What comes out of the mouths of babes isn’t always the unvarnished truth.

Indeed, toddlers can start lying before they’re out of diapers, a new University of Toronto study shows.

“We were very surprised that so many kids lied and lied so early,” says Kang Lee, a senior child psychologist at the school’s Institute of Child Study.

Lee’s paper, published in the January edition of the American Psychological Association journal Developmental Psychology, pushes the onset of lying back some 18 months from the age previous research has suggested it would begin.

For the study, Lee enlisted 41 two-year-olds and 24 three year olds.

His team placed three toys behind the children’s backs and asked them to guess what they were by the sounds they made.

“Let’s say the first was a car and it made an engine sound and the child said ‘oh, it’s a car’,” he says.

The second might be a toy dog, which barked and was also easy to guess.

“Then we said there was a third toy and if you guess that right you get a prize,” Lee says.

“But the third toy, lets say it was a Barney, but we played music that had nothing to do with Barney so there was no way they could guess correctly what it was.”

The researchers would then leave the room, telling the children they could not turn to peek — which the majority of them were caught on hidden cameras doing within seconds.

And upon their return, Lee’s team asked the kids if they’d looked while they’d been left alone.

“What we found was about 25 per cent of the two year olds would lie to us,” Lees says.

What his team found as well was that those puny prevaricators were also more cognitively advanced than their truthful peers.

In particular, Lee says, the little liars had better developed “executive functioning” — the higher thinking skills that emerge as we learn.

They also had a more acute “theory of mind”, which allows humans to reasonably guess what other people are thinking.

“If, I were to lie to you, the reason I lie to you is because I know you do not know what I know,” he says.

“So that requires me to read your mind.”

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This does not mean, however, that early lying is a sign that the kids who do it are innately smarter than their truthful counterparts, Lee says.

“They’re not going turn into (geniuses),” he says.

Nor are they liable to become chronic liars as they mature, Lee says.

Indeed, by the time children reach the age of seven, almost 100 per cent of them will lie to cover mistakes or transgressions.

Lee’s past research has helped to push the onset of lying back from school aged children to three year olds.

“Going back 30 years ago people thought that kids simply do not lie until they get to elementary school years or even later,” Lee says.

“But in the last 10 to 15 years we have been looking at kids from three and above and we found half of three year olds would tell lies.”

Lee’s latest study may even indicate that children start equivocating at pre-verbal ages.

“So far I don’t have a scientific method (to test this) yet,” he says.

“But I suspect I can still find some (non-verbal) kids were capable of telling lies with actions or with other means of communications.”

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