I think the main purpose of self-defence is over-coming this freeze instinct. I think the freeze instinct is the first one that develops (I've experienced it a few times when I was younger). However I think even with very simple training (even just on your own) you can adapt this to a response) - before doing aikido I used to just do some boxing style striking practise on my own. This response was the first thing I did when I was attacked at school and it was suprisingly effective even though I had done very little.
I think the flight response is maybe a secondary response when you have already been attacked and you have a moment for your subconcious to consider that you are not going to survive the situation - I've never experienced that response.
Now I have a 'fight' response, but unlike the striking response I had when I was young it tends to be a avoid/'technique'/pacify response which I think is far better for both parties. (When I say technique, in reality many of these have been half techniques in that I've utilised a standing pin or just held someone from behind after a frontal attack).
For me our responses are what we are training because it is very difficult to think through techniques in real situations. Luckily as aikidoka we are training in minimally damaging responses so we can have confidence in defending ourselves whatever the situation (whether it is a friend or stranger).