This is an excerpt from Attention and Motor Skill Learning by Gabriele Wulf.
What it is that makes people choke? Some scientists believe that pressure to perform well creates distractions (e.g., Easterbrook, 1959; Wine, 1971; for a review, see Baumeister & Showers, 1986). That is, individuals tend to either miss cues that are relevant for the task or focus on things that are irrelevant to the task, including worries about their performance and the possible consequences. Such distracting thoughts are assumed to be the reason for poor performance under pressure. While distraction might be one factor responsible for these performance decrements, there is also evidence that choking is the result of people's becoming self-conscious and too concerned with the step-by-step execution of the task (e.g., Baumeister, 1984, 1985; Lewis & Linder, 1997). Self-focused attention is assumed to disrupt the automaticity in movement control that typically characterizes skilled performance. As a consequence, performance suffers or breaks down completely. Richard Masters (2000; see also Masters, Polman, & Hammond, 1993) termed this idea the “conscious processing hypothesis.” The use of conscious control processes induced by stress, anxiety, or pressure to perform well reflects a temporary regress to earlier stages of learning (Pijpers, Oudejans, & Bakker, 2005), in which performance is rather volatile.
Some experimental evidence for this view comes from the baseball simulation study by Gray (2004). Gray looked at the number of judgment errors that expert batters made regarding the direction of the bat (up or down) when a tone was presented. He predicted that participants would make more judgment errors when they were in a good phase of batting performance and fewer judgment errors when they were in a batting slump. This interesting prediction was based on the assumption that, when the movements are controlled automatically and performance is at a high level, individuals should not be aware of the details of their movements (see also Beilock & Carr, 2001); therefore, judgment errors should be higher. In contrast, when individuals were in a slump, the perceived pressure to improve performance was expected to result in increased self-consciousness and a more conscious mode of control; as a consequence, it was assumed that judgment errors would be reduced. This is indeed what Gray found. There was a significant positive correlation (r = .89) between the number of hits and judgment errors. This indicated that at high levels of performance, the batters paid less attention to the details of the execution of the skill. When they were in a slump, however, self-focused attention increased, presumably as a result of attempts to improve. Of course, it is also possible that the slumps were created by an increase in self-focused attention that occurred for some other reason. Whatever the causal factor, though, it is interesting to see that good performance is indeed associated with less attention directed at the details of that performance.
Interestingly, it does not seem to matter whether an individual perceives pressure to improve based on his or her current performance or whether the pressure is induced by some external source. In another experiment, Gray (2004) created a pressure situation by informing participants that they would receive $20 if they were able to increase the number of hits by 15%. This condition resulted in poorer batting performance and lower judgment errors (with regard to the direction of the bat at the time a tone was presented), similar to findings from the previous experiment in which the pressure was self-induced. Importantly, Gray also showed that movement coordination was affected by the pressure. In particular, he looked at the variability in the time ratio of the windup (i.e., the time when the batter's lead foot is in the air) and the swing phase (i.e., the time from initiation of the bat swing to minimum bat height). When performance is consistent and at a high level, and the movement is controlled automatically, variability in this ratio is low. However, with the additional pressure created by the prospect of winning extra money, variability in the movement pattern increased significantly. This nicely shows how the regression to a more conscious type of control—induced by pressure to perform well—degrades the fluidity of the motion and makes the outcome less reliable.
Anxiety can have effects on motor coordination similar to those from pressure to perform well. Studies have shown that situations that cause anxiety lead to less fluent and efficient movement patterns; this is also reminiscent of coordination patterns that are seen early in the learning process (e.g., Beuter & Duda, 1985; Weinberg, 1978; Weinberg & Hunt, 1976). In a recent study that used a climbing task, different degrees of anxiety were induced by having participants traverse a wall at two different heights (Pijpers, Oudejans, & Bakker, 2005). Even though the two traverses were identical in terms of the holds for the climber's hands and feet, the higher traverse clearly induced more anxiety (as measured by an anxiety questionnaire and heart rate). As a result, participants performed more exploratory movements (in which a hold was touched without being used as support), maintained longer contact with the holds, and moved more slowly between holds, increasing the total climbing time. Thus, the fear of falling created by the greater height seemed to result in more hesitant behavior and more conscious, step-by-step control.
This is an excerpt from Attention and Motor Skill Learning.