A baby's memory works from birth, and even before. A newborn recognises their mother's voice, a 3-month-old remembers a movement for several days, and an 18-month-old for several weeks. What little ones lack is not memory: it is the ability, later on, to retrieve those memories.
A baby's memory begins before birth
In the last trimester of pregnancy, the foetus hears the sounds that pass through the wall of the womb, starting with their mother's voice. In 1980, two American researchers, Anthony DeCasper and William Fifer, demonstrated this in the journal Science. Newborns just a few days old changed their sucking rhythm to hear their mother's voice rather than another woman's voice.
In other words, a baby comes into the world carrying traces of what they perceived in the womb. The smell and taste of amniotic fluid, which are also found in breast milk, play a similar role. These familiar cues soothe the newborn from the very first days.
What does a young baby really remember?
A baby doesn't remember the way an adult does, with dated stories. Above all, they memorise patterns: a voice, a face, a smell, a routine, the effect of a movement. Researchers distinguish several forms of memory, which develop at different paces.
- Recognition: your baby looks longer at a new image than at one they have already seen. This is proof that they have kept the first one in memory.
- Memory for actions: they repeat a movement that produced an effect, such as kicking their legs to make a mobile move.
- Deferred imitation: they later reproduce a gesture they have watched, without having practised it at the time.
The mobile experiment: how long does a memory last?
The American psychologist Carolyn Rovee-Collier devoted her career to a simple experiment. A ribbon is tied between the baby's ankle and a mobile hanging above their cot. The baby quickly discovers that kicking their leg makes the mobile move.
A few days later, the mobile is put back, this time without the ribbon. If the baby immediately starts kicking, it means they remember. The results, published in particular in 1998 in Developmental Psychobiology by her team, show a clear progression.
- At around 2 months, the memory lasts roughly one to two days.
- At around 3 months, it lasts roughly a week.
- At around 6 months, it lasts roughly two weeks.
- At around 18 months, with an age-appropriate task, it lasts several weeks, and more than three months in some trials.
Two other findings struck the researchers. First, memory is closely tied to context: simply changing the pattern on the cot bumper is enough to make it fail in the youngest babies. Second, a brief reminder, such as seeing the mobile move for a few seconds, reactivates a memory that seemed lost.
At what age does a baby remember what they see others do?
Deferred imitation appears during the first year. Studies carried out in the 1990s showed that 6-month-old babies reproduce, the next day, a gesture they saw just once on a puppet. At around 14 months, a child can reproduce a new action observed a week earlier, according to research by Andrew Meltzoff published in 1988.
It is this ability that makes toddlers such attentive observers. Our article on imitation and learning by observation explains how it shows up in everyday life.
What recent brain imaging shows
For a long time it was thought that the hippocampus, the brain structure that records memories of events, was not functional until several years of age. A Yale University study, published in Science in March 2025, strongly qualifies this idea.
Nick Turk-Browne's team used MRI to observe 26 babies aged 4 months to 2 years while they looked at images. When the hippocampus was more active in response to an image, the baby recognised it better afterwards. This encoding was more pronounced after 12 months, but already present in some younger babies.
Why do we have no memories of early childhood?
This phenomenon has a name: infantile amnesia. Most adults remember nothing from before the age of about three or four. And yet, as we have just seen, babies do form memories.
The hypothesis favoured by the Yale researchers is a problem of access rather than recording. Memories would be formed, then become impossible to find as the brain, language and sense of self are transformed. Ongoing research is trying to find out whether they persist in one form or another.
Forgetting an event doesn't mean it left nothing behind. The repeated experiences of early childhood shape expectations, habits and a sense of security, even without any conscious memory.
Memory and everyday landmarks: what really helps
Research on infant memory points to a simple idea: a baby remembers what is repeated in a stable setting. They don't need exercises or special objects. A few habits are enough.
- Routines: the same sequence at bedtime or bath time helps your child anticipate what comes next. Our article on routines and emotional security explains why this predictability is reassuring.
- The same play spaces: finding the same floor space every day, with a few familiar objects, gives them stable landmarks. A play mat always set up in the same spot plays this role.
- Repeating books and nursery rhymes: rereading the same picture book lets them recognise, then anticipate the pages. See at what age to start reading to your baby.
- Putting words to what is happening: naming a situation later helps your child organise their memories, once language arrives. Words for time come next, as described in our article on a child's sense of time.
Memory, name, face: milestones that echo each other
Several well-known stages of development rely on memory. Recognising their own name means having linked a sound to themselves; see our article on the age when babies respond to their name. Looking for a hidden toy means remembering that it exists: this is object permanence.
Recognising themselves in a mirror, at around 18 months, requires remembering their own face. Our article on the age when babies recognise themselves in the mirror explains how this milestone is observed.
Should you worry if your baby seems to forget?
No, in the vast majority of cases. A baby who doesn't immediately recognise a relative seen a month ago, or who seems to have forgotten a game, is behaving normally. Their memory still depends a great deal on context and reminders.
What is worth raising with the doctor is a loss of skills: a child who no longer does what they could do before, who stops babbling or responding to the people around them. In that case, it is best to see a doctor without waiting for the next routine check-up.
In summary
- A baby's memory works from birth: they recognise their mother's voice.
- A memory lasts one to two days at around 2 months, about two weeks at around 6 months, and several weeks at around 18 months.
- Context matters a great deal, and a brief reminder reactivates a forgotten memory.
- Infantile amnesia is thought to be mainly a problem of accessing memories, not of recording them.
- Routines, stable places and repetition are your baby's memory's best allies.
Sources
- DeCasper A. J., Fifer W. P., “Of human bonding: newborns prefer their mothers' voices”, Science, 1980.
- Hartshorn K., Rovee-Collier C. et al., “The ontogeny of long-term memory over the first year-and-a-half of life”, Developmental Psychobiology, 1998.
- Barr R., Dowden A., Hayne H., “Developmental changes in deferred imitation by 6- to 24-month-old infants”, Infant Behavior and Development, 1996.
- Meltzoff A. N., “Infant imitation after a 1-week delay”, Developmental Psychology, 1988.
- Yates T. S., Turk-Browne N. B. et al., “Hippocampal encoding of memories in human infants”, Science, 20 March 2025; Yale University press release of the same day.
