A freeze response happens in nature not merely with humans. There are instances when a animal is suddenly confronted by a predator and the animal just freezes. I have heard people try to explain the behaviour by saying the animal was hypnotised. In reality the animal had a freeze response. Sometimes in the wild it has been observed that a predator chases down its prey and when the prey is finally cornered, it will have a freeze response. It stops running, it stands there and sometimes it will even fall over. What is happening is that the animal percieves that death is imminent, that there is nothing more to do. Hence the animal produces endorphins to make the pain of death less intense.

Fight or flight:the ultimate book for understanding and managing stress. Gary R Plaford