4 mo
Out of sight, out of mind
6 mo
child will look at a book
8 mo
out of sight, but may still exist and have fallen to ground
1 yr
object permanence. Looks for hidden object.
18 mo
search for object after seeing it moved. Brings book for parent to read.
2 yrs
knows objects exist if gone. Wants same story over and over.
4 yrs
symbolic thought. concrete thinking. egocentric.