It’s the time of year for that most festive of holiday traditions: lying to your children.

As a country, we expend a huge amount of energy convincing our kids of the existence of Santa. In one survey, 84 percent of parents said they had taken their child to visit more than two Santas that year. The U.S. Postal Service even helps parents provide replies to children’s letters to Santa complete with a North Pole postmark.

With all this work, it’s no wonder that 85 percent of 5-years-olds think Santa Claus is real, according to research by Jacqueline D. Wooley, a psychologist at the University of Michigan.

Psychologists argue about the effect of the Santa myth on kids, with some saying it is benign and others saying it is harmful.

In a recently published essay, Christopher Boyle, a psychologist at the University of Exeter, and Kathy McKay, a mental health researcher at Australia’s University of New England, write that the myth of Santa Claus affects children in ways that may not have been considered — and that it can undermine the trust of children in their parents.

Boyle and McKay say some white lies are appropriate. “An adult comforting a child and telling them that their recently deceased pet will go to a special place (animal heaven) is arguably nicer than telling graphic truths about its imminent re-entry into the carbon cycle,” they write.

But they do not put the Santa Claus myth into that category. Whether kids find out from a third party or a mistake made by parents, they will one day experience “the biggest moral breach of the Christmas lie,” Boyle and McKay say — and that may affect trust between parents and children.

“Children must all find out eventually that their parents have blatantly and consistently carried on a lie for a number of years,” they write. “If adults have been lying about Santa, even though it has usually been well intentioned, what else is a lie?”

Wooley, who recently wrote about her research at the Conversation and Quartz, takes a different view.

“There is no evidence that belief, and eventual disbelief in Santa, affects parental trust in any significant way. Furthermore, not only do children have the tools to ferret out the truth; but engaging with the Santa story may give them a chance to exercise these abilities,” said Wooley.

The existence of an elderly man with NSA-style surveillance of kids’ behavior and the ability to break into your house might seem far-fetched for adults. But children believe in Santa Claus because adults go to such great lengths to fabricate evidence for them — from encounters with mall Santas to personalized letters, says Wooley. “Given this effort, it essentially would be irrational for children not to believe.”

In addition, it’s not so clear to children where the magic of adults begins and ends, Alison Gopnik, a professor of psychology at the University of Berkeley pointed out in a recently aired episode of the podcast “This American Life.”

“Children understand that their parents for instance are powerful in all sorts of ways that make them very different from children. Now, from a child’s point of view, knowing where those powers begin and end is pretty tricky,” Gopnik says. “I mean, think about all the things that your parents can do that you can’t do. And think about the fact that there isn’t any obvious explanation about why your father can use a Visa card, for instance.”

In fact, Wooley’s research shows that children are rational, thoughtful consumers of information, who use many of the same tools of critical thinking as adults.

For example, her research shows that children use context to judge whether information is reliable. In one study, children were more likely to believe in the existence of a pretend animal called a “surnit” when they were told the animal was used by doctors and scientists, compared with when they were told it was collected by dragons and ghosts.

Her research also showed children are more likely to believe information when it came from a relevant expert. In another study, kids were more likely to believe in the existence of improbable animals, like a fish as big as a car, when they heard reports about it from a zookeeper rather than a chef.

Kids are likely to use these same analytical skills to one day detect the truth about Santa. And when they do, research suggests they may not be the ones who are disappointed.

A 1994 study that interviewed kids who had already discovered the truth about Santa found that they reported predominantly positive reactions about learning the truth. It was their parents who described themselves as sad.

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