When going into a longsword bind, or getting hit as part of a Kata, I tend to flinch visibly and shut my eyes.
What are some exercises I can do, solo or with a partner, to help me keep my eyes open?
The flinch reaction is a nervous system reaction to a stimulus in order to protect a portion of the body inherently felt to be at risk. When your nervous system is repeatedly overridden (for example, when we repeatedly stretch past the point of basic resistance) the body relaxes and the signal to fire that reflex is no longer sent under that stimulus.
Therefore, the simplest way (and I say simple meaning "basic", not "easy") is to repeatedly expose yourself to the stimulus and consciously resist the urge to flinch. Performing waza (techniques) at a slow pace and building up speed can allow you an opportunity to convince yourself consciously that you can avoid that flinch response, and that you are in fact protecting that portion of your body (usually the eyes) that is felt to need protection. Ultimately, however, you need two things to happen:
Flinches are not, by and large, a bad thing. The response is, in fact, quite healthy. It can, however, be controlled, and this is the far better use – redirect rather than inhibit natural responses.
stslavik has the right idea. You need to dampen your current reaction so you can substitute another.
Martial Arts hoodoo talk:
You flinch because your mind gets caught on the idea of being hurt. If you can still your mind, your reactions will become more in line with your intent.
For me the thing that's helped most is visualization. As stslavik says, you need to repeatedly expose yourself to the stimulus in order to change it. Fortunately you can avoid actually getting hit, because visualization actually fires the same neurons that would fire in the real situation!
So find a "natural" (comfortable, easy to concentrate, etc) spot and visualize getting hit or getting into a bind. During the visualization, really concentrate on the idea of keeping your eyes open and staying focused. You may even feel an impulse to close your eyes or half-flinch while you're going through the flow in your head. Notice it, address it, and change it.
As @stslavik already gave an excellent answer, I'll just throw in an anecdote.
Not long after I started Judo, one of the more senior members of the club decided that he needed to cure my flinch that I had developed over being thrown. That evening he took me to the end of the mat and if my memory doesn't fail me, threw me solidly for at least half an hour. By the end of that time, I was tired and had completely given up fighting being thrown. That was the beginning of the end of my flinch.
Just goes to show that you can "train in" or "train out" muscle memory.
Following up from @stslavik answer:
Flinches are good. A controlled but instant reaction to a threat developed through muscle memory,
Flailing is bad. An uncontrolled reaction to a threat that will likely get you hurt.
Obviously, closing your eyes is "A Bad Thing", and that comes from you not trusting your blocking or your footwork (say, from a standard tsuki punch to the head) from stopping or missing the fist. This is quite natural!
With the aid of a good training partner, they can drill and repeat the punch to you while you practice and improve your (in this order):
Your partner needs to try to hit you! No flouncing about with punches that are 6 inches short of your nose (that's called dancing!) But, with practice, you'll start to internalise the movement so it becomes less of a shock and more controlled until you get to that "controlled twitch" state.
With a bit of luck, you will get hit a few times, but it will be a graze and you'll laugh it off.
This happens as a natural reaction but you can train to 'disable' this reflex.
stand without defending while a colleague performs strikes(straight punches for instance) very close to your face and focus on not blinking.
with large(boxing or kickboxing gloves) cover up when receiving punches and keep your eyes on your opponent through between your arms/gloves, don't flinch when hit.
sparring with light contact to the face will remove some or all of the subconscious fear in time as you get used to getting hit sometimes.
Flinches are caused by fear and fear is caused by:
The first one applies much more often than you'd think.
The second and third apply when you're training with opponents that are too novices to actually control their rhythm and strength in order to help you learn.
I find that cyclic exercises may help much. If you're practising a sword for example it could be something like that:
Those are just examples you can adapt to your art of choice. Keep in mind:
Example of how it should feel (empty handed): http://www.youtube.com/watch?v=rcwccwO57UQ (jump to the middle of the video)
I've done some studying with Tony Blauer and I'm also a Personal Defense Readiness coach in his program. We use Emotional Climate Training to do what you describe. In this case it i more of converting the natural flinch response to a tactical response.
Adding some information on Emotional Climate Training (too long for a comment).
Okay, Emotional Climate Training (ECT) is a six stage drill used to help convert the startle/flinch response into a tactical response. Drills are done at a safe speed and under control. The various stages are designed to wean the initial startle flinch, progressing to identifying pre-contact attack cues, identifying safe/unsafe moments during the attack, and finally taking the trainee through the primal SPEAR tactic (think cover and protect yourself), the protective SPEAR (pushing away danger), and finally the tactical SPEAR (launching at the initial stage of the attack to intercept and counter the attacker. Hope this gives a little more detail about ECT. It is a lengthly process but you can use it in any attack scenario (haymaker punches, tackles, kicks, etc,).
Repetition will help reduce the reflex of flinching. Another tip is that I used to train with a bunch of Indonesians in 'Silat' and their advise was a drill they usually do to avoid flinching.
Basically they would stand waist deep in water, whether a pool or the sea, and started to punch or hammer fist the surface of the water. They try their best to keep their eyes open when the water splashes on their face. My eyes were sore due to the salt water but i swear these guys doenst even flinch when getting punch in the face.
I practice this whenever i can.
There is no way that you can override the Flinch or Spinal Reflex, it is activated by the fact that your System is surprised, training the same situation until you are no longer surprised by it is not the same as controlling your Spinal Reflex action, you quite simply knew what was coming so it did not surprise you. All these threads that talk of controlling the spinal Reflex Arc make the same mistake, and this could lead to a dreadful beating if you think it will work in a situation that once again surprises you.
I have been in the M.A. for over 50 years and have heard all this before, trust me your training will have no effect on something your Conscious Brain does not register. And before any one goes off at me about using your Sub - Conscious Brain if you do activate an action Sub-Consciously it is no longer you in Control, still not your training method just a Spinal Reflex in itself.