The speed-accuracy trade-off
This is an excerpt from Fundamentals of Motor Behavior by Jeffrey Fairbrother.
You have probably experienced speed-accuracy trade-offs many times as you have completed various tasks (Fitts, 1954). For example, you know from experience that the faster you move your computer mouse, the more likely you are to miss the icon you are moving to click. Similarly, you also know that you need to slow down to ensure that your key goes into the lock when you want to open your front door. Both of these examples demonstrate the fact that many tasks require us to trade between speed and accuracy in our movements. This is usually not a problem until we are faced with a task that gives us a limited amount of time to respond. When we are compelled to act quickly, we can sometimes emphasize speed over accuracy and actually end up missing the goal of the task entirely. For example, think about how many times you have hurriedly reached to flip a light switch as you passed by it without slowing your stride. Because you knew that you had one short opportunity to hit the switch, you probably emphasized speed and in some cases missed the switch completely. What I find interesting about this particular situation is how our perceived need to act fast often initiates a cycle of several reaches and misses, which ends up taking far longer than if we had simply slowed down in the first place.
Sometimes, however, we might favor accuracy over speed. This might happen when we are just getting the hang of a skill. Because we cannot complete the skill quickly, we tend to focus on just getting it done. This can be problematic if there is a limited amount of time to complete the task. For example, a beginning music student might methodically work his way through all the notes of a song only to realize that his slow pace did not result in a recognizable tune. I've used a speed-accuracy trade-off activity in my classes for many years and have seen some interesting behaviors. In my experience, certain people have a very difficult time trying to balance the speed and accuracy demands in a task that requires them to tap back and forth between two targets. Some people cannot seem to slow down even though they continually miss the target, while other people move so slowly that it stretches the imagination to use the word “speed” in connection with the task they are supposed to be completing.
Many tasks have both speed and accuracy requirements. Often the best way to approach these tasks is to try to move as fast as you can without sacrificing accuracy. This might apply to taking a shot on goal in a hockey game or swinging a cricket bat. Both of these examples illustrate tasks that must be completed quickly but that depend on a high degree of accuracy. After all, it does not matter how quickly you can kick a soccer ball if you always miss the goal. If, on the other hand, you are usually very accurate when you complete these types of tasks, you might try speeding up a bit to gain a greater advantage. If you miss your target too often, then you should slow down.
Sometimes moving faster can make you more accurate. Although the general rule is that we trade speed for accuracy (or vice versa) when we make aiming movements, there are a couple of exceptions. Dick Schmidt and his colleagues have shown that when we move very rapidly to begin with, speeding up can make us more consistent in timing a movement (Schmidt et al., 1979) and in where we end the movement compared to our target (Schmidt & Sherwood, 1982). This research suggests that faster might be better if the action requires us to move rapidly in the first place. For example, you need to swing an axe quite forcefully if you want to chop wood, so working to improve the speed of your swings might increase the accuracy of your blade placement on the tree or log. This does not mean, however, that you should go out and swing as hard as you can. Such a strategy would likely result in sloppy and very dangerous performance. Instead, it means that you might improve your accuracy if you work to gradually increase the speed of well-controlled swings.
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