Changing people's minds isn't as hard as you think.

It's harder.

That's because a person's viewpoint can be so ingrained into their self-concept, they won't allow themselves to think any other way.

Take a self-proclaimed environmentalist. By default, he is going to be against oil drilling in the Arctic National Wildlife Refuge. You could present dozens of facts demonstrating that drilling there is a workable and sound idea. And he might have few or no facts against drilling. But it won't make a lick of difference. The way he sees it, to maintain his identity as an environmentalist, he must be against it.

Lisa E. Bolton and Americus Reed, two researchers at the University of Pennsylvania's Wharton School of Business, met with people who strongly identified themselves as Republicans, teenagers, parents, businesspeople, and so on. The professors found that it was virtually impossible to sway the subjects from their standard position on key issues. It didn't matter what rhetorical tactics the professors used. The participants tended to dismiss anything that was counter to their position as propaganda from the dark side.

The professors believe this is why smokers – many of whom consider 'smoker' to be part of their identity – often disregard anti-smoking ad campaigns that focus on negative health effects. More effective, say Bolton and Reed, are messages that help people develop a self-concept that is inherently anti-smoking, such as "athlete" or "savvy teen" who won't be sucked in by the big tobacco companies.

For those of us trying to build brand loyalty, the implications are huge: If you can make your product or service not just something people use, but rather part of who they are – think Harley Davidson – you become immune to attack from the competition. Someone else can offer a product that's cheaper or maybe even better. But the customer who has made you part of his identity won't even hear what the rest of the market is saying.

Read a summary of findings at the Knowledge@Wharton web site (requires free registration), or see a full report of the findings in the November 2004 issue of the Journal of Marketing Research (subscribers only; non-subscribers can download the article for $24.)