Personality Assessment: A Look Behind the Façade

Personality assessment is one of the most fascinating topics in psychology. It is about finding out who we really are, what drives us, and how we behave in different situations. But how can something as complex as personality be measured? In this blog post, I will give you an overview of how personality assessment works, what methods are available, and how they are used in practice.

What is personality assessment?

Personality assessment deals with measuring and assessing stable personality traits. While performance assessment often focuses on measurable abilities such as intelligence or concentration, personality assessment focuses on stable patterns of thinking, feeling, and behavior that characterize a person over longer periods of time. These traits can include characteristics such as extraversion, neuroticism, or conscientiousness.

Personality assessment can be conducted using various methods, including:

  1. Self-report methods such as questionnaires
  2. Other-report methods, in which other people assess the person being tested
  3. Projective methods, in which the person being tested responds to ambiguous stimuli intended to reveal unconscious motives

According to the book by Rentzsch and Schütz (Chapter 3.3, pages 77–82), all these methods are designed to capture stable personality traits. Let’s take a closer look at the most important methods.

Methods of personality assessment

Self-report methods

The best-known method of personality assessment is probably self-report methods, in which the test taker answers questions about their own behavior and experiences. One example is the NEO Five-Factor Inventory (NEO-FFI), which measures the five major personality factors: extraversion, neuroticism, openness to experience, agreeableness, and conscientiousness.

These methods involve standardized questionnaires in which the test taker rates statements such as “I enjoy speaking in front of a group of people” on a scale ranging from “strongly disagree” to “strongly agree.” The answers are then used to create a personality profile.

Example: NEO-FFI

Let’s assume you want to find out how extraverted you are. In a questionnaire such as the NEO-FFI, you would respond to statements like “I enjoy being the center of attention.” Your answers to these questions would then be combined into a score indicating where you stand in terms of extraversion compared with the norm group.

These self-report methods have the advantage of being relatively easy to administer and evaluate. They are also highly standardized, which increases their reliability.

Informant-report methods

Other-report methods complement self-reports. Here, other people—for example, friends, colleagues, or family members—are asked to describe the test taker’s personality. These methods are particularly useful when you want to find out how a person is perceived by those around them.

The advantage of other-reports is that they offer a different perspective on a person’s personality. While a self-report is based on one’s own perception, other-reports provide insight into how the person behaves in social contexts.

Projective methods

Projective methods are a completely different approach to personality assessment. In these tests, the test taker is shown ambiguous stimuli and asked to respond freely to them. A classic example is the Rorschach test, in which people are shown inkblot images and asked to describe what they see in them. The idea is that people “project” their unconscious thoughts and feelings onto these images.

Projective methods are often used in clinical psychology to capture deeper, often unconscious aspects of personality. However, they are also controversial because their objectivity and reliability are lower than those of standardized questionnaires.

Norm-referenced vs. criterion-referenced assessment

In personality assessment, test results are generally evaluated using either a norm-referenced or a criterion-referenced approach.

  • In norm-referenced assessment, a person’s test result is compared with the results of a norm group. One example would be a personality test that tells you whether you are more extraverted than the majority of the population.
  • In criterion-referenced assessment, the test result is not compared with a norm group. Instead, specific criteria or thresholds are established in order to draw a conclusion. This method is particularly useful in clinical assessment for determining whether a person shows, for example, a clinically significant level of neuroticism.

Example: Norm-referenced personality assessment

Imagine taking a test that measures your conscientiousness. Your result is compared with the results of 1,000 other people who took the same test. You find out that you are among the 20% with the highest levels of conscientiousness. This is a typical example of norm-referenced assessment, in which your test result is interpreted in comparison with a large normative sample.

Faking and reactivity

A central problem in personality assessment is faking. Since most tests are based on self-descriptions, people may present their answers in an overly favorable light, especially in contexts such as personnel selection, where a good test result could lead to a job offer.

Another problem is reactivity, which means that people change their behavior when they know they are being tested. As a result, test findings may not reflect the person’s actual behavior.

Example calculations in R

For personality assessment, questionnaires are frequently used to represent different dimensions (e.g., the Big Five personality factors) using scale scores. Here is an example of how you can analyze personality questionnaire data in R.

RCopy code# Assume we have a data series of NEO-FFI scores for extraversion
extraversion_scores <- c(45, 52, 48, 60, 55, 63, 49, 57, 54, 62)

# Calculate the mean and standard deviation
mean_extraversion <- mean(extraversion_scores)
sd_extraversion <- sd(extraversion_scores)

# Output
cat("The mean of the extraversion scores is:", mean_extraversion, "
")
cat("The standard deviation of the extraversion scores is:", sd_extraversion, "
")

The script shows you how to calculate the mean and standard deviation of the extraversion scores. Calculations like these help you better understand and contextualize personality assessment data.

Conclusion

Personality assessment offers a fascinating insight into the human psyche. Whether through self-reports, informant reports, or projective techniques, these methods help us identify the stable characteristics of a person that distinguish them over long periods of time. When interpreting test results, it is important to always keep the context in mind and be aware of possible distortions caused by deliberate misrepresentation or reactivity.

With standardized tests and modern statistical methods such as data analysis in R, we can now measure and evaluate personality traits at a high scientific standard. However, there is always some residual uncertainty—for after all, a person’s personality cannot always be easily captured in numbers.