Stimulus-Response (S-R) Compatibility is usually defined as the ‘naturalness of the connection between the stimulus and the associated response'. Reaction Time for skill performance is faster the more compatible the S-R pairs.
For example, the S-R Compatibility for turning a car steering wheel to the left in response to an upcoming left turn stimulus is very close. This is not the case for a person placed for the first time in a sailing boat who is asked to turn the boat to the left - they generally will have a short “incompatibility delay” while they work out that the tiller needs to be moved to the right in order to turn the boat to the left.
Practice and High-Level Performers
A highly practiced performer can overcome many things, including the disadvantage of many S-R choices and low S-R Compatibility. For example the skilled sailboat racer almost instantly moves the tiller to the left as soon as it is obvious he needs to turn the boat to the right.
Research has shown that both the amount of practice and the nature of practice can effect Choice Reaction Time. With extreme amounts of practice, high-level performers can produce reactions that approach automatic processing; not only are these reactions very fast, but they are slowed down little, if at all, as the number of S-R choices increases.
That’s the good news: S-R Non-Compatibility can be overtrained and therefore compensated for. The caveat, of course, is that long-term training is required for this overtraining to occur. Short-term practice, such as is needed in occupational training contexts rather than lifestyle training contexts, may not provide the over-training needed to compensate for S-R compatibility bias.
Natural Defensive Gestures and S-R Compatibility
Consider how a person naturally responds to a sudden stimulus, such as a splash of water aimed at their face..... Now, consider (if you have experience of it) how some Self-Defence training attempts to teach how a practitioner “should” block a punch. Often the “natural” response to the stimulus is seen as somehow less-optimal than a neater, more technically alluring or complex movement, however what the sport-science is telling us is that if the “blocking move” does not closely match the naturally-connected response, then the Reaction Time will be longer.
Needless to say, in the case of a punch to the face, a longer Reaction Time carries serious risk. What then is the most naturally-associated response to a punch in the face?
Cell Press, in an article in 2004 noted new research which was being published on the machinery of that automatic, natural response called the startle reflex; “...a critically important protective mechanism by which animals and humans instantly protect themselves against threats ranging from an attacking predator to an incoming golf ball.”
For some years, a scientist called Graziano has been studying in a number of experiments how certain movements, consistent with defending the head or body from impending threats are automatically evoked. These movements include: “a squint and facial grimace that was more pronounced on the side of the sensory receptive field, a turning of the head away from the side of the sensory receptive field, a rapid movement of the hand to an upper lateral location as if blocking an object in the sensory receptive field, and a turning outward of the palm”.
He went on to note that “These movements had a machine-like repeatability over hundreds of trials” suggesting that they are highly reliable and do not atrophy over time. He also asked whether there might be a stored set of postures in the brain which controls limb-movements to evoke these inherited defensive gestures.
Pahlavian, researching similar fear effects and publishing his findings in 2000, found similarly: “...stimuli such as pain or fear automatically elicit patterns of terminal motor states corresponding to fight or flight, initiating processes of preparation of spatially oriented movements which are automatic”
Critically, these movements are extremely fast: "For a protective movement in which the hand moved to an upper lateral position and turned outward as if to block an impending threat to the head, the velocity was remarkably fast, appropriate for a defensive gesture (230 cm/s at peak speed...)" [from Graziano]
So, it would seem, that incorporating natural defensive gestures into our Breakaway and Self-Defence training programmes may indeed be a way to overcome some of the issues with improving Technique Recall, Performance Effectiveness and reducing Choice Reaction Time.