WRAPPING IT UP
SUMMARY
Psychology’s Emphasis on Method
- Psychology emphasizes the methods by which knowledge can be obtained. Knowledge about methods is necessary for conducting research, and also for understanding the results of research done by others.
- Science is the seeking of new knowledge, not the cataloging of facts already known. Technical training conveys current knowledge about a subject, so that the knowledge can be applied. Scientific education, by contrast, teaches not only what is known but also how to find out what is not yet known.
- In order to study personality, first you must look at it: All science begins with observation. The observations a scientist makes and expresses as numbers are data.
- For the scientific study of personality, four types of data are available. Each type has advantages and disadvantages.
- S (self-judgment) data comprise a person’s assessments of his own personality. The advantages of S data are that each individual has (in principle) a large amount of information about himself; that each individual has unique access to his own thoughts, feelings, and intentions; that some kinds of S data are true by definition (e.g., self-esteem); that S data also have a causal force all their own; and that S data are simple and easy to gather. The disadvantages are that people sometimes make errors or have biases in self-reports, and that S data may be so easy to obtain that psychologists rely on them too much.
- I (informant) data comprise the judgments of knowledgeable acquaintances about the personality traits of the person being studied. The advantages of I data are that there is a large amount of information on which informants’ judgments are potentially based; that this information comes from real life; that informants can use common sense; that some kinds of I data are true by definition (e.g., likeability); and that the judgments of people who know the person are important because they affect reputation, opportunities, and expectancies. The disadvantages of I data are that no informant knows everything about another person; that informants’ judgments can be subject to random errors, such as forgetting; and that judgments can be systematically biased.
- L (life) data comprise observable life outcomes, such as being arrested, getting sick, or graduating from college. L data have the advantages of being objective and verifiable, as well as being intrinsically important and potentially psychologically relevant, but they have the disadvantages of being determined by many different factors, and sometimes are not even psychologically relevant.
- B (behavioral) data comprise direct observations of a person doing something. Behavior may be observed in the person’s real-life environment or an artificial setting constructed in a psychological laboratory. Behaviors can include words spoken, actions performed, and even physiological responses. The advantages of B data are that they can tap into many different kinds of behaviors, including those that might not occur or be easily measured in normal life; and that they are obtained through direct observation, and so are, in that sense, objective. B data have two disadvantages. First, they are difficult and expensive to gather. Second, for all their superficial objectivity, it is still not always clear what they mean psychologically.
- The essence of science is that conclusions should be based on data. Data can vary widely in quality; in personality psychology, the important dimensions of data quality are reliability, validity, and generalizability.
- Reliability refers to the stability or repeatability of measurements. Validity refers to the degree to which a measurement actually measures what it is trying to measure. Generalizability is a broader concept that subsumes both reliability and validity, and refers to the kinds of other measurements to which a given measurement is related.
- The plan one uses for gathering psychological data is the research design. The three main methods are case, experimental, and correlational.
- Case studies examine particular phenomena or individuals in detail, and can be an important source of new ideas. To test these ideas, correlational and experimental studies are necessary. Each of the three methods has advantages and disadvantages, but the experimental method is the only one that can be used to determine causality.
KEY TERMS
THINK ABOUT IT
- If you wanted to know all about the personality of the person sitting next to you, what would you do?
- In your opinion, is there anything about another person that is impossible to know? Is there anything that is unethical to know?
- To assess the degree that someone is “sociable” would seem easy to do using S data or I data. How might you assess this trait using L data or B data?
- Can you think of kinds of observations—data—that you could gather about a person that would fall outside of the BLIS scheme? Which of the four categories comes closest to describing these data?
- An experimenter gives a subject a set of 10 impossible-to-solve mathematical problems. The experimenter times how long the subject works on the problems before giving up on the task. The minutes-and-seconds measure the experimenter has taken is, of course, B data. The experimenter calls this measure “a real, behavioral measure of persistence.” What is right and wrong about this label?
- People sometimes describe themselves differently than they are described by others (a discrepancy between S data and I data), and they sometimes describe themselves differently from how they act (a discrepancy between S data and B data). Why might this happen? When these kinds of data disagree with each other, which would you tend to believe?
- Are some kinds of data “privileged” for some kinds of questions? For example, if a person says he is happy (S data), but his acquaintances say he is unhappy (I data), is it possible that the I data could be more valid than the S data? Would it be meaningful to say something like, “He’s not as happy as he thinks he is”?
- If an attribute like “happiness” can most appropriately (or only) be assessed with S data, are there other attributes of personality best (or only) assessable via I data, L data, or B data?
