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Liar, liar, pants on fire? Your baby will be the judge

James Cheng /

Babies may be a lot more savvy than we think.

A new study has found that babies little more than a year old can tell whether we’re trustworthy enough to listen to, according to a report published in Infant Behavior and Development.

“Even at a young age, children do not blindly swallow information,” said the study’s lead author Diane Poulin-Dubois, a professor of psychology at the Centre for Research in Human Development at the University of Concordia. “Doubtful or contradictory information is automatically screened by their cognitive system. Young children are not gullible.”

To determine whether babies took everything at face-value or whether they actually mull over the credibility of the people around them, Poulin-Dubois and her colleagues set up an intriguing experiment involving 60 babies aged 13 to 16 months.

Half the babies would interact with a “reliable” adult, while the other half would interact with an “unreliable” one, while playing with a box that in some cases contained a toy and in others was empty.

In the first part of the experiment, the adult would look inside the box and express excitement and happiness. Then the babies were invited to look inside the box themselves to see what the fuss was about.

Unreliable adults were the ones who ooo’d and ah’d over empty boxes, while reliable ones made a fuss only when there was a toy inside.

The second part of the experiment used the same adult-baby pairs. This time the adult used her forehead instead of her hands to turn on a push-on light. The idea was that babies who trusted their new adult friends would try to imitate them.

Sure enough, babies were much more likely to try using their heads to turn on the light if they’d played the “what’s in the box?” game with a “reliable” adult, compared to those who’d played with an “unreliable” one.

For little ones, what it all comes down to is survival.

“We are a very social species and human offspring are dependent on their caregivers for a long time,” Poulin-Dubois explained. “Learning from others is key to cultural learning but it comes with potential costs, such as inaccurate information. Being equipped with an ability to detect ‘unconventional’ or unreliable people is a protection against acquiring false information.”

One of the simplest examples of this is the credibility conferred on adults, Poulin-Dubois said.

“Age is one of these cues and is used by infants and preschoolers,” she added. “They will imitate an adult more than a child unless the adult seems unreliable and the child reliable.”