For our purposes, think of personality as the sum of ways in which an individual reacts to and interacts with others. We most often describe personality in terms of the measurable traits a person exhibits.

Early work on personality tried to identify and label enduring characteristics that describe an individual’s behavior including shy, aggressive, submissive, lazy, ambitious, loyal, and timid. When someone exhibits these characteristics in a large number of situations and they are relatively enduring over time, we call them personality traits.2 The more consistent the characteristic over time and the more frequently it occurs in diverse situations, the more important the trait is in describing the individual.

Personality assessments have been increasingly used in diverse organizational settings. In fact, 8 of the top 10 U.S. private companies and 57 percent of all large U.S. companies use them,3 including Xerox, McDonald’s, and Lowe’s.4 Schools such as DePaul University have also begun to use personality tests in their admissions process.5 Personality tests are useful in hiring decisions and help managers forecast who is best for a job.6

The most common means of measuring personality is through self-report surveys in which individuals evaluate themselves on a series of factors, such as “I worry a lot about the future.” In general, when people know their personality scores are going to be used for hiring decisions, they rate themselves as about half a standard deviation more conscientious and emotionally stable than if they are taking the test to learn more about themselves.7 Another problem is accuracy; for example, a candidate who is in a bad mood when taking a survey may very well receive inaccurate scores.

Research indicates our culture influences the way we rate ourselves. People in individualistic countries (see Chapter 4) like the United States and Australia trend toward self-enhancement, while people in collectivistic countries (see Chapter 4) like Taiwan, China, and South Korea trend toward self-diminishment. Self-enhancement does not appear to harm a person’s career in individualistic countries, but it does in collectivist countries, where humility is valued. Interestingly, underrating (self-diminishment) may harm a person’s career in both collectivistic and individualistic communities.8

Observer-ratings surveys provide an independent assessment of personality. Here, a coworker or another observer does the rating. Though the results of self-reports and observer-ratings surveys are strongly correlated, research suggests observer-ratings surveys predict job success more than self-ratings alone.9 However, each can tell us something unique about an individual’s behavior, so a combination of self-reports and observer-ratings predicts performance better than any one type of information. The implication is clear: Use both self-reports and observers-ratings (per SS) of personality when making important employment decisions.

An early debate centered on whether an individual’s personality is the result of heredity or environment. Personality appears to be a result of both; however, research tends to support the importance of heredity over environment. Heredity refers to factors determined at conception. Physical stature, facial features, gender, temperament, muscle composition and reflexes, energy level, and biological rhythms are either completely or substantially influenced by parentage—by your biological parents’ genetic, physiological, and inherent psychological makeup. The heredity approach argues that the ultimate explanation of an individual’s personality is the molecular structure of the genes, located on the chromosomes. This is not to suggest that personality never changes. For example, people’s scores on dependability tend to increase over time, as when young adults start families and establish careers. Personality is also more changeable in adolescence and more stable among adults.10 However, strong individual differences in dependability remain; everyone tends to change by about the same amount, so their rank order stays roughly the same.11