carefully worded statements, others can replicate (repeat) the original observations with different participants, materials, and circumstances. If they get similar results, confidence in the finding’s reliability grows. The first study of hindsight bias aroused psychologists’ curiosity. Now, after many successful replications with differing people and questions, we feel sure of the phenomenon’s power. Although a “mere replication” of someone else’s research seldom makes headline news, recent instances of fraudulent or hard-to-believe findings have sparked calls for more replications (Asendorff et al., 2013). Replication is confirmation. Replication enables scientific self-correction. One Association for Psychological Science journal now devotes a section to replications and 72 researchers are collaborating on a “reproducibility project” that aims to replicate a host of recent findings (Open Science Collaboration, 2012). So, replications are increasing, and so far, most “report similar findings to their original studies” (Makel et al., 2012).

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In the end, our theory will be useful if it (1) organizes a range of self-reports and observations, and (2) implies predictions that anyone can use to check the theory or to derive practical applications. (Does people’s sleep predict their retention?) Eventually, our research may (3) stimulate further research that leads to a revised theory that better organizes and predicts what we know.

As we will see next, we can test our hypotheses and refine our theories using descriptive methods (which describe behaviors, often through case studies, surveys, or naturalistic observations), correlational methods (which associate different factors), and experimental methods (which manipulate factors to discover their effects). To think critically about popular psychology claims, we need to understand these methods and know what conclusions they allow.

Question

PLEXNafDp0Zw8cevMP7Ypooqa9xYP3ArAEZai4PpHFUDK176UnW6Y2s8AULHrXaLZ9ny1Wd4EdAbwJz676WpHTsdOTdDXJ7gTwVeZ2zMZIMzDUPflEmb/pw2FTXFrNjxCZ7gtnB7MbCHG3Ii26DqPPej4QZ7Er5WpiDgL5gQrXzWr5A7aXHyOppZUkvv++sSzcSsWDSnkahMdlyJf7Cg4SEIXulEgs0tDap22p0Lfc5xl2eW58ax8Q==
Possible sample answer: A theory is useful if it (a) organizes a range of self-reports and observations and (b) implies predictions that anyone can use to check the theory or derive practical applications.

RETRIEVAL PRACTICE

  • What does a good theory do?

It organizes observed facts. 2. It implies hypotheses that offer testable predictions and, sometimes, practical applications. 3. It often stimulates further research.

  • Why is replication important?

Psychologists watch eagerly for new findings, but they also proceed with caution—by awaiting other investigators’ repeating the experiment to see if the finding can be confirmed (the result replicated).

Description

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

The starting point of any science is description. In everyday life, we all observe and describe people, often drawing conclusions about why they act as they do. Professional psychologists do much the same, though more objectively and systematically, through

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The Case Study

“‘Well my dear,’ said Miss Marple, ‘human nature is very much the same everywhere, and of course, one has opportunities of observing it at closer quarters in a village’.”

Agatha Christie, The Tuesday Club Murders, 1933

Among the oldest research methods, the case study examines one individual or group in depth in the hope of revealing things true of us all. Some examples: Much of our early knowledge about the brain came from case studies of individuals who suffered a particular impairment after damage to a certain brain region. Jean Piaget taught us about children’s thinking after carefully observing and questioning only a few children. Studies of only a few chimpanzees have revealed their capacity for understanding and language. Intensive case studies are sometimes very revealing. They show us what can happen, and they often suggest directions for further study.

Freud and Little Hans Sigmund Freud’s case study of 5-year-old Hans’ extreme fear of horses led Freud to his theory of childhood sexuality. He conjectured that Hans felt unconscious desire for his mother, feared castration by his rival father, and then transferred this fear into his phobia about being bitten by a horse. As Chapter 14 will explain, today’s psychological science discounts Freud’s theory of childhood sexuality but acknowledges that much of the human mind operates outside our conscious awareness.

case study a descriptive technique in which one individual or group is studied in depth in the hope of revealing universal principles.

But atypical individual cases may mislead us. Unrepresentative information can lead to mistaken judgments and false conclusions. Indeed, anytime a researcher mentions a finding (Smokers die younger: 95 percent of men over 85 are nonsmokers) someone is sure to offer a contradictory anecdote (Well, I have an uncle who smoked two packs a day and lived to be 89). Dramatic stories and personal experiences (even psychological case examples) command our attention and are easily remembered. Journalists understand that, and often begin their articles with personal stories. Stories move us. But stories can mislead. Which of the following do you find more memorable? (1) “In one study of 1300 dream reports concerning a kidnapped child, only 5 percent correctly envisioned the child as dead” (Murray & Wheeler, 1937). (2) “I know a man who dreamed his sister was in a car accident, and two days later she died in a head-on collision!” Numbers can be numbing, but the plural of anecdote is not evidence. As psychologist Gordon Allport (1954, p. 9) said, “Given a thimbleful of [dramatic] facts we rush to make generalizations as large as a tub.”

The point to remember: Individual cases can suggest fruitful ideas. What’s true of all of us can be glimpsed in any one of us. But to discern the general truths that cover individual cases, we must answer questions with other research methods.

RETRIEVAL PRACTICE

  • We cannot assume that case studies always reveal general principles that apply to all of us. Why not?

Case studies involve only one individual or group, so we can’t know for sure whether the principles observed would apply to a larger population.

naturalistic observation a descriptive technique of observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation.

