Anxiety and Arousal
So, the greater the gap between our estimated abilities and our perception of the task's difficulty, the more likely anxiety will negatively affect our performance. However, this does not mean that all anxiety is bad. Indeed, anxiety researchers often cite the "Inverted U" curve to illustrate the positive and negative relationship between anxiety and performance. The "inverted U" refers to the shape of a line on a graph when we measure and plot the relationship between anxiety and performance: anxiety on the X axis and performance on the Y axis (remember the X,Y graphs in geometry?). As anxiety increases along the X axis, so does performance along the Y axis, up to a certain point (imagine the top of the hill on an upside-down U) at which point as anxiety continues to increase along the X axis, our performance declines along the Y axis.
It turns out we actually perform better when we experience a little anxiety. This is especially true in sports and similar performance situations. Low to moderate levels of anxiety, over a short period of time, heighten our arousal in a beneficial way. This arousal makes us more alert and tasked-focused. It also serves to motivate us to rise to the challenge at hand. This increased arousal is due in part to the release of chemicals in the body such as adrenaline and noradrenalin. However, beyond a certain point, too much anxiety over a longer period of time actually begins to interfere with our performance. Our ability to concentrate diminishes as we shift our focus away from the task, and toward distressing bodily signals. Moreover, when anxiety overstays its welcome, exhaustion results. Human beings are not designed to perform well under these conditions. These physical changes are discussed in more detail in the section on the Biological Explanations of Anxiety Disorders.
The negative effect of too much anxiety is especially noticeable when the task is complex and requires our full attention. This often occurs when we are required to take a test (called test anxiety). When we become excessively anxious in a performance situation like test-taking, our attention starts to shift away from an outward focus on the task, toward an inward focus on ourselves. Subsequently, our attention becomes much more narrowly focused and we become increasingly alert to threatening cues in the performance situation. As a result, we are now susceptible to biases in our thinking and we may incorrectly assess, or appraise the situation (e.g., "I am doing horribly," "I will never get it right," etc.). As we will soon see, these cognitive appraisals heavily influence the degree of anxiety that we experience.
When our thoughts become disrupted in this way, we will usually try to cope with these distressing thoughts. Coping often takes the form of unproductive worrying. Worrying in this sense represents an unsuccessful attempt to control the danger at hand. Next, we begin to experience distress about our inability to control the worry from intruding into our minds. Because our mind is preoccupied with these intrusive thoughts, we have a hard time trying to access the information we need to complete the task successfully. This series of events creates a significant decline in our performance.