Types and Traits

There are two types of people in the world: those who believe there are two types of people in the world and those who don't. I'm the second type.

In fact, increasingly, I'm wondering how much value there is in the whole "personality type" idea full stop, where people of different personality types are viewed as qualitatively different from each other (apples versus oranges).

The idea of personality types jives pretty strongly with our lay understanding of personality, hence the popularity of Cosmo magazine's - or these days, Facebook's - "What kind of sex maven are you?" type personality tests that categorize women as "bad girls," "romantics," "sensualists," etc. These typologies also offer rich descriptions of a person (e.g. the Myers-Briggs categories, sun signs).

But does thinking of people as different types tell us more about a person than does thinking of people in terms of their personality traits - dimensions like authoritarianism, conscientiousness, or self-monitoring along which people differ quantitatively? In other words, do we gain more understanding by knowing that a person is Type W rather than knowing that the person is high or low on traits X, Y, and Z? Do particular combinations of traits X, Y, and Z yield emergent attributes or behaviors that we would not typically see?

I would have suspected yes, but apparently the answer is mostly no.

Personality psychologist David Funder writes: "The latest evidence indicates that knowing a person's personality type adds nothing to the ability to predict his or her behavior, beyond what can be done using the traits that define the typology" (The Personality Puzzle, p. 213). My professor says that finding interactions among traits (e.g. that trait A is linked to an outcome based on the person's level of trait B) is rare. This suggests that in general, the degree of association of a trait with a behavior is not dependent on where the person stands on other traits. For example, the trait of conscientiousness has been positively linked with academic success (and a host of other good outcomes). Based on this reasoning, we should predict that high conscientiousness will be equally associated with academic success regardless of the person's IQ, emotional stability, etc.

One thing that I like about the trait approach (aside from its empirical support) is that it does seem right to conceptualize many aspects of personality as separate dimensions along which people can vary rather than aspects that separate people into groups. For example, would it really make sense to separate people into the "Creative" type versus the "Logical" type (which I think is a fairly common thing for people to do)? There are plenty of people who are high on both or, more sadly, low on both.

That being said, some people (strong situationists) would argue that personality traits don't tell us that much about people either because an individual's behavior is inconsistent and much more driven by the situation / environment than it is by some inherent personal characteristics that are claimed to be enduring over time. While it's well-established that people do over-attribute behavior to the characteristics of the person rather than the situation (the fundamental attribution error), it seems implausible that we could predict or explain behavior very well by ignoring personality entirely, barring possible particular situations in which individual differences in personality would be overwhelmed by a strong environmental stimulus.