But adults were a bit better at sniffing out the truth when a child lied about a false event, filling in the blanks to pretend that it took place.
Study co-author Gail Goodman, PhD, says in a news release that "the large number of children coming into contact with the legal system, mostly as a result of abuse cases, has motivated intense scientific effort to understand children's true and false reports."
Goodman is a psychology professor with the University of California, Davis.
She and her team had more than 100 adults view videotapes of 3- to 5-year-old boys and girls being interviewed about certain made-up or real events.
The children were asked things like: "Who was there when you got in trouble because you were playing on the rocks?"
Some of those events actually did take place; others were made up.
For the events that did happen, children either confirmed that it took place or denied that it occurred.
When it came to the made-up events, children either fibbed, saying that it did in fact happen, or they truthfully said that it did not take place.
The adult participants were then asked to watch the videotapes and to act as if they were a juror on a real case.
The researchers found that adults were "relatively" able to nail the made-up events.
But when it came to the denials, adults tended to believe when children lied that an event did not happen when it actually did occur.
Adults were "especially likely" to believe that a child was telling the truth when they made a denial.
"The findings suggest that adults are better at detecting false reports than they are at detecting false denials," Goodman says.
She says that "while accurately detecting false reports protects innocent people from false allegations, the failure to detect false denials could mean that adults fail to protect children who falsely deny actual victimization."