If you’ve ever "choked" before a big test, speech, or presentation, you’ll appreciate the results of a new study. Stress – or, more precisely, the stress hormone, cortisol – influences our performance in a big way. This part is not surprising. What is surprising is that there’s a complex interaction between stress, working memory, and our level of anxiety about the type performing we’re about to do.

One type of choking happens when we are literally distracted by our anxieties, which hijacks our attention, or brain power, away from the task at hand. Another type occurs when we are overly focused on all the facets of our performance, so we become self-conscious about it.

The current study looked at math test anxiety in college students, since this subject commonly inspires anxiety in people. The researchers measured stress (via saliva cortisol levels) in undergraduates both before and after they took a stress-inducing math test. They also measured their working memory, which is the "short term system" that we use when we’re problem-solving; another way of thinking about it is that it’s a mental reserve of all the tools needed to process a problem at hand. Lastly, the researchers measured how well the students did on the test.

The team found that people with low working memory (those who used relatively less mental reserve to process problems than others) were not affected by cortisol levels, which was not surprising. But for people with greater working memory, higher cortisol levels led to either a boost in performance or a freeze, depending on their feelings (anxiety) about math. Specifically, people who were not anxious about math did much better on tests when their cortisol level was higher. But for people who did experience math anxiety, the higher their cortisol level, the more likely they were to freeze up during the test.

Lead author Sian Beilock explains that it’s all about how we interpret our physiological responses that determines our performance. "Under stress, we have a variety of bodily reactions; how we interpret these reactions predicts whether we will choke or thrive under pressure," Beilock said. "If a student interprets their physiological response as a sign they are about to fail, they will. And, when taking a math test, students anxious about math are likely to do this. But the same physiological response can also be linked to success if a student's outlook is positive."

So how do we shift our interpretation of our anxieties? In another paper published this month, Beilock and her team outlined the various types of "choking" that can occur, and the mechanisms that underlie them. One type happens when we are literally distracted by our anxieties, which hijacks our attention, or brain power, away from the task at hand. Another type of choking occurs when we are overly focused on all the facets of our performance, so we become self-conscious about it.

Depending on the type of choking that you experience, the solution will vary. Test anxiety can be beat by writing down your anxieties before the test, which essentially frees up that brain power so it can be focused on the test itself. On the other hand, "[w]hen you're worried about doing well in a game, or giving a memorized speech in front of others," Beilock says, "the best thing to do is to distract yourself with a little tune before you start so you don't become focused on all the details of what you've done so many times before. On the playing field, thinking too much can be a bad thing."

The more we understand about how anxiety works, and can alter the performance of otherwise capable people, the better equipped we’ll be to combat it with effective new methods.

Beilock is a researcher at the University of Chicago. The first study was published in the June 27, 2011 online issue of the journal Emotion. The second study was published in the August 2011 issue of the Journal of Experimental Psychology.