About a month ago I posted a very short excerpt from a book I had just completed titled "How We Learn to Move" by skill acquisition specialist Rob Gray and now with some AFLW winding down I can finally start posting the numerous noted I took from it.
I'm sure you'll get plenty our of the notes on their own but if you don't have a decent background in this theory of movement, then I strongly suggest you get your hands on the actual book.
Here's part 2 of 97 book notes and over 4300 words in this series.
CHAPTER 4 – FREEDOM THROUGH CONSTRAINTS?
The answer to the problem of too much choice/degrees of freedom is to take away some options.
A constraint is something that eliminates certain possibilities or options for action.
Everyone has different individual constraints, such as the player who can kick on both sides of the body that has the option of going left or right on a defender, where a 1-sided player has only 50% of these options – constraints change the movement solutions available to us.
Environmental constraints are properties of the world around us (gravity, wind, temperature, surface etc).
Task constraints are factors highly specific to the skill being performed such as training against no opposition vs playing against opposition – you now have far more constraints to work around as you perform the the same skill.
When we first learn a new movement skill, we constrain ourselves naturally through a process called freezing degrees of freedom, where we rigidly fix degrees of freedom by not using particular joints/muscles as we don’t know how to integrate them yet.
A coach can give instructional constraints (you’re the left winger so stay on the left part of the ground etc), that quickly serves to prevent all players swarming around the ball.
The method of amplification of errors is a constraint manipulation that takes a slight “flaw” in a movement pattern and making it much larger and louder to the perceptual system of the performer.
You can also add constraints through appropriate manipulation of the task constraint of equipment, such as junior football players playing games on smaller grounds, with less player numbers and a smaller footy.
Another way that constraints can be manipulated to create action opportunities for a performer is by changing their individual constraints through appropriate strength and conditioning training such as goal keepers with quicker movement times consistently waiting a bit longer before starting to block the shot, subsequently getting more information about where the shot was likely to go before trying to block (less guessing).
Constraints can also be manipulated to aid self organisation and skill acquisition by introducing variability and some essential noise as we’re not trying to develop 1 ideal technique, but to be adaptable and flexible so that we can use different movement solutions to achieve our goal in the face of ever-changing conditions.
Moving skillfully involves coming up with new solutions to new problems, not just by repeating the same old solution.
Think of constraints as informative boundaries that guide self organisation by pushing performers away from certain solutions and encouraging them to look for others while providing information for them about how they should change how they are moving.
CHAPTER 5 – WE PERCEIVE THE WORLD IN TERMS OF WHAT OUR BODY AFFORDS US
Our perception of the world changes depending on our ability to act within it.
Perception of our environment is not solely based on its physical properties, rather perception is embodied, where the information we detect about size, distance and speed of objects is scaled by our ability to act on these objects.
This embodied perception approach to perception argues that what we perceive is not a true representation of “what is out there” but rather what reflects our ability to act on objects in our environment.
Interesting studies have been done on people’s ability to judge the slope of a hill where the same hill walked up on your own vs with a 20kg back back are perceived way differently. If you’re young and strong then the added load may have you perceive the slope as maybe 20% harder but if you’re older and weaker, then it may be perceived as 80% harder.
Experienced athletes have a memory store of different plays and then they match the current situation to an old but similar one, which can give you a quick checklist of what’s worked in this situation before, what hasn’t and what your options are.
For a performer, gaps don’t look wide, opponents don’t look near and pitching throws don’t look fast. Instead, performers see pass-through-ability in a gap, tackle-ability of an opponent and hit-ability of a pitch.
Affordances have to be measured to the individual as they are unique to that individual.
When we pick up information of the world, we need to somehow incorporate our own action capabilities which is usually not much of a challenge such as searching your crowded basement looking for the fuse box and the main affordance your using is pass-through-ability in reference to thinking “Can I pass through the gap in those boxes?”, “Do I need to go sideways or do I need to rotate my body to do so?” The perception of what is possible is different between thin and bigger people because our perception is well calibrated our action capacity.
Relating our perception of the world and our action capabilities is an ongoing process and it must be because as we grow our dimensions change, we get fatigued and our movement changes.
In a rock climbing study they found that climbers with less grip strength simply looked for the route with the largest holds where climbers with greater grip strength had a far less predictable gaze pattern as they could view a wider range of possibilities that they could act on as no hold was unattainable for them.
Our perception is embodied – our physical capacity is shaping how we view the world and when it is not very large, we see only the limited, predictable opportunities for action but when it is large, it opens a whole new set of affordances for us. We see the world like this because it directly supports our ability to act in our environment.
Embodied perception supports action selection so when a pitch is more suited to my goal of hitting to my an area where I can run a base, then I perceive the affordance as hit-ability, which makes the ball look bigger and makes me more likely to select an action of swinging.
Embodied perception supports an action selection process that helps reduce our energy expenditure and keeps us from becoming overly fatigued.
The constraints of our environment shape our perception of it in terms of the task we are given (the direction we are asked to hit the ball), the environment we act in (whether we can choose between stairs and an escalator) and is embodied in terms of our individual constraints (the length of time we have dive to the corner of a soccer net to stop a goal kick).
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