Over the last several years, more and more martial arts practitioners have been looking at the 'flinch' or 'startle' response with a view to building on it, rather than fighting to overcome it.
I read a very good article over at The Way of Least Resistance on this topic. It's definitely worth a read.
There are several talented reality based instructors out there touting the flinch response and how to build it into attack response and defense. Most of the training is good. Tony Blauer's course is one such example.
The biggest single issue I have with flinch response training is that many instructors mistakenly believe that the flinch response used during practice is the one that you would instinctively revert to when surprised. It most often involves covering up and pulling back. This seems like the body's natural response to a surprise attack, but it is flawed. It's actually the body's instinctive response to a known surprise attack.
Known surprise attack??? What the heck does that mean?
That means you know an attack is coming. The attack may vary, you may not know exactly what's coming, but you know something is. The typically taught flinch response is a good sort of 'catch all' which minimizes the chances of injury and responds to a variety of variations within an attack. There's nothing wrong with this, except that it assumes you know you're involved in an altercation.
There is only one true flinch response. It's the one that occurs when you are taken off guard and completely by surprise. And it only happens once (per situation).
There's no point in trying to fight this one, it happens on an instinctive level. Learning to use it is another thing altogether. It is my theory that many traditional martial arts build on this instinctive response in the design of the techniques themselves. My study of this continues.
So, what does this instinctive response look like? More often than not, it includes a striking out, or pushing out at the perceived threat. Portions of the body will pull back from the threat, the body will curve away from an abdomen attack, or the head will pull back from a face attack.
The hands, however, will shoot out towards the threat, as if trying to knock it away or provide some sort of barrier between the threat and the body.
This is especially important to know and significant when it comes to knife survival. The conceal-ability of knives, and the nature of knife attackers, increase the odds of a surprise attack. It is therefore essential to recognize what the flinch response is, what it looks like, and how to use it to your advantage.
Any realistic knife survival training needs to work on this. It is incumbent on instructors to have an understanding of this and to research the flinch response.
One of the advantages of this instinctive response is that it naturally transitions quickly and easily into realistic knife survival skills. One of the areas where I agree with mainstream thinking for knife defense is that gaining control of the knife of the knife bearing limb is crucial for survival. (There are exceptions, of course, but in general the thinking is sound) The beauty of the flinch response is that your body's natural reaction puts you exactly in the position to do just that. The vital areas of the body have been protected, or moved out of range, but your hands are touching or are very close to the threat.
On this level, there is no point in trying to override thousands of years of evolution. The flinch response occurs on a unconscious level, so you may as well let nature lend a helping hand.
I encourage everyone to learn about the flinch response and to make sure that training takes this into account. Due to the one-time nature of the instinctive response, it's important to understand how you will react when taken by surprise. That way, you can drill responses from the position you're most likely to find yourself in. I don't want to discount any system or teachers out there, but some instructors have applied a conscious pattern of thought in coming up with what they believe would be the instinctive response to an attack. The truth is, it all occurs on a more basic level, and it happens faster than the cognitive mind can process.