Naturalistic Observation

A second descriptive method records behavior in natural environments. These naturalistic observations range from watching chimpanzee societies in the jungle, to videotaping and analyzing parent-child interactions in different cultures, to recording racial differences in students’ self-seating patterns in a school lunchroom.

Naturalistic observation has mostly been “small science”—science that can be done with pen and paper rather than fancy equipment and a big budget (Provine, 2012). But new technologies are enabling “big data” observations. New smart-phone apps and body-worn sensors are expanding naturalistic observation. Using such tools, researchers can track willing volunteers—their location, activities, and opinions—without interference. The billions of people on Facebook, Twitter, and Google, for example, have created a huge new opportunity for big-data naturalistic observation. One research team analyzed all 30.5 billion international Facebook friendships formed over four years, and found that people tended to “friend up.” Those from countries with lower economic status were more likely to solicit friendship with those in higher-status countries than vice versa (Landis et al., 2014).

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Another research team studied the ups and downs of human moods by counting positive and negative words in 504 million Twitter messages from 84 countries (Golder & Macy, 2011). As FIGURE 1.2 shows, people seem happier on weekends, shortly after arising, and in the evenings. (Are late Saturday evenings often a happy time for you, too?)

Figure 1.2
Twitter message moods, by time and by day This illustrates how, without knowing anyone’s identity, big data enable researchers to study human behavior on a massive scale. It now is also possible to associate people’s moods with, for example, their locations or with the weather, and to study the spread of ideas through social networks. (Data from Golder & Macy, 2011.)

Like the case study, naturalistic observation does not explain behavior. It describes it. Nevertheless, descriptions can be revealing. We once thought, for example, that only humans use tools. Then naturalistic observation revealed that chimpanzees sometimes insert a stick in a termite mound and withdraw it, eating the stick’s load of termites. Such unobtrusive naturalistic observations paved the way for later studies of animal thinking, language, and emotion, which further expanded our understanding of our fellow animals. “Observations, made in the natural habitat, helped to show that the societies and behavior of animals are far more complex than previously supposed,” chimpanzee observer Jane Goodall noted (1998). Thanks to researchers’ observations, we know that chimpanzees and baboons use deception: Psychologists repeatedly saw one young baboon pretending to have been attacked by another as a tactic to get its mother to drive the other baboon away from its food (Whiten & Byrne, 1988).

A natural observer Chimpanzee researcher Frans de Waal (2005) reported, “I am a born observer…. When picking a seat in a restaurant I want to face as many tables as possible. I enjoy following the social dynamics—love, tension, boredom, antipathy—around me based on body language, which I consider more informative than the spoken word. Since keeping track of others is something I do automatically, becoming a fly on the wall of an ape colony came naturally to me.”

Naturalistic observations also illuminate human behavior. Here are four findings you might enjoy:

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Table 1.1
A Penny for Your Thoughts: The Inner Experience of University Students)

Naturalistic observation offers interesting snapshots of everyday life, but it does so without controlling for all the factors that may influence behavior. It’s one thing to observe the pace of life in various places, but another to understand what makes some people walk faster than others.

RETRIEVAL PRACTICE

An EAR for naturalistic observation Psychologists Matthias Mehl and James Pennebaker have used electronically activated recorders (EARs) to sample naturally occurring slices of daily life.
  • What are the advantages and disadvantages of naturalistic observation, such as Mehl and Pennebaker used in this study?

The researchers were able to carefully observe and record naturally occurring behaviors outside the artificiality of the lab. However, outside the lab they were not able to control for all the factors that may have influenced the everyday interactions they were recording.

The Survey

A survey looks at many cases in less depth. A survey asks people to report their behavior or opinions. Questions about everything from sexual practices to political opinions are put to the public. In recent surveys:

survey a descriptive technique for obtaining the self-reported attitudes or behaviors of a particular group, usually by questioning a representative, random sample of the group.

But asking questions is tricky, and the answers often depend on how questions are worded and respondents are chosen.

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Wording Effects Even subtle changes in the order or wording of questions can have major effects. People are much more approving of “aid to the needy” than of “welfare,” of “affirmative action” than of “preferential treatment,” of “not allowing” televised cigarette ads and pornography than of “censoring” them, and of “revenue enhancers” than of “taxes.” In another survey, adults estimated a 55 percent chance “that I will live to be 85 years old or older,” while comparable other adults estimated a 68 percent chance “that I will die at 85 years old or younger” (Payne et al., 2013). Because wording is such a delicate matter, critical thinkers will reflect on how the phrasing of a question might affect people’s expressed opinions.

population all those in a group being studied, from which samples may be drawn. (Note: Except for national studies, this does not refer to a country’s whole population.)

Random SamplingIn everyday thinking, we tend to generalize from samples we observe, especially vivid cases. Given (a) a statistical summary of a professor’s student evaluations and (b) the vivid comments of a biased sample (two irate students), an administrator’s impression of the professor may be influenced as much by the two unhappy students as by the many favorable evaluations in the statistical summary. The temptation to ignore the sampling bias and to generalize from a few vivid but unrepresentative cases is nearly irresistible.

random sample a sample that fairly represents a population because each member has an equal chance of inclusion.

So how do you obtain a representative sample of, say, the students at your college or university? It’s not always possible to survey the whole group you want to study and describe. How could you choose a group that would represent the total student population? Typically, you would seek a random sample, in which every person in the entire group has an equal chance of participating. You might number the names in the general student listing and then use a random number generator to pick your survey participants. (Sending each student a questionnaire wouldn’t work because the conscientious people who returned it would not be a random sample.) Large representative samples are better than small ones, but a small representative sample of 100 is better than an unrepresentative sample of 500.

