I recall reading a very interesting study on birth and pre-birth memories that people are able to access under hyponsis. Traumatic stuff is remembered most clearly if I remember correctly.
Depends upon the level of trauma. The human mind has the miraculous ability to hide from consciousness—sometimes extremely well hidden—memories which would reignite horror or anguish unendurable. A little child’s mind when conronted with a helpless situation will pour back over memories of behavior and adult reaction to that behavior, seeking to understand what the child can do to manipulate/change the current stress. But this is not confined to just little ones. Adult females are known to do this same thing and often it leads to the ‘stockholm syndrome’ in marriage for children and spouse, and acutely in the abused wife conundrum.