- Is research done with the predominantly white college students in Western cultures also relevant to members of ethnic minorities or to people who live in other cultures? In what areas would you expect to find the most differences?
- If you wanted to do research on how alcohol use affects health, would you do experimental studies or correlational studies? What could each kind of study tell you? What would each kind of study not be able to tell you? What kinds of studies would be feasible or ethical?
SUGGESTED RESOURCES
American Psychological Association (2010). Publication Manual of the American Psychological Association (6th ed.). Washington, DC: American Psychological Association.
This sets the standards that must be followed for all articles in journals published by the American Psychological Association, and most other psychological journals also follow it. The book is full of information and advice on the proper conduct, analysis, and reporting of psychological research. Every aspiring psychologist should have a copy. While the book is not available for free (the Manual is an important source of revenue for APA), a lot of useful and updated information is available, without cost, at www.apastyle.org/manual.
Cronbach, L. J., & Meehl, P. E. (1955). Construct validity in psychological tests. Psychological Bulletin, 52, 281–302.
A difficult read, but the classic presentation of how personality psychologists think about the validity of their measurements. One of the most influential methodological articles ever published.
Rosenthal, R., & Rosnow, R. L. (2007). Essentials of behavioral research: Methods and data analysis (3rd ed.). New York: McGraw-Hill.
One of the best primers for a beginning researcher. This book includes many topics (such as effect size) not handled well in other methods or statistics texts. You will have to read this book to see what its authors mean by the advice “Think Yiddish, write British.”
Want to earn a better grade on your test? Go to INQUIZITIVE to learn and review this chapter’s content, with personalized feedback along the way.
Glossary
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Exploration of the unknown; finding out something that nobody knew before one discovered it.
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There are no perfect indicators of personality; there are only clues, and clues are always ambiguous.
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Something beats nothing, two times out of three.
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Self-judgments, or ratings that people provide of their own personality attributes or behavior.
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The degree to which an assessment instrument, such as a questionnaire, on its face appears to measure what it is intended to measure. For example, a face-valid measure of sociability might ask about attendance at parties.
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The process by which people try to bring others to treat them in a manner that confirms their self-conceptions.
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Informants’ data, or judgments made by knowledgeable informants about general attributes of an individual’s personality.
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Data that derive, in the final analysis, from someone using his or her common sense and observations to rate personality or behavior.
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The tendency for someone to become the kind of person others expect him or her to be; also known as a self-fulfilling prophecy and behavioral confirmation.
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The self-fulfilling prophecy tendency for a person to become the kind of person others expect him or her to be; also called the expectancy effect.
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Life data, or more-or-less easily verifiable, concrete, real-life outcomes, which are of possible psychological significance.
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Behavioral data, or direct observations of another’s behavior that are translated directly or nearly directly into numerical form. B data can be gathered in natural or contrived (experimental) settings.
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In measurement, the tendency of an instrument to provide the same comparative information on repeated occasions.
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The variation of a number around its true mean due to uncontrolled, essentially random influences; also called error variance.
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A temporary psychological event, such as an emotion, thought, or perception.
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A relatively stable and long-lasting attribute of personality.
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The combining together of different measurements, such as by averaging them.
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In psychometrics, a mathematical formula that predicts the degree to which the reliability of a test can be improved by adding more items.
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The technology of psychological measurement.
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The degree to which a measurement actually reflects what it is intended to measure.
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An idea about a psychological attribute that goes beyond what might be assessed through any particular method of assessment.
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The strategy of establishing the validity of a measure by comparing it with a wide range of other measures.
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The degree to which a measurement can be found under diverse circumstances, such as time, context, participant population, and so on. In modern psychometrics, this term includes both reliability and validity.
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Studying a particular phenomenon or individual in depth both to understand the particular case and to discover general lessons or scientific laws.
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A research technique that establishes the causal relationship between an independent variable (x) and dependent variable (y) by randomly assigning participants to experimental groups characterized by differing levels of x, and measuring the average behavior (y) that results in each group.
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A research technique that establishes the relationship (not necessarily causal) between two variables, traditionally denoted x and y, by measuring both variables in a sample of participants.
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A diagram that shows the relationship between two variables by displaying points on a two-dimensional plot. Usually the two variables are denoted x and y, each point represents a pair of scores, and the x variable is plotted on the horizontal axis while the y variable is plotted on the vertical axis.
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A number between –1 and +1 that reflects the degree to which one variable, traditionally called y, is a linear function of another, traditionally called x. A negative correlation means that as x goes up, y goes down; a positive correlation means that as x goes up, so does y; a zero correlation means that x and y are unrelated.