With very large samples, estimates become quite reliable. E is estimated to represent 12.7 percent of the letters in written English. E, in fact, is 12.3 percent of the 925,141 letters in Melville’s Moby-Dick, 12.4 percent of the 586,747 letters in Dickens’ A Tale of Two Cities, and 12.1 percent of the 3,901,021 letters in 12 of Mark Twain’s works (Chance News, 1997).

Political pollsters sample voters in national election surveys just this way. Using some 1500 randomly sampled people, drawn from all areas of a country, they can provide a remarkably accurate snapshot of the nation’s opinions. Without random sampling, large samples—including call-in phone samples and TV or website polls—often merely give misleading results.

The point to remember: Before accepting survey findings, think critically. Consider the sample. The best basis for generalizing is from a representative sample. You cannot compensate for an unrepresentative sample by simply adding more people.

Question

+dOSXUXzlat9C6V3DwcGDZRYuURmwJ4/XXeYcQ2YLzcHJj2VVwuXsKmOIF+/fxpMNcYGNPlDol+j0u4RSr+JnAKx5gh9p9ntkof1gpMMdCFUHjjpMkWElJjrF4RsAOJ1ATbxzYb2l/nv3/ZzvtFzcs3FNHvRiSfYuy2/sXp+mi27URIJZSLbQrSDPF7+X+fzUdGSxK6jVQaVLV+9MG5O2fEsIhlpAi/05Bv4tVfzftKDYXKW/d6zdgN74JzYDoARv6ttWuZXBB7tac1JUzfr9SnKOSeK9RboGmfnW0M4qF0=
Possible sample answer: With descriptive methods, psychologists systematically observe and describe human behavior. Intensive case studies may reveal important information and may suggest directions for further study. However, describing a behavior does not explain it. For example, a case study of a person who fears heights may tell us why that particular person fears heights. But we cannot be sure that the principle observed will be true of all people. That person may be atypical. Surveys tell us what people “say” they think, but people may answer a survey in a way that makes them look good. Psychologists therefore need to take the next step and experiment in order to determine cause and effect.

RETRIEVAL PRACTICE

  • What is an unrepresentative sample, and how do researchers avoid it?

An unrepresentative sample is a survey group that does not represent the population being studied. Random sampling helps researchers form a representative sample, because each member of the population has an equal chance of being included.

Correlation

correlation a measure of the extent to which two factors vary together, and thus of how well either factor predicts the other.

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

correlation coefficient a statistical index of the relationship between two things (from −1.00 to +1.00).

Describing behavior is a first step toward predicting it. Naturalistic observations and surveys often show us that one trait or behavior is related to another. In such cases, we say the two correlate. A statistical measure (the correlation coefficient) helps us figure how closely two things vary together, and thus how well either one predicts the other. Knowing how much aptitude test scores correlate with school success tells us how well the scores predict school success.

scatterplot a graphed cluster of dots, each of which represents the values of two variables. The slope of the points suggests the direction of the relationship between the two variables. The amount of scatter suggests the strength of the correlation (little scatter indicates high correlation).

Throughout this book, we will often ask how strongly two things are related: For example, how closely related are the personality scores of identical twins? How well do intelligence test scores predict career achievement? How closely is stress related to disease? In such cases, scatterplots can be very revealing.

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Each dot in a scatterplot represents the values of two variables. The three scatterplots in FIGURE 1.3 illustrate the range of possible correlations from a perfect positive to a perfect negative. (Perfect correlations rarely occur in the real world.) A correlation is positive if two sets of scores, such as height and weight, tend to rise or fall together.

Figure 1.3
Scatterplots, showing patterns of correlation Correlations can range from +1.00 (scores on one measure increase in direct proportion to scores on another), to 0.00 (no relationship), to –1.00 (scores on one measure decrease precisely as scores rise on the other).

Saying that a correlation is “negative” says nothing about its strength. A correlation is negative if two sets of scores relate inversely, one set going up as the other goes down. The study of University of Nevada students discussed earlier found their reports of inner speech correlated negatively (−.36) with their reported psychological distress. Those who reported more inner speech tended to report somewhat less psychological distress.

Statistics can help us see what the naked eye sometimes misses. To demonstrate this for yourself, try an imaginary project. You wonder if tall men are more or less easygoing, so you collect two sets of scores: men’s heights and men’s temperaments. You measure the heights of 20 men, and you have someone else independently assess their temperaments from 0 (extremely calm) to 100 (highly reactive).

With all the relevant data right in front of you (TABLE 1.2), can you tell whether the correlation between height and reactive temperament is positive, negative, or close to zero?

Table 1.2
Height and Temperamental Reactivity of 20 Men

Comparing the columns in TABLE 1.2, most people detect very little relationship between height and temperament. In fact, the correlation in this imaginary example is positive, +.63, as we can see if we display the data as a scatterplot (FIGURE 1.4).

For an animated tutorial on correlations, visit LaunchPad’s Concept Practice: Positive and Negative Correlations.

Figure 1.4
Scatterplot for height and reactive temperament This display of data from 20 imagined people (each represented by a data point) reveals an upward slope, indicating a positive correlation. The considerable scatter of the data indicates the correlation is much lower than +1.00.

