In the emotional minefield of gift-giving, the gift card may be the closest thing to full-body armor.

Gifts are an enduring ritual that predate plastic toys, the boob tube, newspaper circulars, and holiday "doorbuster" sales.

A lot more is on the line than just getting a warm smile.

"It's part of the courtship rituals of even nonhuman animals, and it's a way of maintaining peaceful relationships," said Carole Burgoyne, a psychology researcher at the University of Exeter in England. Her expertise is the study of gift-giving, with an emphasis on cash.

In a study Burgoyne conducted with university students, the social pressure to pick the perfect present was plain to see.

"We asked some people what would happen if you didn't give your girlfriend a present this Christmas," she said, "and the guy said, 'Well, I'd be single.'

"It's as simple as that. Getting a gift wrong . . . does have consequences, it does affect the relationship, so a lot is at stake."

In other words, a gift is a referendum on a relationship. And no one wants to lose.

Experts say gift cards are sweeping the United States and parts of Europe in part because they are a panacea to the performance anxiety of buying gifts. They are a "safer choice," Burgoyne said.

In lay terms, gift cards reduce the odds of giving a dud.

In economic terms, cash is the most efficient gift. People derive the greatest value from things they've chosen for themselves, said professor Joel Waldfogel of the Wharton School of the University of Pennsylvania.

"It's sort of a can't-miss gift from the standpoint of producing satisfaction," he said, "but it doesn't produce some of the special stuff."

Gift cards, Waldfogel said, are less efficient but help people avoid blunders - which are common among aunts, uncles and grandparents, who are more out of touch with their nieces and grandchildren.

"Their gifts," he said flatly, "are the least appreciated per dollar spent."

Contact staff writer Maria Panaritis at 215-854-2431 or mpanaritis@phillynews.com.