Finding a hidden toy
Most babies start looking for a toy they have just seen you hide at around 6 to 8 months. In a small study that followed babies closely, all of them started between about 6½ and 8½ months.
How sure are we?
Fairly sure. A large study in four countries and a small study that tested babies closely agree, but the large study asked parents a broader question, and there are only two studies so far. How we know this
What it’s a sign of
Your baby is starting to keep things in mind when they can no longer see them, and to act on that memory.
Studies that measure where babies look suggest they may expect a hidden toy to still be there months before they search for it. Some researchers think early searching mistakes, like looking in the old hiding place, come from habits of reaching rather than from forgetting. The CDC lists looking for something you hide at 12 months, later than these ages, because it uses the age by which about 3 in 4 children do it, rounded up to a check-up.
Large studies that watch babies search are missing, so we don't know how late the healthy range runs. Most of the research is from a few countries.
A classic study on this
Development of the Ability to Use Recall to Guide Action, as Indicated by Infants' Performance on AB
Adele D. Diamond · 1985 · Child Development
- Children
- About 25 babies
- Where
- Boston, United States
- Ages
- 6 to 12 months
- How
- Researchers tested the same babies every 2 weeks as they grew
- What it found
- Babies first uncovered a toy they had watched being hidden at about 7½ months on average, all between 6½ and 8½ months. Girls tended to start a little earlier than boys.
- Limits
- A small group of mostly well-off families in one city. Read from a scanned copy, so the figures need checking against a clean copy.
A main source for the ages
Similarities and differences in child development from birth to age 3 years by sex and across four countries: a cross-sectional, observational study
Ilgi Ozturk Ertem, Vibha Krishnamurthy, Mphelekedzeni C. Mulaudzi, Yanina Sguassero, Hakan Balta, Ozlem Gulumser · 2018 · Lancet Global Health
- Children
- About 4,900 healthy children
- Where
- Argentina, India, South Africa and Turkey
- Ages
- Birth to 3½ years
- How
- Trained staff asked parents open questions about what their child could do, at health clinics
- What it found
- Found the age by which half of children reached more than 100 milestones. Most came at similar ages in all four countries, and for boys and girls. For example, half of children waved bye-bye by about 11 months and said a first word by about 9 months.
- Limits
- Only four countries and no rural areas, children from city clinics, and only healthy children (about half of those who came were left out for health reasons). It gives the age for half of children, not the full spread.
A main source for the ages
Evidence-Informed Milestones for Developmental Surveillance Tools
Jennifer M. Zubler, Lisa D. Wiggins, Michelle M. Macias, Toni M. Whitaker, Judith S. Shaw, Jane K. Squires, Julie A. Pajek, Rebecca B. Wolf, Karnesha S. Slaughter, Amber S. Broughton, Krysta L. Gerndt, Bethany J. Mlodoch, Paul H. Lipkin · 2022 · Pediatrics
- Children
- A review of 34 studies and common checklists, not one group of children
- Where
- Studies from many countries (14 of the 24 with age data were from countries where English isn't the main language)
- Ages
- 2 months to 5 years
- How
- Experts reviewed studies and checklists, then placed each milestone at the check-up age by which about 3 in 4 children do it
- What it found
- Places calling a parent "mama" or "dada" at 12 months, and saying 1 or 2 other words at 15 months. These are ages by which about 3 in 4 children have started, rounded up to a check-up age.
- Limits
- Experts' judgement set the ages, and some milestones rest on opinion rather than measured ages. The lists haven't been tested to see whether they help.
A study that questioned earlier findings
Knowing in the context of acting: The task dynamics of the A-not-B error.
Linda B. Smith, Esther Thelen, Robert C. Titzer, Dewey McLin · 1999 · Psychological Review
- Children
- Not given in the summary we read
- Where
- Not given in the summary we read
- Ages
- Babies in their first year
- How
- Lab experiments on reaching
- What it found
- Argues that when babies search in the wrong place, it comes from how reaching habits build up, not from forgetting where the toy is.
- Limits
- We have only read the summary.
If you’re worried about your child, talk to your child and family health nurse or GP.
Last checked 2 November 2026