...in one interesting study, a group of researchers led by Roy Baumeister at Florida State University found that if you made people feel socially isolated..., it would decrease their sensitivity to the plight of those around them. To demonstrate this, they created a clever (though somewhat harsh) experiment. They had participants complete a bogus personality questionnaire and then told some of them that, based on the results, they were the type of person who most likely would not be able to develop meaningful relationships later in life and thus would end up alone....
Turned out that the people led to believe that they would become socially isolated did indeed care less about [others]. Not only that, it also made them less likely to engage in any prosocial behavior in general, and even made them less sensitive to emotional and physical pain. In short, it numbed them. It seems that when the possibility of developing beneficial long-term relationships is removed, either because the person in need doesn't appear to be the type of person who is worth your efforts (i.e., is dissimilar to you) or because you have reason to believe that you are unlovable and so your efforts would be fruitless, ... your impulse to care about the suffering of others switches off. If you can't count on anyone besides yourself, you might as well live only for yourself, right? [Desteno & Valdesolo, Out of Character, 147-148]
This research suggests that socially isolated individuals would be more receptive to the idea of living only for oneself. This could mean one of two things when related to Objectivism: (1) it could mean that Objectivism would appeal to social isolated individuals; and (2) that Objectivism has a built-in incentive to make people social isolated, since this will increase the chances that this individuals will accept and remain true to the Randian creed.
Let's first examine the appeal that Objectivism might have to the socially isolated. One issue that Objectivists tend to be naive about is the degree to which ideologies are, in a sense, self-selecting. That is to say, people tend to choose ideologies, not because of the acceptance of some premise or the logic of some argument, but because that ideology appeals to their needs, desires, and/or weaknesses. Generally speaking (there may be exceptions), people don't become Objectivists because they are convinced by Rand's premises or arguments; rather, there is something they find emotionally appealing in Objectivism, which leads them later to adopt a speculative allegiance to Rand's premises. Rand's philosophy strikes them as true and enlightening, despite the absence of sound argument and compelling evidence.