If we fail to see a relationship when data are presented as systematically as in TABLE 1.2, how much less likely are we to notice them in everyday life? To see what is right in front of us, we sometimes need statistical illumination. We can easily see evidence of gender discrimination when given statistically summarized information about job level, seniority, performance, gender, and salary. But we often see no discrimination when the same information dribbles in, case by case (Twiss et al., 1989).

The point to remember: A correlation coefficient helps us see the world more clearly by revealing the extent to which two things relate.

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RETRIEVAL PRACTICE

  • Indicate whether each association is a positive correlation or a negative correlation.
  1. The more children and youth used various media, the less happy they were with their lives (Kaiser, 2010). ______________
  2. The less sexual content teens saw on TV, the less likely they were to have sex (Collins et al., 2004). ______________
  3. The longer children were breast-fed, the greater their later academic achievement (Horwood & Ferguson, 1998). ______________
  4. The more income rose among a sample of poor families, the fewer psychiatric symptoms their children experienced (Costello et al., 2003). ______________

1. negative, 2. positive, 3. positive, 4. negative

Regression Toward the Mean

1-6 What is regression toward the mean?

regression toward the mean the tendency for extreme or unusual scores or events to fall back (regress) toward the average.

Correlations not only make visible the relationships we might otherwise miss, they also restrain our “seeing” nonexistent relationships. When we believe there is a relationship between two things, we are likely to notice and recall instances that confirm our belief. If we believe that dreams are forecasts of actual events, we may notice and recall confirming instances more than disconfirming instances. The result is an illusory correlation.

Illusory correlations feed an illusion of control—that chance events are subject to our personal control. Gamblers, remembering their lucky rolls, may come to believe they can influence the roll of the dice by again throwing gently for low numbers and hard for high numbers. The illusion that uncontrollable events correlate with our actions is also fed by a statistical phenomenon called regression toward the mean. Average results are more typical than extreme results. Thus, after an unusual event, things tend to return toward their average level; extraordinary happenings tend to be followed by more ordinary ones.

The point may seem obvious, yet we regularly miss it: We sometimes attribute what may be a normal regression (the expected return to normal) to something we have done. Consider two examples:

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Failure to recognize regression is the source of many superstitions and of some ineffective practices as well. When day-to-day behavior has a large element of chance fluctuation, we may notice that others’ behavior improves (regresses toward average) after we criticize them for very bad performance, and that it worsens (regresses toward average) after we warmly praise them for an exceptionally fine performance. Ironically, then, regression toward the average can mislead us into feeling rewarded for having criticized others and into feeling punished for having praised them (Tversky & Kahneman, 1974).

“Once you become sensitized to it, you see regression everywhere.”

Psychologist Daniel Kahneman (1985)

The point to remember: When a fluctuating behavior returns to normal, there is no need to invent fancy explanations for why it does so. Regression toward the mean is probably at work.

RETRIEVAL PRACTICE

  • You hear the school basketball coach telling her friend that she rescued her team’s winning streak by yelling at the players after an unusually bad first half. What is another explanation of why the team’s performance improved?

The team’s poor performance was not their typical behavior. Their return to their normal—their winning streak—may just have been a case of regression toward the mean.

Correlation and Causation

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

Consider some recent newsworthy correlations:

What shall we make of these correlations? Do they indicate that students would achieve more if their parents would support them less? That stopping smoking would improve mental health? That abstaining from video games would make reckless teen drivers more responsible?

No, because such correlations do not come with built-in cause-effect arrows. But correlations do help us predict. An example: Parenthood is associated with happiness (Nelson et al., 2013, 2014). So, does having children make people happier? Not so fast, say researchers: Parents also are more likely to be married, and married people tend to be happier than the unmarried (Bhargava et al., 2014). Thus, the correlation between parenthood and happiness needn’t mean that parenting increases happiness.

RETRIEVAL PRACTICE

Correlation need not mean causation
  • Length of marriage positively correlates with hair loss in men. Does this mean that marriage causes men to lose their hair (or that balding men make better husbands)?

In this case, as in many others, a third factor can explain the correlation: Golden anniversaries and baldness both accompany aging.

Another example: Self-esteem correlates negatively with (and therefore predicts) depression. (The lower people’s self-esteem, the more they are at risk for depression.) So, does low self-esteem cause depression? If, based on the correlational evidence, you assume that it does, you have much company. A nearly irresistible thinking error is assuming that an association, sometimes presented as a correlation coefficient, proves causation. But no matter how strong the relationship, it does not. As FIGURE 1.5 indicates, we’d get the same negative correlation between self-esteem and depression if depression caused people to be down on themselves, or if some third factor—such as heredity or brain chemistry—caused both low self-esteem and depression.

Figure 1.5
Three possible cause-effect relationships People low in self-esteem are more likely to report depression than are those high in self-esteem. One possible explanation of this negative correlation is that a bad self-image causes depressed feelings. But, as the diagram indicates, other cause-effect relationships are possible.

This point is so important—so basic to thinking smarter with psychology—that it merits one more example. A survey of over 12,000 adolescents found that the more teens feel loved by their parents, the less likely they are to behave in unhealthy ways—having early sex, smoking, abusing alcohol and drugs, exhibiting violence (Resnick et al., 1997). “Adults have a powerful effect on their children’s behavior right through the high school years,” gushed an Associated Press (AP) story reporting the finding. But again, correlations come with no built-in cause-effect arrow. The AP could as well have reported, “Well-behaved teens feel their parents’ love and approval; out-of-bounds teens more often think their parents are disapproving jerks.”

