Our recent post on the trouble with introverts struck a chord with many readers. So in our on-going series of seeing which personality types have the upper hand at work – (see Night Owls vs. Early Birds) – let’s see how introverts fare against their more outgoing cohorts.

People who are extroverts naturally have an easier time interacting with other people, conversing with strangers and promoting themselves. That would seem to give them an advantage in the career essentials of job interviewing and networking.

Extroverts also tend to step into more public-facing roles such as in sales, public relations and human resources. Introverts lean more towards behind-the-scene roles like writing, programming and accounting.

So far, advantage extrovert. With higher-profile jobs, better job interviewing skills and the ability to effortlessly interact and self-promote, the more outgoing people will have an easier time landing jobs and moving up the ranks.

However, a study from Professor Adam M. Grant at the University of Pennsylvania shows that when it comes to earning potential, extroverts aren’t the clear winners. [Opens as a PDF.]

For this study, researchers tested the personalities of 340 sales representatives, ranking their level of introversion or extroversion. The reps were positioned on a seven-point scale, with one being the most introverted and seven being the most extroverted.

When their performance was calculated over the course of the study, introverts actually did perform the worst, earning an average of $120 an hour. Extroverts had slightly greater success with revenues averaging $125 per hour.

However, the top performers were those people from a third group that Professor Grant calls ambiverts. Wait, what? Who’re they? These sales reps far outpaced both the intro and extroverts earning an average of $155 an hour. What makes an ambivert? On the seven-point personality scale, they ranked right in the middle at around four – being neither extremely introverted nor extroverted.

This is because ambiverts have the ability to both talk and listen, to assert and empathise, to be sociable and yet not overbearing. Which is good news, because it turns out that not many people are a one or a seven on the introvert/extrovert scale. Most of us fall somewhere in between.

While there is a popular perception that working culture favours extroverts with assertive, outspoken people having the advantage, Professor Grant suggests that extroverts actually be taught to model some of the quieter, more reserved tendencies of their less outgoing coworkers.

Introverts also need to work on their self-promotion to get ahead. This can be done through writing and sharing information online that positions you as an expert, taking public speaking courses or workshops to practice interacting with large groups, and having a well-honed elevator pitch prepared in advance for ad hoc networking opportunities.

It can be learned. I’m an introvert, I write and edit a website for a living. I used to be terribly shy. But I’ve had to work hard at becoming more extroverted to help promote Workopolis’ insights and career advice to greater audiences in the media and to large groups of people at conferences. The more you put yourself out there, the easier it gets.

So who wins: introverts or extroverts? I’m tempted to call this one a draw for now. What do you think?