How Personality Tests Work

The principle behind personality questionnaires is that it is possible to quantify your intrinsic personality characteristics by asking you about your feelings, thoughts and behavior. You will be presented with statements describing various ways of feeling or acting and asked to answer each one on a 2 point, 5 point or 7 point scale. For example;

The number of questions you are expected to answer varies from about 50 to 200, depending on the duration of the test. At first glance, these tests may seem to be both simplistic in their approach and unrealistic in their aims. After all, how can something as complex as your personality be measured and quantified in so little time and with so few questions. In addition, it is easy to see that some of the questions are imprecise and could be answered honestly in different ways depending on your particular interpretation of them on the day.

For example, take question 3 above 'I am good at dealing with difficult people? Your answer to this question depends on your interpretation of two things. Firstly 'good', does this mean good compared to other people in your office, good compared to the general public or good compared to some other group? Secondly 'difficult people', does this mean people who are abusive and violent, people who are withdrawn, people who are selfish or what?

The important point to remember is that even the best of the personality questionnaires used in selection are far from perfect. They are seriously constrained because the number of questions is limited by the time available - the personality questionnaire is usually only one of a battery of tests, interviews and other exercises that make up the selection process. However, even if we accept that these tests do have some shortcomings, we still need to know what they are trying to measure and why.

“The particular pattern of behavior and thinking that prevails across time and contexts, and differentiates one person from another.”

The goal of psychologists is to understand the causes of individual differences in behavior. In order to do this one must firstly identify personality characteristics (often called personality traits), and then determine the variables that produce and control them.

A personality trait is assumed to be some enduring characteristic that is relatively constant as opposed to the present temperament of that person which is not necessarily a stable characteristic. Consequently, trait theories are specifically focused on explaining the more permanent personality characteristics that differentiate one individual from another. For example, things like being; dependable, trustworthy, friendly, cheerful, etc.

One of the first trait theories was developed in ancient Greece by the physician Galen who suggested that our personality was a reflection of the four humors (fluids) that were important in the human body.

Personality Type	Person is…	Associated Humor
Choleric	bad tempered, irritable	Yellow Bile
Melancholic	gloomy, pessimistic	Black Bile
Phlegmatic	sluggish, non-excitable	Phlegm
Sanguine	cheerful, passionate	Blood

If one of these humors dominated the others then the personality type associated with that humor would be observed. The kind of strict categorization suggested by theories like Galen’s suggests that there very different types of personalities.

More recently, personality theories have leaned more towards the idea that we all have similar personality traits or characteristics, but the extent to which we possess that trait differs. For example, we often classify people as tall or short, but we don’t really think that people must be either one or the other. We understand that height is a trait the some of us have more of than others, but we all have it to some extent. If we accept the existence of common personality traits that we all have to varying extents, then the next stage is to agree on how to define them.

Personality Tests > How They Work