when a child understands that things and events continue to exist even though one can't see or hear them, we say that the child understands
http://books.google.com/books?id=2jCCXcJWZmAC&pg=PT148&lpg=PT148&dq=child+understands+that+things+and+events+continue+to+exist+even+though+one+can't+see&source=bl&ots=46nWWk3Gj2&sig=wrwbL_Mtk7Gn115gy32ARFYvdIw&hl=en&ei=nUPeSoCdMZC9lAeZmKk8&sa=X&oi=book_result&ct=result&resnum=5&ved=0CBAQ6AEwBA
extremely autonomous children
That's not the term that I read in that web site.
Autonomous children are independent; it has nothing to do with their perception of items and people who aren't in sight.
Are you talking about Piaget's concept of "object permanence"?
That a child understands that things and events continue to exist even when they can't see or hear them, we say that the child has developed object permanence. Object permanence is an important milestone in cognitive development, and it typically occurs around 8 to 12 months of age.
To understand how a child develops object permanence, psychologists have conducted research using techniques such as the "A-not-B" task. In this task, an object is hidden under one of two locations (A or B), and the child is expected to find it. Initially, when the object is consistently hidden at location A, the child will search for it there. However, if the object is then hidden at location B while the child is watching, a younger child may still search for it at location A because they have not yet developed object permanence. They are focused on what they saw last. On the other hand, an older child who has already acquired object permanence will search for the object at its new location (B) because they understand that the object still exists, even though they couldn't see it being moved.
To summarize, the understanding of object permanence in children refers to their realization that objects and events continue to exist even when they are not directly observed. This understanding is typically achieved around 8 to 12 months of age and can be assessed through tasks like the "A-not-B" task.