Answer:
his perception of depth has changed, he has realized that if he crawls along the cliff he may likely suffer a fall.
Explanation:
His behaviour was based on  experimental findings of  Visual cliff  hypothesised  by  Gibson and Walk;  that dept perception is inborn or innate and not acquired.  The fact that  he was  not able to crawl across the visual cliff, at 10 months  contrary to his ability to  do so at 6 months, is an indication that  his  perception of  depth,  has changed.  The evidence that he achieved this  at 6 months without hesitation shows that the use of his sense of vision  to perceive  depth  is innate, and not acquired.
