It is very common to hear about the 'flight or fight' response to danger, however many survivors experience immobility or a 'freeze' response during an assault. The 'freeze' response is identified in more than 1/3 of adult rape victims and in half of childhood sexual abuse victims.
When we are in danger, the part of our brain called the amygdala will respond instinctively to ensure our survival. This part of our brain is not concerned with the later affect of this response (which for many can cause post-traumatic stress disorder) but is only concerned with immediate protection.
If an individual reacts by shouting or screaming, they are likely to increase the likelihood of severe injury or death. This is why a lot of victims will subconsciously react with passive defence. Freeze is projected to cause the perpetrator to back off. If this fails a victim may move immediately to ‘flop’ in their response- muscular tension will drain away. The less tension in our muscles the less likely we are to sustain physical injury. At this point, victims may become very dissociative. If no physical escape is possible they internally escape which is a useful survival mechanism.
If you reacted this way during an assault, know that it was not your fault. You had no control over how your brain reacted to the danger you were in. You did not want to be raped or sexually abused.