Your favorite athlete  closes in for a victorious win. The crowd holds its breath, and, at the crucial moment, she misses the shot. That competitor just experienced  the phenomenon known as "choking," where despite months,  even years, of practice, a person fails right when it matters most. Choking is common in sports, where performance often occurs  under intense pressure and depends on key moments. And yet, performance anxiety  also haunts public speakers, contestants in spelling bees, and even world-famous musicians. Most people intuitively blame it on their nerves, but why does being nervous  undermine expert performance? There are two sets of theories, which both say that primarily, choking  under pressure boils down to focus. First, there are the distraction theories. These suggest that performance suffers  when the mind is preoccupied with worries, doubts, or fears, instead of focusing its attention on performing the task at hand. When relevant and irrelevant thoughts  compete for the same attention, something has to give. The brain can only process  so much information at once. Tasks that challenge working memory, the mental “scratch pad” we use to temporarily store phone numbers  and grocery lists, are especially vulnerable to pressure. In a 2004 study,  a group of university students were asked to perform math problems, some easy, others more complex  and memory-intensive. Half the students completed both problem types with nothing at stake, while the others completed them  when calm and under pressure. While everyone did well  on the easy problems, those who were stressed  performed worse on the more difficult,  memory-intensive tasks. Explicit monitoring theories make up  the second group of explanations for choking under pressure. They’re concerned with how pressure can cause people to overanalyze the task at hand. Here, the logic goes that  once a skill becomes automatic, thinking about its precise mechanics  interferes with your ability to do it. Tasks we do unconsciously seem to be most vulnerable to this kind of choking. A study on competitive golfers compared  their performance when instructed to simply focus on putting as accurately as possible, versus when they were primed  to be acutely aware of the mechanics of their putting stroke. Golfers usually perform  this action subconsciously, so those who suddenly tuned in  to the precise details of their own moves also became worse  at making accurate shots. Choking may not be inevitable  for everyone though. Research suggests that some are more susceptible than others, especially those who are self-conscious, anxious, and afraid of being judged  negatively by others. So, how can we avoid choking  when it really counts? First, it helps to practice  under stressful conditions. In a study on expert dart players, researchers found that those  who hadn’t practiced under stress performed worse when anxious, compared to those who had  become accustomed to pressure. Secondly, many performers extol the  virtues of a pre-performance routine, whether it’s taking a few deep breaths, repeating a cue word, or doing a rhythmic sequence of movements. Studies on golfing, bowling,  and water polo find that short rituals can lead  to more consistent and accurate performance under pressure. And thirdly, researchers have shown that having an external focus  on the ultimate goal works better than an internal focus, where someone is tuned into the mechanics  of what they’re doing. A study of experienced golfers revealed  that those who hit chip shots while focused on the flight of the ball performed significantly better than those who focused on the motion of their arms. So, perhaps we can modify  that age-old saying: practice, under pressure, with focus, and with that glorious end goal in sight, makes perfect.