the psychology of spending; Why, Jane Herman asks, do we splurge on one thing, skimp on another, and then break the bank just because we're on vacation.

Byline: Jane Herman

On an afternoon shopping excursion in uptown Manhattan, a young woman and her very stylish mother-in-law decide to stop into Carolina Herrera. A stiff-collared coatdress in the window has caught their attention. It has everything the mother-in-law wants for fall: a moody, rich color, exaggerated proportions, and the careful mix of maturity and fashion-forwardness. So

she tries it on, and in minutes she's sure. She'll take it. That the price tag is nearing five digits is of no concern. Then the salesman suggests that the mother-in-law might also like the belt to match. She asks him what it costs. Not even $100, nothing compared with the high price of

the coatdress. It should be an easy sale. Instead, a tedious hour-long debate about the

overall value of the belt ensues: Does the coatdress look better with or without the belt? Does the fact that they match make the whole thing look cheap? Would the belt even be an issue if it were more expensive, the younger woman wonders? "A hundred dollars seems like a lot for such a simple belt," her mother-in-law says. Maybe she could substitute something else, a belt she already owns: "My Hermes would work, right? Do I really need this one?"

I mean, does she really need it?

Why a woman succumbs to the cost of some garments and not others is hard to puzzle out. One would think that we spend our money because we believe that the dollar amount we're being asked to forfeit accurately reflects what we're getting in return. But the psychology of spending-the way we rationalize price, calculating how an item addresses not just our taste but our emotional needs and neuroses-means there's much more to shopping than pure, hard economics. We purchase things even when we know we shouldn't. We spend small fortunes on shoes but buy our dresses only after they've gone on sale. Or vice versa. We'll spend thousands on pants that don't quite fit because they're a sample-sale "bargain." And just because we can afford Dress A and can't afford Dress B doesn't mean Dress A is the one we'll buy.