WRAPPING IT UP

SUMMARY

• Any characteristic pattern of behavior, thought, or emotional experience that exhibits relative consistency across time and situations is part of an individual’s personality. These patterns include personality traits as well as psychological attributes such as goals, moods, and strategies.

The Business of Testing

• Personality assessment is a frequent activity of industrial and clinical psychologists and researchers. Everybody also assesses the personalities of the people they know in daily life.
• Personality testing is a big business that can have important consequences. But some personality tests are useless or even fraudulent, so it is important to understand how they are constructed and how they are used.

Personality Tests

• An important issue for assessments, whether by psychologists or by laypeople, is the degree to which those assessments are correct. Do they correlate as expected with other assessments of related traits, and can they be used to predict behavior or important life outcomes?
• Some personality tests yield S data and others yield B data, but a more common distinction is between projective tests and objective tests. All projective tests yield B data; most but not all objective tests yield S data.
• Projective tests try to grant insight into personality by presenting participants with ambiguous stimuli and interpreting the participants’ open-ended responses. To the extent they are valid—and many are not—they appear to tap into aspects of personality not captured by questionnaire measures.
• The Rorschach test appears to have some degree of validity, but may not offer enough information beyond what can be gained from quicker, easier tests to justify its added expense. The Thematic Apperception Test (TAT) appears to measure aspects of needs (e.g., the need for achievement) that are missed by questionnaire measures.
• Objective tests ask participants specific questions and assess personality on the basis of the participants’ choices among predetermined options such as True or False, and Yes or No.
• Objective tests can be constructed by rational, factor analytic, or empirical methods; the state of the art is to combine all three methods.

Evaluating Assessment and Research

• The statistical significance of a result represents the probability that the data would have been obtained if the “null hypothesis” were true, but it is typically misinterpreted as yielding the probability that the substantive (non-null) hypothesis is true. Null-hypothesis significance testing (NHST) has many problems that are increasingly acknowledged. In particular, statistical significance is not the same as the strength or importance of the result.
• A better way to evaluate research than statistical significance is in terms of effect size, which describes numerically the degree to which one variable is related to another. One good measure of effect size is the correlation coefficient, which can be evaluated with the Binomial Effect Size Display (BESD).
• The dependability of a research finding can only be evaluated, ultimately, through replication. This issue came to a head in recent years when some prominent findings were found to not be as well established as psychologists had assumed. No single study can establish the truth of any result, which is why researchers need to repeat and extend findings and always be open to the implications of new data.

Ethical Issues

• Some people are uncomfortable with the practice of personality assessment because they see it as undignified or unfair. However, because people inevitably judge each other’s personalities, the real issue is whether personality assessment should be based on informal intuitions or formalized techniques.
• Research must be careful to do nothing to harm participants. Potentials for harm include subjecting people to traumatic experiences, deceiving them, or violating their privacy. The potential for the violation of individuals’ privacy is a particular important issue to be aware of for the future.
• Norms of “open science” encourage scientists to fully report all of their research methods and findings, including studies that fail to find the expected or hoped-for result, and to share their data with other scientists.

Conclusion

• As a citizen, it is important to keep close watch on the activities of schools, police departments, doctors, businesses, governments, and, yes, scientists.

