Personality tests like the Minnesota Multiphasic Personality Inventory and others are used to find out what a person is like, internally. They measure reactions to certain situations, look at circumstances, choices and other factors to determine if someone is extroverted or introverted, active or passive, and what drives them to make the decisions they do. Other ways of learning what a person is like include some less than scientific methods, such as the time and place of birth, the alignment of the planets on their birthday and even the numbers in their age, birth month, and day. But is any of it even valid? The short answer? No, not really.
Carl Jung was a pioneer in the field of psychology and came up with four spectrums; thinking, feeling, sensation, and intuition and posited that where a person landed in these areas determines the kind of person they are. This was the basis for the Myers-Briggs type indicator, which lists eight personality traits, in pairs, or sixteen possible personality types. While it’s a very well-known tool in psychology, one study showed that it’s not always scientifically sound, because 50% of those who took the test and were classified as one type, were classified as a different type when re-taking the test 5 weeks later. The analysis also is not good at predicting how well a potential job candidate would do in a particular role, what behavior choices a person might make in a given situation, and how they behave in relationships.
The most reliable indicator of personality looks at five characteristics: openness, conscientiousness, extroversion, agreeableness, and neuroticism. Looking at these five traits has shown the best results in predicting behavior in relationships or jobs. The science of personality is a unique area in neuroscience research, and each way of looking at our traits has to measured for its scientific value.