Rozin puts this into dining-out terms. "You're going to a restaurant that you know is great—you've been there before, and you even know what you're going to order ahead of time. So you have anticipatory pleasure—you're looking forward to it, you experience it in advance, and then the actual experience is great; it's just as wonderful as you remembered. But your remembered pleasure of it later will be almost zero, because you've had it several times before, and all those memories merge together."

He proposes an alternative approach, which is his personal preference. What if you go to the same restaurant but order something you've never had before? "Your anticipation will be clouded—you don't have this image of what you're going to enjoy. The new dish may be great, or it may not be as good as what you usually get. But trying something new has given you another experience, so when you look back on that restaurant, you'll have more to think about. The memories will be more powerful."

All of this, Rozin explains, is about maximizing pleasure—and that's where he sees a major difference between Americans and Europeans. Consider vacations. You can take a nice, easy Caribbean vacation, have great anticipatory and present-tense pleasure, and very bland memories—everything blends together into one sunny day. Or you can go to Italy, in which your anticipation mingles with some anxiety ("will the car work? will we get lost?") and the actual experience from moment to moment might sometimes be challenging. But it would create new and specific vignettes: "We went to Siena and saw this great cathedral, and we had this amazing meal..."

"When you indulge in the same, albeit pleasant, experience over and over," Rozin says, "you're not building memories of the richness of your life. You're doing other things, and maybe you're having a hell of a time. But cultures differ with this, and Americans in general like to make their lives easy. Europeans prefer to make life interesting." Rozin is a "memory person"—the one who orders something new, or who would rather have adventures in Europe than lie on a beach.

This search for new experience—what some might call small-scale risk-taking behavior—has sometimes driven Rozin to almost lawless lengths. There was the time he was visiting Spain and wanted to go to El Bulli, a restaurant on the Costa Brava famous for its astonishingly long meals—some 30 courses, which are served over five-plus hours. It's open only six months a year and is usually booked a full year in advance, and Rozin was unable to secure a reservation before traveling there. Such was his desperation for the gastronomic adventure that he squeezed under the restaurant's gate and begged shamelessly, and futilely, to be allowed to dine there. (He says with a mixture of pride and envy that his youngest son, Lex, a music theorist academic and serious cook, is the only person he knows who has feasted at El Bulli twice.)

But Rozin isn't a food snob: His dedication to pleasure makes him just as happy scarfing down a five-dollar lunch as he is relishing a five-hour haute cuisine dinner. After our spanakopita, we wander over to the L.D. Bassett ice cream stand, and Rozin tutors me on the proper techniques for savoring every molecule of flavor: "Hold it on your tongue and let it start melting there. Then feel its smoothness as it turns into goo," he says, doing exactly that with his scoops of butterscotch vanilla and mango-apricot sorbet. "Most Americans don't eat slowly, enjoying each bite; we tend to gulp it down."