That’s true of music, clothes and cars, but not so true of dishwasher soap. Tech gadgets fall in between those extremes, he says. A new gadget can be a fashion item — a revelation that Apple embraced long ago.

Image Buying on Day 1: Sayuri Watanabe came from Japan to be among the first to get an iPad last month at the Apple store in downtown San Francisco. Credit... Jim Wilson/The New York Times

Dan Ariely, a professor of behavioral economics at Duke University and the author of a new book, “The Upside of Irrationality,” has studied why earlier adopters do what they do. “It’s not about the cost-benefit analysis,” he says. And rarely is it a successful calculation of higher productivity, though many a person has tried to justify purchases of expensive toys that way.

It can be more about cementing one’s identity. Although people who want to be first with a product aren’t making a direct calculation — “I’d pay $100 for my ego” — they may derive value from showing off a new product or being perceived as being at technology’s forefront.

“I realized years ago that I derive great pleasure from buying a new gadget,” said Professor Ariely. “I bought a Segway.”

And public awareness may matter. Professor Ariely says the behavior is akin to how we can be more willing to do something good if the public knows about it. People will pay extra for a Prius, whose ecological benefits may be debatable, but be more circumspect about buying extra home insulation, which is one of the best ways to save energy.

Your friends will see you cruising in the Prius. (Indeed, no car has driven so far on sanctimony.) No one will ever see the extra two inches of R-38 in your attic.

But even if you would never be the first in your neighborhood to buy a gadget, don’t scorn the early adopters. They are working for you. “They, in a sense, provide valuable services to other consumers by their willingness to serve as a guinea pig,” said Jay Pil Choi, a professor of economics at Michigan State University, who wrote a much-quoted paper on herd behavior and the “penguin effect.”