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Turns out "Don't squeeze the Charmin" might have been the worst marketing message of all time. According to a new study to be published in an upcoming issue of the Journal of Consumer Research, consumers who touch products in the aisles will pay more money for them than those who keep their hands off the merchandise. So in the 21 years Procter & Gamble ran the iconic television advertisements for its Charmin toilet-paper brand, Mr. Whipple, the uptight grocer with a secret squeezing fetish, should have encouraged his bubbly shoppers to fondle away.

Why does touching an item increase the likelihood of purchase? The motivation traces back to what behavioral economists have labeled the "endowment effect." This phenomenon posits that consumers value a product more once they own it. And simply touching that Charmin may increase a shopper's sense of ownership and compel the consumer to buy the product. (Read "How to Know When the Economy Is Turning Up.")

"When you touch something, you instantly feel more of a connection to it," says Suzanne Shu, a marketing professor at UCLA's Anderson School of Management and co-author of the study. "That connection stirs up an emotional reaction  'Yeah, I like the feel of it. This can be mine.' And that emotion can cause you to buy something you never would have bought if you hadn't touched it."

To prove the power of touch, the researchers placed two products, a Slinky and a coffee mug, in front of 231 undergraduate students at the University of Wisconsin. About half were told they could touch the products, while the other half were prohibited from fiddling with them. Students were then asked to express their sense of ownership of the products and to indicate how much money they were willing to pay for each.

The results were clear: those who touched the items reported statistically significant higher levels of perceived ownership. They were also willing to pay more to purchase the products. "If you don't want to spend more money, be careful what you touch," says Joann Peck, a marketing professor at the University of Wisconsin's business school and the study's other co-author. Peck happily describes herself as an expert in haptics, the science of touch; she has published six other papers on the subject. "Touching something gives you that little sense of control," she says, "and that alone can increase your feeling of ownership."

While cash-strapped shoppers might want to start tying their hands behind their backs, retailers should hang signs that say "Feel me." For a subtler approach, the authors single out the Apple Store as a model. Apple openly invites its customers to fidget with its gadgets, and once you start playing with the iPhone, it's awfully hard to leave the place without one. Shu says that at Office Depot, she has seen pencil packages with holes in the plastic. These holes encourage consumers to poke around. (See the best business deals of 2008.)

So some stores already have the right touch. But can online merchants benefit from our haptical habits, given that you can't feel a product on the Web? The answer is yes, as long as the sites compel consumers to do the closest thing possible to touching something: imagine that they're touching something.

To test this hypothesis, the authors added an extra layer to the experiment. After the students either touched or didn't touch the Slinky and the coffee mug, they were asked to imagine picking up the products and bringing them home. The other half were asked to simply evaluate the products in their minds. Among those who touched the products, imagining ownership did not affect the price they'd be willing to pay for them. However, among those who didn't touch the items  a group that shares the same hands-free experience as online shoppers  picturing ownership led to significantly higher valuations of the products.

This result offers an important lesson for online retailers. Even haptical illusions can have powerful effects on purchasing decisions. If a site displays a set of towels and asks shoppers to picture holding those bright, fluffy towels in their hands, it could improve its shot at notching a sale.

And if you're a consumer looking to save, clear your head. You can't even think about touching.

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