A baby suddenly stops crying the moment you pick them up. A toddler hides something after being told not to touch it. A little one shakes their head and insists they did not eat the chocolate, even though the evidence is all over their face.To a parent, these moments can look surprisingly like lying.
28 Jul 2026 | 16:26
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But babies are not born with a fully developed understanding of truth, consequences or other people’s beliefs. So when researchers talk about “deception” in very young children, they are referring to something much broader: behaviours that appear to involve hiding information, avoiding an unwanted outcome or influencing what another person does.And new research suggests these behaviours may appear much earlier than many parents would expect.
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Babies may show signs of deception earlier than expected
A 2026 study published in Cognitive Development developed the Early Deception Survey to examine deceptive behaviours in children aged 10 to 47 months. The researchers collected reports from parents across several studies and identified 16 different types of deceptive behaviour.Interestingly, the earliest reported example came from a child just 8 months old. In the researchers’ sample, they estimated that 25% of children had engaged in at least one type of deception by around 10 months, 50% by 16 months and 75% by 24 months.But there is an important catch: these findings do not mean that babies are sitting down and deliberately inventing elaborate lies.The study relied heavily on parents’ observations and interpretations of their children’s behaviour. The researchers themselves point out that deception in babies is difficult to measure because it is hard to separate an intentional act from ordinary infant behaviour. In one part of the research, parent reports did not correspond closely with laboratory measures of deception.So, “my baby lied to me” is probably not the most accurate way to understand what is happening.
What does deception look like in a baby?
For a very young child, deception can be surprisingly simple. It might involve hiding an object, pretending not to hear a parent, denying having done something, distracting an adult or carrying out a forbidden activity when the adult is not looking. As children become older and their language and thinking abilities develop, the behaviours can become more complicated- such as making excuses, exaggerating, withholding information or fabricating a story.The progression matters. A baby who learns that crying brings an adult closer is not necessarily “manipulating” the parent. The baby is learning a basic connection between their behaviour and another person’s response.A toddler who hides a toy after being told not to touch it is demonstrating a slightly more advanced understanding: If Mum sees this, something may happen, so perhaps I should hide it.That growing ability to think about what another person knows, sees or believes becomes increasingly important as children get older.
Lying requires more brain power than it looks
Research on children’s lying has consistently linked it with two important cognitive abilities: theory of mind and executive function.Theory of mind is the ability to understand that another person can have thoughts, knowledge or beliefs that are different from your own. Executive function includes skills such as holding information in mind, controlling impulses and switching between ideas.A 2021 meta-analysis combining 47 studies and more than 5,000 participants found small but significant associations between children’s lying and both theory of mind and executive function.Another meta-analysis, which included 81 studies involving 7,826 children aged 2 to 14, also found a significant relationship between theory of mind and lying. The connection was particularly noticeable when children had to maintain a lie rather than simply produce one.This helps explain why sophisticated lying develops gradually. A child has to remember what actually happened, work out what another person knows, decide what to say instead and keep the story consistent.That is a lot of mental juggling for a small brain.
So, should parents worry?
Seeing a toddler hide something or deny an obvious misdemeanour does not mean the child is dishonest, manipulative or headed for behavioural problems. Deception is part of normal cognitive and social development, and researchers have found that it becomes increasingly sophisticated as children develop language, memory and social understanding. The more useful response is to look at why the child is doing it.Are they afraid of getting into trouble? Trying to avoid disappointment? Testing whether a rule really applies? Experimenting with what another person can see or know?That question is often more useful than simply labelling the child a “liar”.
How parents can respond
For babies and very young toddlers, there is little value in confronting them about honesty. They are still developing the cognitive skills needed to understand deception in the way an older child does.As children become more verbal, parents can calmly state what they know rather than turning the moment into an interrogation.Instead of repeatedly asking, “Did you do it?” When the answer is obvious, try: “I can see what happened. Let’s talk about it.”That leaves room for the child to tell the truth without feeling trapped. It is also worth remembering that children learn about honesty from everyday interactions. They watch how adults handle mistakes, promises, uncomfortable questions and even small social lies.The bigger lesson from the new research is therefore not that babies have suddenly become tiny con artists. It is that the social brain may be getting to work much earlier than we once realised. What looks like a cheeky little trick today may actually be part of a child’s gradual discovery of a complicated idea: other people have minds too- and what they know, see and believe can be different from what I know, see and believe.
