Little liars: babies younger than one practise deceit, study suggests | Children

They may not have taken their first step or spoken their first word yet, but research shows that some babies have grasped the basics of infidelity before their first birthday.

The research, based on interviews with 750 parents, suggested that by 10 months, around a quarter of children had practiced some basic form of deception, such as pretending not to hear their parents, hiding toys or eating forbidden foods out of sight. According to parents’ responses, by age three, children were more resourceful, creative, and crafted more often.

“It was fascinating to uncover how children’s understanding and use of deception develops from a surprisingly young age and evolves throughout their early years,” said Elena Hoicka, professor of education at the University of Bristol and lead author of the study.

So far, little research has been done on the earliest forms of deceptive behavior, Hoicka said. “Previous research has generally focused on deception as a very complex thing that requires strong language skills and an advanced understanding of the minds of others,” Hoicka said.

The latest research drew on animal behavior studies that document apparent deception without the need for verbal communication. For example, chimpanzees often hide to eat out of sight of more dominant group members, while birds have been documented making false alarm calls to steal food.

“It’s not like the ability to deceive suddenly appears three or four years later,” Hoicka said. “Previous forms aren’t necessarily all-out cheating. It’s probably more about getting away from things or getting extra treats.”

“As a mother of three myself, I can definitely vouch for how ingenious and cunning they can be,” she added. “Hiding under the table or in the bathroom to eat sweets or chocolate is their common trick.”

Researchers asked parents of more than 750 children aged 0 to 47 months in the UK, US, Australia and Canada a series of questions about their children’s development of infidelity.

Some participants reported that their children were first introduced to this concept at eight months of age. It was also observed that deception activities were frequent. The study showed that half of the children who said their child was cheating once they started did something sneaky on the last day.

From the age of two, deception tends to be action-based or requires only basic verbal responses, such as pretending not to hear their parents say “time to clean up”, hiding things from others, or denial, such as shaking their head to say “no” when asked if they have eaten chocolate.

The findings showed that children begin to understand and engage in more types of deception by the age of three; this often involves a deeper understanding of language and how other people’s minds work.

“This can mean exaggeration, understatement, or complete fabrication, such as telling a lie like ‘the ghost ate the chocolate,’” Hoicka said. “They also begin to withhold information, such as truthfully telling their parents that their sibling hit them, ignoring the fact that they hit their sibling first.”

He said the research should reassure parents and educators that deception is normal in toddler development and provide a guide to what types of deception can be expected, so they can “stay one step ahead of their deception.”

Professor of the philosophy of deception and co-author of the study from the University of Waterloo in Canada. Jennifer Saul said: “Philosophers have long considered the morality of human infidelity, but they have always focused on adults cheating on each other. This study shows how much complexity that focus misses.”

The findings were published in the journal Cognitive Development.