"I did it 10 times in a row at home. Honest!"
Has this ever happened to you? You've been working on a really impressive trick at home. After lonely weeks of ardent, dedicated, agonizing practice you finally have it mastered. Now it's time to dazzle your juggling buddies. You say, "Hey, watch this!" Then, with all eyes watching, you fail miserably. Oh sure, you get it after the third or fourth try, but by then no one's looking.
Why does this happen? How come "it never works when you watch?" Was it that you didn't practice it enough? Probably not. After all, you did do the trick 10 times in a row.
According to motor learning research, your problem is not lack of practice, but something called "conditions of practice." This has to do with such things as your practice environment and how you distribute your practice time among different tricks. You may find it surprising that, "...the amount of practice is not the critical variable influencing motor skill acquisition." (1) Many other factors interact with practice to affect learning and performance.
Recently, there have been some exciting findings on making the most of your practice time. Researchers have looked at whether it's best to concentrate on a single trick ("blocked" practice) or to work on several tricks in each session ("mixed" practice). Here it's important to remember the difference between learning and performance. Experimental results show that "blocked" practice improves performance in the actual practice session, but "mixed" skill learned through "mixed" practice is more easily transferred to another context, such as a performance situation.
Why is "mixed" practice better than "blocked" practice? It's thought that practicing several tricks in a single session improves learning because of the mental "interference" of one trick with another. Each time you switch tricks, you have to partially rethink how to do the next trick. This brief mental rehearsal enhances learning. On the other hand, you don't go through this process if you are practicing the same trick for the whole session. For this reason it's best to practice in a "mixed" fashion to optimize learning and performance reliability. In fact, Magill (1) gives the practical suggestion that high levels of "interference" could be achieved by trying all variations of a specific trick in each session.
Perhaps the main cause of the dreaded "it never works when you watch" effect is your practice environment. Do you always practice alone? Do you always practice in the same place? Do you always practice at the same time? Well, don't!
Motor learning experts will tell you that your surroundings, and even subtle factors such as your clothing, should be varied in order to develop performance reliability. This means you should try to juggle your practice space as well as your props. Also, if you want to become solid at a trick in a performance situation, you need to practice the trick in front of spectators. Certainly this is one of the benefits of attending a juggling club meeting instead of practicing alone.
While reading these articles, you may have wondered why this information isn't common knowledge. Why didn't your physical education teacher tell you this stuff in high school? Well, the main reason may be that the field of study is very young. Although the earliest research into motor learning can be traced back to the 1850's, it was not until 1971 that a comprehensive testable theory of motor learning was developed (2). In fact, most of the research findings I've presented are post-1971.
Much is still unknown. For example, another "condition of practice" which
could affect learning is the length of your practice session. As yet there's
not much solid information on this, but research is continuing. Someday we
might even understand why it works best of all, no matter who's watching, when
you hold your mouth just right!