They secretly snack on chocolate, deliberately ignore parents’ instructions or hide toys from others: over the course of their first years of life, children develop various strategies to gain advantages. Science has long assumed that the ability to understand and use deception requires an advanced understanding of the minds of others. But now a study based on parent surveys shows that some babies try to deceive others as early as around ten months old and can see through when they themselves are being deceived.
Around the age of three, children develop the ability to empathize with others. They understand that other people do not have the same knowledge or the same thoughts and feelings as they do. For a long time, this so-called theory of mind was considered a prerequisite for using conscious deception. Small children, it was believed, did not yet have the cognitive basis for lying and deception.
Easier than expected
A team led by Elena Hoicka from the University of Bristol in Great Britain now contradicts this view. “Previous research has often viewed deception as something very complex, requiring strong language skills and an advanced understanding of other people’s minds,” says Hoicka. But studies on animals such as chimpanzees, capuchin monkeys, antelopes and birds show that they also deceive their fellow animals by, for example, hiding food from them. “This suggests that deception requires neither language nor a strong theory of mind,” the researchers conclude.
Inspired by animal fraudsters, Hoicka and her colleagues developed a questionnaire that contains 16 different rudimentary forms of deception and can be used for babies and toddlers. “As a mother of three children, I can attest to how sophisticated and smart they can be,” says Hoicka. “One of their common tricks is to hide under the table or in the bathroom to eat candy.” Other recorded behaviors include intentionally ignoring unpleasant instructions, hiding objects from others, or denying one’s own guilt.
Little fraudsters
In several rounds of surveys, the research team had the parents of more than 750 under four-year-olds fill out the questionnaire. The respondents stated at what age their offspring began to show the corresponding behavior and at what age the child was able to see through if they were being deceived in this way. The result: Around a quarter of the children began to understand and use deception at the age of ten months. One of the earliest behaviors is to hide a toy to avoid sharing it with others. At around eleven months, some children began to do forbidden things in secret and at twelve months the first ones shook their heads untruthfully when asked, for example, whether they had eaten chocolate.
“It was fascinating to uncover how children’s understanding and use of deception develops at a surprisingly young age and is consolidated in their first years of life, so that they become quite adept ‘little liars,’” says Hoicka. From around the age of three, children expand their repertoire of deception, use exaggerations or understatements to their advantage or invent lies. “They also begin to withhold information, for example by telling their parents that their sibling hit them, but omitting the fact that they hit their sibling first,” Hoicka reports. “Three-year-olds also begin to use distraction tactics, such as telling someone, ‘Look over there!’ when they want to do something they’re not allowed to do.”
Useful ability
Children’s deceptive abilities developed particularly quickly when parents themselves regularly tricked their children or encouraged them to commit small deceptions on others. Even though most parents surveyed do not consider deception to be desirable, the research team explains that this skill is an important part of children’s development. “It is a common form of communication that children have to learn to use in order not to be misled by others,” say the researchers. “It is also a strategy that allows a less assertive child to balance a power imbalance, and is therefore a key skill that children need to assert their interests in interactions with adults or other children.”
From Hoicka and her colleagues’ perspective, the study can help parents and educators to better categorize dizziness in children. “Parents can be reassured that deception is completely normal in the development of young children,” says Hoicka. “You can also look at our results to learn what types of deception to expect based on age, so you can better understand and communicate with your children to stay one step ahead of their deception attempts.”
Source: Elena Hoicka (University of Bristol, UK) et al., Cognitive Development, doi: 10.1016/j.cogdev.2026.101677