Well let's give this an example, let's say our predator is a serial killer, and a random person is the prey. In this certain, not every situation, maybe some, but lets say it's this certain situation. This person is in his/her house, inside his/her bedroom, kitchen, basement, etc. And then the predator stalks his/her prey, slowly and quietly, while the prey is ever so oblivious to it's surroundings. Well in this situation the predator strangles its victim. Through the strangling the prey either can perform tonic immobility, as in faking as if it were choked to death, to trick the predator that he/she has taken it's victim's life. Or either to fight back, or simply just die. But once in tonic immobility, he/she has tricked the predator, therefore can escape, or fight back.