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The point to remember (turn the volume up here): Correlation does not prove causation.3 Correlation indicates the possibility of a cause-effect relationship but does not prove such. Remember this principle and you will be wiser as you read and hear news of scientific studies.

Experimentation

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

Happy are they, remarked the Roman poet Virgil, “who have been able to perceive the causes of things.” How might psychologists perceive causes in correlational studies, such as the correlation between breast feeding and intelligence?

Researchers have found that the intelligence scores of children who were breast-fed as infants are somewhat higher than the scores of children who were bottle-fed (Angelsen et al., 2001; Mortensen et al., 2002; Quinn et al., 2001). Moreover, the longer they breast-feed, the higher their later IQ scores (Jedrychowski et al., 2012).

experiment a research method in which an investigator manipulates one or more factors (independent variables) to observe the effect on some behavior or mental process (the dependent variable). By random assignment of participants, the experimenter aims to control other relevant factors.

experimental group in an experiment, the group exposed to the treatment, that is, to one version of the independent variable.

What do such findings mean? Do smarter mothers have smarter children? (Breast-fed children tend to be healthier and higher achieving than other children. But their bottle-fed siblings, born and raised in the same families, tend to be similarly healthy and higher achieving [Colen & Ramey, 2014].) Or, as some researchers believe, do the nutrients of mother’s milk also contribute to brain development? To find answers to such questions—to isolate cause and effect—researchers can experiment. Experiments enable researchers to isolate the effects of one or more factors by (1) manipulating the factors of interest and (2) holding constant (“controlling”) other factors. To do so, they often create an experimental group, in which people receive the treatment, and a contrasting control group that does not receive the treatment. To minimize any preexisting differences between the two groups, researchers randomly assign people to the two conditions. Random assignment—whether with a random numbers table or flip of the coin—effectively equalizes the two groups. If one-third of the volunteers for an experiment can wiggle their ears, then about one-third of the people in each group will be ear wigglers. So, too, with ages, attitudes, and other characteristics, which will be similar in the experimental and control groups. Thus, if the groups differ at the experiment’s end, we can surmise that the treatment had an effect.

control group in an experiment, the group not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment.

random assignment assigning participants to experimental and control groups by chance, thus minimizing preexisting differences between the different groups.

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Recall that in a well-done survey, random sampling is important. In an experiment, random assignment is equally important.

To experiment with breast feeding, one research team randomly assigned some 17,000 Belarus newborns and their mothers either to a control group given normal pediatric care, or an experimental group that promoted breast feeding, thus increasing expectant mothers’ breast intentions (Kramer et al., 2008). At three months of age, 43 percent of the infants in the experimental group were being exclusively breast-fed, as were 6 percent in the control group. At age 6, when nearly 14,000 of the children were restudied, those who had been in the breast-feeding promotion group had intelligence test scores averaging six points higher than their control condition counterparts.

With parental permission, one British research team directly experimented with breast milk. They randomly assigned 424 hospitalized premature infants either to formula feedings or to breast-milk feedings (Lucas et al., 1992). Their finding: For premature infants’ developing intelligence, breast was best. On intelligence tests taken at age 8, those nourished with breast milk scored significantly higher than those who were formula-fed. Breast was best.

No single experiment is conclusive, of course. But randomly assigning participants to one feeding group or the other effectively eliminated all factors except nutrition. This supported the conclusion that for developing intelligence, breast is indeed best. If test performance changes when we vary infant nutrition, then we infer that nutrition matters.

The point to remember: Unlike correlational studies, which uncover naturally occurring relationships, an experiment manipulates a factor to determine its effect.

double-blind procedure an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo. Commonly used in drug-evaluation studies.

Consider, then, how we might assess therapeutic interventions. Our tendency to seek new remedies when we are ill or emotionally down can produce misleading testimonies. If three days into a cold we start taking vitamin C tablets and find our cold symptoms lessening, we may credit the pills rather than the cold naturally subsiding. In the 1700s, bloodletting seemed effective. People sometimes improved after the treatment; when they didn’t, the practitioner inferred the disease was too advanced to be reversed. So, whether or not a remedy is truly effective, enthusiastic users will probably endorse it. To determine its effect, we must control for other factors.

placebo effect [pluh-SEE-bo; Latin for “I shall please”] experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance or condition, which the recipient assumes is an active agent.

And that is precisely how new drugs and new methods of psychological therapy are evaluated (Chapter 16). Investigators randomly assign participants in these studies to research groups. One group receives a treatment (such as a medication). The other group receives a pseudotreatment—an inert placebo (perhaps a pill with no drug in it). The participants are often blind (uninformed) about what treatment, if any, they are receiving. If the study is using a double-blind procedure, neither the participants nor those who administer the drug and collect the data will know which group is receiving the treatment.

In double-blind studies, researchers check a treatment’s actual effects apart from the participants’ and the staff’s belief in its healing powers. Just thinking you are getting a treatment can boost your spirits, relax your body, and relieve your symptoms. This placebo effect is well documented in reducing pain, depression, and anxiety (Kirsch, 2010). Athletes have run faster when given a supposed performance-enhancing drug (McClung & Collins, 2007). Drinking decaf coffee has boosted vigor and alertness—for those who thought it had caffeine in it (Dawkins et al., 2011). People have felt better after receiving a phony mood-enhancing drug (Michael et al., 2012). And the more expensive the placebo, the more “real” it seems to us—a fake pill that costs $2.50 works better than one costing 10 cents (Waber et al., 2008). To know how effective a therapy really is, researchers must control for a possible placebo effect.

