There is a long research tradition studying the gross response of our nervous system to stimuli as a result of a response in the Reticular Activating System of the brainstem. The general response seems to be one of preparing us for activity since it involves increased heart rate and blood pressure and a condition of sensory alertness, mobility and readiness to respond. Still, too much of a good thing apparently is not so good.
The venerable Yerkes-Dodson curve (sometimes referred to as “The Inverted-U”) describes performance vs. arousal in a way that shows performance being degraded under extremes of arousal, and this relationship indeed does seem to apply fairly widely.
That’s the high school textbook picture, and it’s accurate for the most part. Still, in real life, upon closer inspection, arousal is a very complex phenomenon involving a number of different neurotransmitter systems in the brain and affecting different kinds of skills in different ways. For one thing, it doesn’t seem to apply equally to different activities. For another thing, it doesn’t seem to apply equally to different people. But on average, it holds up fairly well.
During the Civil War in the United States, it has been estimated that only about 25% of soldiers remembered to fire their muskets in combat. Many muskets were found with up to 5 charges in the barrel, indicating that soldiers kept reloading without firing. Most of us don’t think clearly in a crisis, we rely on simple well-learned habits that might not be what is needed for the situation at hand. A more expert marksman who doesn’t fire their weapon isn’t performing proportionately to their skill. Clearly, extreme arousal can degrade our performance as Yerkes-Dodson predicts.
What’s harder to tell from this picture is what is different about the soldiers who did fire their muskets. Were those the more expert soldiers in some sense? Or were they the more brave? Or were they different in some other way? In other words, does extreme arousal really degrade performance in general and negate differences in skill, or does it actually bring out differences in skill in greater relief, while demonstrating the importance of a different kind of skills, those less vulnerable to degradation?
A dilemma arises with the Yerkes-Dodson curve if we assume that skills break down under pressure. The skills that are preserved under high arousal seem to be the ones that we have overlearned through long practice. Yet these kind of overlearned skills are also among the hallmarks of the expert. So it isn’t obvious that expert performance should necessarily degrade under high arousal, at least not more than less expert skills. Just because experts rely on more finely honed skills doesn’t mean they should be more subject to losing those skills under stress, they may actually be less vulnerable. How do we resolve this dilemma?
Dissecting the Inverted-U: What are the Real Effects?
One possibly relevant finding is that intellectually demanding tasks seem to be more degraded by arousal and that tasks requiring persistence are less degraded. The Easterbrook Cue-Utilization theory says that this is in part because an increase in arousal leads to a decrease in number of cues that can be utilized, an effect that has been reinforced by other research and has been called perceptual narrowing.
The significance of perceptual narrowing is that it does not seem to be affected by skill level and so it may represent a way of distinguishing the more specific effect of arousal on expert performance. Experts seem to experience this kind of narrowing of the spotlight of their attention under high arousal the same as others do. The question is how it affects their performance.
The most robust effect of high arousal is that our ability to deal with surprises is significantly compromised. High arousal focuses our attention such that we are only aware of a narrow range of predictable central events and we tend to completely ignore unlikely events that would normally get some of our attention. Think about it, this could be good or bad, depending on the role of surprises in the environment. Being unable to respond effectively to a soldier sneaking up on you would be a bad thing in combat. Failing to be distracted by things that don’t affect you would be a positive result.
If my expertise depends on being able to scan the environment widely and respond to novelty, then it seems it will probably be significantly compromised by high arousal. If my expertise depends on being able to focus on a narrow range of stimuli and execute well-learned skills in response to them for an extended period, then high arousal will probably enhance my performance.
Interestingly, the effects of low arousal seem roughly consistent with this model as well. Rather than being blind to things happening at the periphery, at low arousal we seem to be overly distracted by things happening outside the center of our attention, for our attention to wander.
Another effect of high arousal is one seen especially when we feel we are in danger. We tend to not only narrow the spotlight of our attention, but also to rely more on immediate subjective experience and to reject other sources of information that we might ordinarily consider more objective. Under high arousal and threat we tend to resort to our own immediate sensory experience and mistrust all other sources. Again, this seems fairly robust and happens to experts as much as non-experts. Various military programs discovered this effect to their dismay when highly trained personnel have often abandoned their elaborate electronic information systems under combat conditions to depend on their own senses.
One more robust effect of high arousal is variability in some kinds of performance, a phenomenon originally called “blocking” when it was discovered. “Blocking” refers to the appearance of occasional “blocks” where information processing for the task at hand is apparently momentarily interrupted, and decision responses are markedly slower during extended cognitive work. Since this only happens after extended work, it has been interpreted as a kind of “mental fatigue.” Some theorists have interpreted this as an indication that our attention is involuntarily shifting to sources irrelevant to the task at hand.
