From the age of about 12 months , children show an interest as adults demonstrate symbolic play ; brushing a doll’s hair ,giving the doll a meal , pushing a toy man in a toy car , and begin to join in with these games , more or less competently . At 15 months , Rebecca watches intently as an adult dresses and undresses a doll , then tries this herself / She will , however , need to be somewhat older before she can get the arms and legs into the right holes . She likes to join in putting the doll to bed and waking it up , and then makes her own version of the game by discarding the doll and substituting her favorite monkey . All the games involve a considerable amount of repetition