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RETRIEVAL PRACTICE

  • What measures do researchers use to prevent the placebo effect from confusing their results?

Research designed to prevent the placebo effect randomly assigns participants to an experimental group (which receives the real treatment) or to a control group (which receives a placebo). A comparison of the results will demonstrate whether the real treatment produces better results than belief in that treatment.

independent variable in an experiment, the factor that is manipulated; the variable whose effect is being studied.

confounding variable in an experiment, a factor other than the independent variable that might produce an effect.

dependent variable in an experiment, the outcome that is measured; the variable that may change when the independent variable is manipulated.

Independent and Dependent Variables

Here is an even more potent example: The drug Viagra was approved for use after 21 clinical trials. One trial was an experiment in which researchers randomly assigned 329 men with erectile disorder to either an experimental group (Viagra takers) or a control group (placebo takers given an identical-looking pill). The procedure was double-blind—neither the men nor the person giving them the pills knew what they were receiving. The result: At peak doses, 69 percent of Viagra-assisted attempts at intercourse were successful, compared with 22 percent for men receiving the placebo (Goldstein et al., 1998). For many, Viagra worked.

This simple experiment manipulated just one factor: the drug dosage (none versus peak dose). We call this experimental factor the independent variable because we can vary it independently of other factors, such as the men’s age, weight, and personality. Other factors, which can potentially influence the results of the experiment, are called confounding variables. Random assignment controls for possible confounding variables.

Experiments examine the effect of one or more independent variables on some measurable behavior, called the dependent variable because it can vary depending on what takes place during the experiment. Both variables are given precise operational definitions, which specify the procedures that manipulate the independent variable (the precise drug dosage and timing in this study) or measure the dependent variable (the questions that assessed the men’s responses). These definitions answer the “What do you mean?” question with a level of precision that enables others to repeat the study. (See FIGURE 1.6 for the British breast milk experiment’s design.)

Figure 1.6
Experimentation To discern causation, psychologists may randomly assign some participants to an experimental group, others to a control group. Measuring the dependent variable (intelligence score in later childhood) will determine the effect of the independent variable (type of milk).

To review and test your understanding of experimental methods and concepts, visit LaunchPad’s Concept Practice: The Language of Experiments, and the interactive PsychSim 6: Understanding Psychological Research.

Let’s pause to check your understanding using a simple psychology experiment: To test the effect of perceived ethnicity on the availability of a rental house, Adrian Carpusor and William Loges (2006) sent identically worded e-mail inquiries to 1115 Los Angeles–area landlords. The researchers varied the ethnic connotation of the sender’s name and tracked the percentage of positive replies (invitations to view the apartment in person). “Patrick McDougall,” “Said Al-Rahman,” and “Tyrell Jackson” received, respectively, 89 percent, 66 percent, and 56 percent invitations.

Experiments can also help us evaluate social programs. Do early childhood education programs boost impoverished children’s chances for success? What are the effects of different antismoking campaigns? Do school sex-education programs reduce teen pregnancies? To answer such questions, we can experiment: If an intervention is welcomed but resources are scarce, we could use a lottery to randomly assign some people (or regions) to experience the new program and others to a control condition. If later the two groups differ, the intervention’s effect will be supported (Passell, 1993).

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Let’s recap. A variable is anything that can vary (infant nutrition, intelligence, TV exposure—anything within the bounds of what is feasible and ethical). Experiments aim to manipulate an independent variable, measure a dependent variable, and control confounding variables. An experiment has at least two different conditions: an experimental condition and a comparison or control condition. Random assignment works to minimize preexisting differences between the groups before any treatment effects occur. In this way, an experiment tests the effect of at least one independent variable (what we manipulate) on at least one dependent variable (the outcome we measure). TABLE 1.3 compares the features of psychology’s research methods.

Table 1.3
Comparing Research Methods

RETRIEVAL PRACTICE

  • In the rental housing experiment, what was the independent variable? The dependent variable?

The independent variable, which the researchers manipulated, was the set of ethnically distinct names. The dependent variable, which they measured, was the positive response rate.

  • By using random assignment, researchers are able to control for ______________ ______________, which are other factors besides the independent variable(s) that may influence research results.

confounding variables

  • Match the term on the left with the description on the right.

1. double-blind procedurea. helps researchers generalize
from a small set of survey responses
to a larger population

2. random samplingb. helps minimize preexisting
differences between experimental
and control groups

3. random assignmentc. controls for the placebo
effect; neither researchers nor
participants know who receives
the real treatment

1. c, 2. a, 3. b

  • Why, when testing a new drug to control blood pressure, would we learn more about its effectiveness from giving it to half of the participants in a group of 1000 than to all 1000 participants?

We learn more about the drug’s effectiveness when we can compare the results of those who took the drug (the experimental group) with the results of those who did not (the control group). If we gave the drug to all 1000 participants, we would have no way of knowing whether the drug is serving as a placebo or is actually medically effective.

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Predicting Real Behavior

1-9 Can laboratory experiments illuminate everyday life?

