Many of my clients ask me whether I use standardized tests to help determine strengths, weaknesses, interests, and personality types. They have read that not only can those kinds of tests be useful in choosing a career, but that they can also to some degree predict the likelihood of success in a chosen field. In this post I’m going to explore that notion.

Personality testing is exemplified by Myers-Briggs, a personality test extrapolated from the famous psychologist Carl Jung’s classification of personality types in the 1920s. The test was initially developed during World War II, and sprang out of the belief that it could help women, entering the workplace for the first time, identify jobs in which they could be most effective. It classified personality into 16 types, indicated by 4 letters.

Myers-Briggs may indeed be a valuable tool for large organizations that hire thousands of people (corporations, the military, governments). They have a strong interest in maximizing worker productivity and minimizing employee turnover. So, if (based on past experience with a large number of employees) they have discovered that an ENTP is 12% more likely to succeed in a particular role than is an ISFJ, it might well be beneficial for them to include personality testing as part of the qualification process.

For an individual, however, the value of the Myers-Briggs classification is far more dubious. For one thing, there is a large degree of variability in test results over time, with some studies showing that up to 75% of people will wind up being classified as a different personality type when they re-take the test a year later. Secondly, the Myers-Briggs personality types are far too broad to give much specific career guidance. For example, research based on Myers-Briggs indicates that an ISFJ, the most common personality type, is well suited for such careers as nurse, teacher, market researcher, secretary, and assistant. These are exactly the same jobs at which ESFJs are supposed to excel.

Third, I have a real concern about the degree to which personality testing becomes self-fulfilling. This phenomenon is apparent in a more popular, better-known sphere: astrology. Astrology buffs view their personalities through one of twelve lenses (the twelve signs of the zodiac), focusing on the traits that are supposedly characteristic of their sign (ambiguous Libra, vain Leo, independent Scorpio, etc.). To the degree that people are aware of the traits embodied by their sign, and believe in the accuracy of astrology, they are far more likely to notice consonant, as opposed to dissonant, evidence. The same is true with a personality test. Some of my clients who have taken Myers-Briggs give it so much authority that they allow it to overrule their own life experience. For example, I recently had a client relate that he never knew he was an introvert until he took the test! As we explored the issue he cited example after example of extroverted behavior, until he finally began to wonder how much faith to put in a test that suggested he was something he was not (or at least might not be).

You yourself are far more likely to be an accurate judge of your outstanding personality characteristics than is a standardized test. If you have questions about a particular aspect of your personality that might apply to career choice (e.g., am I really a risk-taker?), ask your family and friends. I believe that you’ll get a much more accurate, and certainly more nuanced, answer than you will from a personality test.