The study found that those of us who play WoW for socialization are higher on the scales of agreeableness, neuroticism, and openness. Neurotic in this sense might not mean what you think it means; it's part of the Big Five personality dimensions that are commonly used in psychology. People that are high on the scale of neuroticism are, in general, less emotionally stable, have higher anxiety, and can get angry quicker (this shouldn't surprise anyone that reads the forums and the tweets Blizzard staff get). Neuroticism doesn't mean that you're insane, just that you have some of the personality traits described above. Quite literally we are all somewhat neurotic in this sense, it just matters how far along the scale you are (those on the extreme high-end of the scale are where the traditional/societal definition comes from).
Those that seek leadership in WoW tend to be high on the extraverted (meaning they prefer groups and interactions with others), openness, and conscientious scales. Those in leadership (as one could reasonably expect) tend to be highly organized, like to plan things out, and are lower on the neuroticism scale.
What I find particularly interesting is that this study lends strong support to rejecting the notion of the WoW player as an introverted kid playing in Mom's basement. It's been my experience that most of the players, especially on WoW Insider, continue to play because of the strong social connections made in the game. Whether the guild and/or your WoW friends are a primary factor in the "fun" the rest of the game delivers, or if you just like hanging out with them virtually for no other reason than to enjoy their company, the strong social is an integral part of the game these days. This study found that for those types of players, well, they've got the same personality traits as you'd expect from other strongly social people; not at all the South Park retelling.
An important note however, is one that Dr. Elisabeth Whyte (WoW Insider's Chief Correspondent of Academia and Smart Stuff) pointed out to me on Twitter this morning -- this study also found that personality actually factors only a little in why people do these things in WoW. There's a lot of outside factors -- for instance my need play WoW for socialization might not be based at all on my personality. It might just be based on how awesome the default font in the chat window is, or how much I like killing internet dragons.
The research was carried out by Lindsay Graham, a graduate student at the University of Texas at Austin, and Dr. Samuel Gosling, a professor of psychology at the school. The research results were published in the March 2013 issue of Cyberpsychology, Behavior, and Social Networking.