Why Personality isn’t Simple: The Case of Extraversion and Sales Performance

Although using personality tests for hiring is common, using them well probably isn’t.

When people see a candidate’s personality traits (or meet a candidate for an interview), we often choose a few traits we imagine to be important for the job and focus only on those.  On its face, this seems like a sensible approach: Only focus on what “matters.”  The problem is that in practice things are rarely this simple.  Human psychology is complex and dynamic, to the point where even very obvious relationships—if examined in isolation—are often weak.  Furthermore, when it comes to things like personality and job performance, even our strongest intuitions are not always correct about which traits really matter to begin with.

Consider the case of extraversion and sales performance.

Popular wisdom says better sales reps should be extraverts: After all extraverts like interacting with people, something one does quite a lot of in sales.  The problem?  In practice, extraversion is only weakly—if at all—related to sales success.  This is a result we’ve seen over and over again in our own data, and also one well noted in the literature.  A highly cited meta-analysis of personality and job performance (Hurtz & Donovan, 2000) places the true correlation between extraversion and sales performance at only r =.15, suggesting that extraversion explains only a paltry 2.25% of sales success.

Why might this be?  Well, there are a few possibilities.  One recent article published in Psychological Science argues that the relationship between extraversion and sales performance isn’t a straight line like we often imagine, but rather an inverted u-shaped curve (Grant, 2013):

sales extroversion graphs v2

In other words, it may be neither introverts nor extraverts who make the best sales reps, but rather those who are in the center.  These so called “ambiverts” may come off as assertive and enthusiastic, but not too assertive, overconfident, or inattentive.

Another way to think of results of this sort is that as with many traits people can be introverted (or extraverted) in different ways.  For example at a recent psychology conference I saw a poster in which researchers at Wellesley and Swarthmore Colleges (Grimes, Cheek, Cheek & Norem. 2013) argued that there are not one but several kinds of introversion.  Some kinds of introversion related to subclinical expressions of psychological disorders (alexithymia, autism spectrum, schizotypy) whereas others decidedly did not.  This is compelling stuff.  When hiring sales reps, I bet few of us stop and think “This person seems introverted, but what kind of introvert is he?”  Yet it’s very plausible that different brands of introversion or extraversion could have different outcomes in a sales situation.

All these issues merit further research.  However, one thing we can say for sure: If you only hire extraverts for sales positions, you’re probably missing out on some star performers.

Personality’s just not that simple.

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