"Speed" can be defined as: the relative swiftness of motion, rate of movement, velocity. Some people have tried to convince me from time to time that speed is not an important attribute in Wing Chun - but I believe that it is *vital* if you meet a relatively fast opponent. In my opinion, it is also contingent on the situation and type of fighter you are facing. Sometimes you can survive if you intercept a faster attack - but sometimes you may run the risk of being struck.
For Wing Chun Kuen purposes speed, as one of several physical attributes we need to develop as fighters, is composed of several factors including starting position of attacking limb, and also reaction and reflex times. Let's go with a definition of "reaction time" as a measure of the interval of time from the arrival/recognition of a rapidly presented and unanticipated signal (visual or tactile) to the start of the response to it.
For Wing Chun Kuen purposes, reaction time is from the start of your opponent's movement to the start of your reaction. This may relate to the information processing speed of your brain - you have to recognise the stimulus, decide how to respond to it then initiate your response. Well taught Wing Chun Kuen teaches reflexive response i.e. minimising or eliminating or, at worst, reducing your cognitive decision making time through the drilling of automatic responses into the gates being threatened and a simultaneous attack or turning of the opponent's attack against them.
Your reaction time does not equate with your movement time - which is the time interval between the initiation and the completion of the move. Both reaction time plus movement time constitute your response time. Reacting and moving involve different processes. There are three stages in your information processing - stimulus identification, response selection and response programming (preparing for and initiating response). Speed can best be enhanced by focusing on the two factors: response selection and programming.
The simple take on enhancing response selection is to have limited (minimised) the number of alternative responses you must consider in a situation such as an attack - this means, and Wing Chun Kuen has done a lot of the work for us here already if we properly understand it - minimising the available trained alternatives to attacks through the different gates. One per gate is actually sufficient!! Martial arts which teach a variety of alternatives to attack scenarios are actually disadvantaging the development of their practitioner’s speed.
There is a law called Hick's Law which, in this context, can be stated as: as the number of available alternative responses increase so does the response time. In other words, the more potential responses you have to cognitively sift through in order to select a response the slower you will be. Whenever the number of reaction options doubles, the amount of information to process through a decision making process increases by one bit and choice response time increases a constant amount. More directly - increasing the number of alternatives from 2 to 4 (doubling them) increases response time by 150 milliseconds. Pretty quick, eh? Yes! But - a good boxer's jab is at least a half that - a great boxer's is less than a third of this (40 milliseconds to go 42 centimetres!) - so - bad news if you meet them on the street! Now just how fast can *you* react???? (Fortunately the average mug is not that fast but most reasonable fighters will be faster than 150 milliseconds with a close punch). What to do?
Choose techniques for which you have a natural propensity - high S-R (stimulus response) compatibility (bong, tan, gan and lan fit this description if done properly - i.e. they are close to instinctive movements). Experiments have shown such Stimulus-Response (S-R) compatible techniques can reduce the Hick's constant down to 17 milliseconds. That’s enough to save you! In addition, (you'll just love this!!!), experimenters have found tactile S-R compatible responses will improve your reaction time (Chi sau right on! Let’s *not*, however assume chi sau equates with real world fighting - it doesn’t!).
Also - simplicity of movement is a virtue on our side - research into response complexity has, not surprisingly, found more complex movements need increased programming time and so increase your reaction time (so - the simpler the technique the better - in Wing Chun Kuen's case the straight line says it all, excluding punches will beat parry/punch every time - i.e. the simpler the better, the fewer the moves the better). Performing a longer duration move (e.g. lap sau and punch/backfist type moves) increases response time so we're ahead of the game with a faster move executed later (given it has a clear unblocked path to target and we are not vulnerable to counter as we execute it) than earlier with a more complex (i.e. longer, therefore slower) move. The earlier you can predict what is coming the shorter your reaction time will be as anticipating incorrectly can add hundreds of milliseconds to response time but anticipating correctly improves response time by only tens of milliseconds - so unless you can predict very accurately, you are better off not anticipating. Wing Chun Kuen is also ahead of the game with attacks which must change midway in favour of making another new attack.
Also, in passing, it’s been my experience that the more punches past three the slower and less accurate they become in a real scuffle against a moving unwilling target (the ancestors apparently knew a thing or two when they focused on throwing three attacks in an attack). Of course, that is the principle of “sufficient redundancy” - but that’s another attribute of Wing Chun Kuen best left to discuss another time.