The Perfect Personality Test — Ignorance is Bliss

100% valid.

Let’s entertain the idea that a perfect personality test can exist. A test that can accurately quantify and measure a set of personality traits in an individual and consistently provide those same results when tested again. But even if this test can exist, should it?

So what exactly do I mean when I say ‘perfect’ personality test? I’ll operationalize it as having 1.00 validity and reliability. The test’s measurement is a perfect indicator of the ‘amount’ of trait in an individual, and that measurement is consistent across trials within the same subject. In short, the test perfectly measures the level of a trait as though it were tangible like a heartbeat. To be clear, if the test is perfectly reliable, that does not necessarily mean that the levels of something like neuroticism will not measure differently over time. Personality can change over time, and if it does, a reliable test would reflect those changes in its measurements.

How could this perfect test be applied? Primarily, to predict behavior or make decisions, either by the individuals tested or regarding them in some way. Additionally, some traits will always be more desired than others. This can have negative outcomes for those identified most with the less desirable traits. To illustrate this, I intend to borrow an example from pop culture.

Technically objective criteria.

The idea of a perfect personality test has been explored in novelist J.K. Rowling’s Harry Potter series. When magically inclined children enter the wizard school, Hogwarts, they are placed into one of four groups based on their levels of four personality traits. This is done with a test conducted by a magical ‘Sorting Hat’, which looks through the mind of its wearer to determine its personality. It is considered to accurately measure these characteristics with magic. These traits are bravery, cunning, loyalty and cleverness. Think of them as a magical counterpart to the “Big Five”. Whichever of the traits is the highest in a given student determines the group in which they are placed.

One of these groups, the “Slytherins” with the cunning trait, is associated with intolerant, criminal or otherwise undesirable, behavior that deviates from accepted norms in magical society. These individuals are told they are strongest in this characteristic and must behave appropriately. Not only that, they are taught to value that characteristic, it becomes part of their identities. Additionally, they are exposed primarily to others of their group, which could affect how some of the more moderate Slytherins develop their identities. Throughout the series there are examples of bad apples infecting the rest of the bunch. They have limited opportunities to alter their behavior, always exposed to the most negative environments.

While cunning itself is not inherently negative, there is a stigma that surrounds behaviors associated with it, and this very much parallels real life. Neuroticism for example, might be considered a less appealing trait than extraversion. It may be better not to divide at all, not to test at all, at least for the general population.