J. mcvicker hunt began a program of tutored human enrichment in an iranian orphanage. this program trained caregivers

Imitate babies' babbling                        

Explanation:

The answer is --- Imitate babies' babbling.

Joseph McVicker Hunt was a famous American author and educational psychologist.  He encouraged and researched concepts that is related to  malleable behavior of a child intelligence.

In  the Iranian orphanage, Joseph McVicker Hunt trained  caretakers about the human enrichment to imitate the babies' sound or murmuring.

babbling is a stage in the young children where babies create or experiments with any articulate sounds but does not mean any recognizable words.

Thus the answer is ---

Imitate babies' babbling

answer; biological;