The Wii Fit has an interesting approach to improving and measuring your balance. It’s a two stage process. First, you train, on various exercises and minigames, doing things that improve your balance. In the artificial neural net side of Systems Science, we call this the ‘training set’, and if you think about it, the Wii Fit is training a real neural net, the three pounds of jellied neurons you carry at the top of your spinal column. The yoga exercises improve your static balance — the ‘Tree’ and ‘Half Moon’ poses, for example. Dynamic balance is through the strength exercises (‘Single Leg Lift’), or through true games (‘Penguin Slide’). Once you have trained up, you are then tested, but not on the things you trained on, instead, you have a ‘test set’, of exercises that are mostly unlike any of the games. Examples are the ‘Basic Balance’ test, and the measurement made whenever you run a body test. This is a good approach, I use something like it to train artificial neural nets, but the Wii Fit implementation leaves something to be desired. There’re two problems that I have encountered so far, response time, and lack of a trainable baseline.
The response time is a minor problem because it is only noticeable in a couple of the games — the ‘tightrope walk’ between two buildings, and the ‘walk your bubble’ down the stream games. In the other games, the character on screen responds more or less instantly to your weight shifts on the balance board. In those two, there is a noticeable delay, probably programmer-induced, between movement and action on the screen. The problem with this is that it’s teaching you the wrong thing. It’s teaching you, the system, to respond to what you think your body’s going to do, not to what it’s actually doing. This is a good idea for a pilot — you want to stay ahead of the aircraft — but not for inculcating basic balance skills.
The second problem is even worse, since it pervades all of the games and exercises. When you train on the Wii, you never get to evaluate your balance against an absolute measure, it’s always against where you were when the exercise started. You do get to see your absolute balance in a number of places, but nowhere that it does you any good. For example, every time you move to a new game, there’s a brief period where a green fuzzball moves around on the screen. That shows where your balance is, using the balance board as an absolute frame of reference. However, the display only lasts a second or so, and you don’t have a chance to get into a truly balanced position to see what it feels like. You also get to see your absolute balance during the initial phase of the body test, and during the ‘Basic Balance’ test, one of the tests that the Wii has selected just for you. In the first case, it’s only for a few seconds. It’s longer in the second test, but you have no control over when you are given that test, it appears at the whim of the Wii gods, and you can’t rerun it.
All the training exercises measure relative balance — relative to how you were standing when the exercise started. They have these little yellow circles, and your little red balance point moves around as you shift your balance, that little red dot starts in the centre every time. You can see this best in the basic breathing exercise, or in the Half Moon. No matter how far over you are leaning, your red dot comes up in the centre of the yellow, every time. Try it. Start the breathing exercise, and make sure all your weight is on one foot. See? Not only does this not give you as much useful information as it might, it can throw you off if it takes you longer to settle into a position than the Wii thinks you should. A brief wobble at the wrong moment will make the Wii think you are leaning well away from where you should be.
While the underlying approach is good — you don’t want people training to the test — the implementation is frustratingly flawed. It’s like training a ANN to find the global maximum, but lopping off the top ten percent of the fitness function. What Nintendo should do is have one exercise, Basic Breathing is my suggestion, that lets you stand on the balance board and see how far off centre your actual balance is.