When you see or hear about psychological research, do you ever wonder whether people’s behavior in the lab will predict their behavior in real life? Does detecting the blink of a faint red light in a dark room say anything useful about flying a plane at night? After viewing a violent, sexually explicit film, does an aroused man’s increased willingness to push buttons that he thinks will electrically shock a woman really say anything about whether violent pornography makes a man more likely to abuse a woman?

Before you answer, consider: The experimenter intends the laboratory environment to be a simplified reality—one that simulates and controls important features of everyday life. Just as a wind tunnel lets airplane designers re-create airflow forces under controlled conditions, a laboratory experiment lets psychologists re-create psychological forces under controlled conditions.

An experiment’s purpose is not to re-create the exact behaviors of everyday life but to test theoretical principles (Mook, 1983). In aggression studies, deciding whether to push a button that delivers a shock may not be the same as slapping someone in the face, but the principle is the same. It is the resulting principles—not the specific findings—that help explain everyday behaviors.

When psychologists apply laboratory research on aggression to actual violence, they are applying theoretical principles of aggressive behavior, principles they have refined through many experiments. Similarly, it is the principles of the visual system, developed from experiments in artificial settings (such as looking at red lights in the dark), that researchers apply to more complex behaviors such as night flying. And many investigations show that principles derived in the laboratory do typically generalize to the everyday world (Anderson et al., 1999).

The point to remember: Psychological science focuses less on particular behaviors than on seeking general principles that help explain many behaviors.

Question

2Ie5vqCAZaw2eGpwJN1x4hlsGT7GeFKaZYdSiZ0GgLC3eeDG11cwuGexgnM1D9kbr7xvnHXkzSV+QHAE9suFHasiF7KKDeXtS1n3Ux/wwPGJRpbvd/B2jj5+Jhjl9HJshEkS3wFIBYmiy5hUVOsJWO+hY9lON9hAKvU+zKfUbeCJE6PjnQFEjHySNrwQ0cyMqBvNNJqoUJhdOojmUVSJrh+ihkJnbvvlJuXwY/l3dF2ftpEo8aJcwf+OD+1aKjkIJ8pW7bEnZadzJb5Piw5J3a1ZhgVowddw5XuVgVpPW7OmgwRyvGD42NIFFYIvu7FCVVh1aG8Qjrvq1egn
Possible sample answer: In experimental studies, researchers choose one or more variables of interest and randomly assign people to a group in which that variable or variables is (are) present or one in which it is absent, keeping all other variables as similar as possible. In doing so, they can isolate the effect of the variable on the outcome of interest. In correlational research, two variables are also measured, but it is uncertain whether the degree of one variable caused the degree of the other or if a third (unknown) variable might be the reason for the relationship between the two variables of interest. Thus, correlational research can only describe the relationship between two variables, not whether one caused the other.

Psychology’s Research Ethics

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

We have reflected on how a scientific approach can restrain biases. We have seen how case studies, naturalistic observations, and surveys help us describe behavior. We have also noted that correlational studies assess the association between two factors, which indicates how well one thing predicts another. We have examined the logic that underlies experiments, which use control conditions and random assignment of participants to isolate the effects of an independent variable on a dependent variable.

Yet, even knowing this much, you may still be approaching psychology with a mixture of curiosity and apprehension. So before we plunge in, let’s entertain some common questions about psychology’s ethics and values.

Protecting Research Participants

Studying and protecting animals. Many psychologists study animals because they find them fascinating. They want to understand how different species learn, think, and behave. Psychologists also study animals to learn about people. We humans are not like animals; we are animals, sharing a common biology. Animal experiments have therefore led to treatments for human diseases—insulin for diabetes, vaccines to prevent polio and rabies, transplants to replace defective organs.

“Rats are very similar to humans except that they are not stupid enough to purchase lottery tickets.”

Dave Barry, July 2, 2002

Humans are complex. But the same processes by which we learn are present in rats, monkeys, and even sea slugs. The simplicity of the sea slug’s nervous system is precisely what makes it so revealing of the neural mechanisms of learning.

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Sharing such similarities, should we not respect our animal relatives? The animal protection movement protests the use of animals in psychological, biological, and medical research. “We cannot defend our scientific work with animals on the basis of the similarities between them and ourselves and then defend it morally on the basis of differences,” noted Roger Ulrich (1991).

Out of this heated debate, two issues emerge. The basic one is whether it is right to place the well-being of humans above that of other animals. In experiments on stress and cancer, is it right that mice get tumors in the hope that people might not? Should some monkeys be exposed to an HIV-like virus in the search for an AIDS vaccine? Is our use and consumption of other animals as natural as the behavior of carnivorous hawks, cats, and whales? The answers to such questions vary by culture. In Gallup surveys in Canada and the United States, about 60 percent of adults have deemed medical testing on animals “morally acceptable.” In Britain, only 37 percent have agreed (Mason, 2003).

Please do not forget those of us who suffer from incurable diseases or disabilities who hope for a cure through research that requires the use of animals.”

Psychologist Dennis Feeney (1987)

If we give human life first priority, what safeguards should protect the well-being of animals in research? One survey of animal researchers gave an answer. Some 98 percent supported government regulations protecting primates, dogs, and cats, and 74 percent supported regulations providing for the humane care of rats and mice (Plous & Herzog, 2000). Many professional associations and funding agencies already have such guidelines. Most universities screen research proposals, often through an animal care ethics committee, and laboratories are regulated and inspected. British Psychological Society (BPS) guidelines call for housing animals under reasonably natural living conditions, with companions for social animals (Lea, 2000). American Psychological Association (APA) guidelines state that researchers must ensure the “comfort, health, and humane treatment” of animals and minimize “infection, illness, and pain” (APA, 2002). The European Parliament mandates standards for animal care and housing (Vogel, 2010).