Beyond the Inverted-U: The Role of Interpretation
One way to make sense of varying performance under high arousal is to take our interpretation of the situation into account. Previous research supporting the Yerkes-Dodson law dealt with situations where the range of interpretations was probably relatively narrow. This leaves margin for us to hypothesize that our interpretation of the situation might play an additional role, even one that challenges the very shape of the Yerkes-Dodson curve.
Some recent theorists have indeed suggested that the Yerkes-Dodson curve only applies under certain conditions and that high arousal consistently improves our performance under other conditions, particularly those where we interpret the situation as an exciting challenge rather than a threat and where we perceive that we have the skills to thrive in it.
This potentially changes the relationship between expertise, arousal, and performance in a fundamental way.
According to these theories of positive psychology, depending on the degree of challenge we perceive and our skills for the situation, a high arousal situation can either facilitate or degrade our performance. We might experience the same situation and the same arousal level negatively as anxiety or anger on the one hand or positively as challenge and excitement on the other hand. This would determine whether the high arousal makes us perform worse or better.
For example, a more or less neutral interpretation might have an effect on performance resembling the Yerkes-Dodson law. A very negative interpretation of the situation might have a catastrophic effect on performance even worse than the Yerkes-Dodson law predicts. A very positive interpretation of the situation would have a more uniformly positive relationship of arousal and performance. In this way, the positive psychology theory of arousal and performance is thought by its proponents to explain a wide range of results.
Conclusion: Arousal and Expertise
Is arousal a serious challenge to the power of expertise?
From research consistent with Yerkes-Dodson we know that …
Low arousal can degrade performance because of our body is inadequately prepared for rigorous demands:
■Insufficient oxygenation of working muscles,
■Cooling is not functioning optimally,
■Digestion and excretion are using energy,
■Available glucose in the liver hasn’t been released,
■Alertness and readiness to respond quickly are compromised.
High arousal can degrade performance because our body is prepared for rapid, strenuous response but not for finely controlled motor skills, reasoning, strategic planning, or flexible response to changes in the situation:
■Excess muscle tension for fine control
■Some fine coordination impaired
■Spontaneous attention shifts prevented
■Intermittent blocking of verbal behavior and decision making with extended effort due to “mental fatigue”
The data we’ve examined so far imply that arousal can very well negate the value of expertise under some conditions. If we’re doing surgery in a combat zone we might well have our skills compromised and a good corpsman with adequate basic skills might be as valuable as or more so than a master surgeon under those conditions. A weaker chess player might well consistently defeat much stronger players in high pressure speed matches if they have less of a tendency to “choke” under the pressure. Objective reasoning and strategic planning are significantly compromised by high arousal, especially if the arousal is negative. Extended performance of some kinds is hampered by “mental fatigue.” In even the best cases, high arousal reduces our ability to respond spontaneously and adaptively to surprises at the periphery of our activity.
This is far from a completely negative assessment of the effect of arousal on expert performance however. Experts can learn to interpret a wider range of situations as positive, possibly preventing the downside of the Yerkes-Dodson curve, can learn to rely on skills that do not require the kind of fine coordination that degrades with high arousal, can learn skills and habits that don’t require planning and reasoning, and can learn skills for managing their own arousal level. In short, in addition to their domain expertise, experts can learn to:
1.Make better use of high arousal
2.Rely on skills that don’t degrade with high arousal
3.Better manage their own arousal level
With this flexibility, arousal is a far less serious challenge to the power of expertise than it might seem from a simplistic application of the Yerkes-Dodson law.
 (Yerkes & Dodson, 1908)
 For example, see (Hockey, 1986) for a review of the evidence for general degradation of performance under high arousal conditions.
 (Easterbrook , 1959)
 (Broadbent, 1971), (Kahneman, 1973)
 “This is usually thought of as a reduction in the ability to deal effectively with relatively unlikely peripheral events in favor of focusing on more likely central events.” (Schmidt, 1989)
 (MacMillan, Entin, & Serfaty, 1994)
 I suppose Obi Wan Kenobi would approve since he recommended this to Luke Skywalker when he attacked the Death Star in Star Wars. Fortunately, Luke’s narrowly defined and well learned task was well suited to performance under high arousal. However in a situation where it is imperative to gather and process information more widely rather than focus on a narrow target, trusting our own senses rather than an information panel could easily become a fatal mistake.
 (Bills, 1931)
 (Bertelson & Joffe, 1963)
 (Broadbent, 1958)
 For example, see: (Csikszentmihalyi, 1998)