No matter what 7-year-old Adyn and 4-year-old Ayla Chidester are doing, they know Jimmy the Elf is watching.
The kids say it's Jimmy's job to tell Santa whether they've been naughty or nice. When Adyn's about to misbehave, he stops himself because he sees Jimmy staring right at him.
"I didn't want to help my sister, but Jimmy was watching so I helped her clean up her toys," he said.
But Dr. Stephanie Marcy at Children's Hospital Los Angeles says this may result in lazy parenting.
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"My concern as a pediatric psychologist is that parents are using the elf and even Santa Claus as a way to get their children to behave," Marcy said.
Marcy says using these elves to instill fear and manipulate a child's behavior could be seen as an intrusive mode of surveillance.
"It ends up making them in some ways a little suspicious, and in the long term, it can create even maybe a little paranoid affect," she said.
Is there a difference between the Elf and the Shelf and Santa Claus? Marcy says there is a fundamental difference.
Santa Claus is an abstract idea, whereas the Elf on the Shelf is right there in your house.
That "tattle tale" elf can backfire and even breed resentment, experts say. But Marcy says don't banish the elf from your house. Just keep the tradition light-hearted and humorous.