KEY TERMS

objective test, p. 76

factor analysis, p. 81

p-level, p. 86

Type I error, p. 88

Type II error, p. 88

effect size, p. 88

correlation coefficient, p. 89

Binomial Effect Size Display (BESD), p. 91

replication, p. 93

publication bias, p. 94

questionable research practices (QRP’s), p. 94

p-hacking, p. 94

open science, p. 102

THINK ABOUT IT

1. If you wanted to understand someone’s personality and could ask the person only three questions, what would those questions be? What would the answers reveal?
2. How would you choose someone to be your roommate? Your employee? A date? Would personality traits be relevant to your choice? How would you evaluate those traits?
3. Have you ever taken a personality test? Did the results seem accurate? Were the results useful? Did they tell you anything you did not already know?
4. How many uses can you think of for knowing someone’s scores on the MMPI? Are any of these uses unethical?
5. If you were being considered for a job you badly wanted, would you prefer the decision to be based on a personality test score or the employer’s subjective judgment of you?
6. If you have taken a statistics course, what does a significance level tell you? What does it not tell you? If we were to stop using significance levels to evaluate research findings, what could we use instead?
7. Let’s say we find that you score 4 points higher on a “conscientiousness” test than another person. Alternatively, imagine that women score 4 points higher on the same test, on average, than men do. In either case, is this difference important? What else would we have to know to be able to answer this question?
8. Is deception in psychological research justified? Does it depend on the research question? Does it depend on the specific kind of deception? Does it depend on the kind of informed consent offered by the research participant? Who, if anybody, is harmed by the use of deception in research?
9. Some psychologists research differences between races in intelligence. Let’s say members of one race really do have higher IQ scores than members of another race. Consider: Is this the kind of research psychologists should be doing, or is the issue better left alone? Once the research is done, how will the results be used?
10. Repeat question 9, but substitute gender for race.
11. If you found out that the person you had just been talking to was a participant in a research study, and that your own speech and actions had been recorded, would that bother you? Do you think your permission should have been required first?
12. Scientist A manufactures fake data that support his theory and publishes them in a major journal. Scientist B does three studies; two fail to support his theory and one confirms it. He decides only to publish the confirming study. Whose actions harm science more, Scientist A or Scientist B, or are they the same?
13. A scientist works hard to complete a study that includes a lot of difficult-to-obtain data. After she publishes her findings, another scientist says, “I think you maybe analyzed your data wrong. Please show me your data.” The first scientist replies, “The data are mine and I worked hard for them. Get your own data.” Does she have a point? Can you think of any circumstances in which scientists should not be required to share their data publicly?
14. Scientists often do things that nonscientists do not really understand. How can society make sure that science is used for good rather than evil purposes?

SUGGESTED RESOURCES

Online

Center for Open Science

The Center for Open Science provides many resources to make it easier to do good science. It is where a researcher can “pre-register” a study (state the predictions and planned analyses for a study before it begins), share and access data from other researchers, and share articles that have not been published yet. The website is cos.io.

Society for the Improvement of Psychological Science

This new society, founded in 2016, is already growing to be a major force in psychology. Its purpose is to develop and advocate for improved methods and practices. It holds annual meetings, and its website is improvingpsych.org.

Correlation Calculator

There are many easy ways to calculate a correlation coefficient. This calculator is one of many available online: https://www.socscistatistics.com/tests/pearson/

Philosophy of Psychology Lectures

The late Paul Meehl, a long-time professor at the University of Minnesota, is probably the most respected methodologist in the history of personality psychology. His ideas about how to connect data with theory provide keen insights into modern controversies, such as issues of replicability and open science, discussed in this chapter. Lectures he gave in one of his graduate-level courses are available online. Although the course is called “Philosophy of Psychology,” as he points out in the first lecture the content is really the philosophy of how to do research in psychology (and other fields). You can watch and listen for free at: meehl.umn.edu/recordings/philosophical-psychology-1989

Print

Cumming, G. (2012). Cumming, G. (2012). Understanding the new statistics: Effect sizes, confidence intervals and meta-analysis. New York: Taylor & Francis.

The most important of a new generation of statistics textbooks that go beyond conventional null hypothesis significance testing to teach alternative methods for estimating effect sizes and confidence intervals, and cumulating research results over many studies. I expect that the way statistics is taught will change dramatically in the next few years; this book is leading the way. A lot of recent, interesting information on the “new statistics” is available at Cummings’ website: thenewstatistics.com/itns.

Wiggins, J. S. (1973). Personality and prediction: Principles of personality assessment. Reading, MA: Addison-Wesley.

The classic textbook for personality psychologists, including material of methodological as well as substantive interest. The book is now slightly out of date, but like a true classic, has maintained its interest and value with age.

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