“The greatness of a nation can be judged by the way its animals are treated.”

Mahatma Gandhi, 1869–1948

Animal research benefiting animals Psychologists have helped zoos enrich animal environments (Weir, 2013). Thanks partly to research on the benefits of novelty, control, and stimulation, these gorillas are enjoying an improved quality of life in New York’s Bronx Zoo.

Animals have themselves benefited from animal research. One Ohio team of research psychologists measured stress hormone levels in samples of millions of dogs brought each year to animal shelters. They devised handling and stroking methods to reduce stress and ease the dogs’ transition to adoptive homes (Tuber et al., 1999). Other studies have helped improve care and management in animals’ natural habitats. By revealing our behavioral kinship with animals and the remarkable intelligence of chimpanzees, gorillas, and other animals, experiments have also led to increased empathy and protection for them. At its best, a psychology concerned for humans and sensitive to animals serves the welfare of both.

Studying and protecting humans. What about human participants? Does the image of white-coated scientists delivering electric shocks trouble you? Actually, most psychological studies are free of such stress. With people, blinking lights, flashing words, and pleasant social interactions are more common. Moreover, psychology’s experiments are mild compared with the stress and humiliation often inflicted by reality TV shows. In one episode of The Bachelor, a man dumped his new fiancée—on camera, at the producers’ request—for the woman who earlier had finished second (Collins, 2009).

informed consent giving potential participants enough information about a study to enable them to choose whether they wish to participate.

Occasionally, though, researchers do temporarily stress or deceive people, but only when they believe it is essential to a justifiable end, such as understanding and controlling violent behavior or studying mood swings. Some experiments won’t work if participants know everything beforehand. (Wanting to be helpful, the participants might try to confirm the researcher’s predictions.)

debriefing the postexperimental explanation of a study, including its purpose and any deceptions, to its participants.

The ethics codes of the APA and Britain’s BPS urge researchers to (1) obtain potential participants’ informed consent before the experiment, (2) protect them from harm and discomfort, (3) keep information about individual participants confidential, and (4) fully debrief people (explain the research afterward). University ethics committees use these guidelines to screen research proposals and safeguard participants’ well-being.

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Values in Research

Psychology is not value free. Values affect what we study, how we study it, and how we interpret results. Researchers’ values influence their choice of topics. Should we study worker productivity or worker morale? Sex discrimination or gender differences? Conformity or independence? Values can also color “the facts.” As we noted earlier, our preconceptions can bias our observations and interpretations; sometimes we see what we want or expect to see (FIGURE 1.7).

Figure 1.7
What do you see? Our expectations influence what we perceive. Did you see a duck or a rabbit? Show some friends this image with the rabbit photo covered up and see if they are more likely to perceive a duck instead. (Inspired by Shepard, 1990.)

Even the words we use to describe something can reflect our values. Are the sex acts we do not practice perversions or sexual variations? In psychology and in everyday speech, labels describe and labels evaluate: One person’s rigidity is another’s consistency. One person’s faith is another’s fanaticism. One country’s enhanced interrogation techniques, such as cold-water immersion, become torture when practiced by its enemies. Our labeling someone as firm or stubborn, careful or picky, discreet or secretive reveals our own attitudes.

Psychology speaks In making its historic 1954 school desegregation decision, the U.S. Supreme Court cited the expert testimony and research of psychologists Kenneth Clark and Mamie Phipps Clark (1947). The Clarks reported that, when given a choice between Black and White dolls, most African-American children chose the White doll, which seemingly indicated internalized anti-Black prejudice.

Popular applications of psychology also contain hidden values. If you defer to “professional” guidance about how to live—how to raise children, how to achieve self-fulfillment, what to do with sexual feelings, how to get ahead at work—you are accepting value-laden advice. A science of behavior and mental processes can help us reach our goals. But it cannot decide what those goals should be.

If some people see psychology as merely common sense, others have a different concern—that it is becoming dangerously powerful. Is it an accident that astronomy is the oldest science and psychology the youngest? To some, exploring the external universe seems far safer than exploring our own inner universe. Might psychology, they ask, be used to manipulate people?

Knowledge, like all power, can be used for good or evil. Nuclear power has been used to light up cities—and to demolish them. Persuasive power has been used to educate people—and to deceive them. Although psychology does have the power to deceive, its purpose is to enlighten. Every day, psychologists are exploring ways to enhance learning, creativity, and compassion. Psychology speaks to many of our world’s great problems—war, overpopulation, prejudice, family crises, crime—all of which involve attitudes and behaviors. Psychology also speaks to our deepest longings—for nourishment, for love, for happiness. Psychology cannot address all of life’s great questions, but it speaks to some mighty important ones.

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RETRIEVAL PRACTICE

  • How are animal and human research participants protected?

Animal protection legislation, laboratory regulation and inspection, and local ethics committees serve to protect animal and human welfare. At universities, Institutional Review Boards screen research proposals. Ethical principles developed by international psychological organizations urge researchers using human participants to obtain informed consent, to protect them from harm and discomfort, to treat their personal information confidentially, and to fully debrief all participants.