Many people feel that their performance improves when they feel pressured. For example, you’ve probably been surprised more than once at how easily you’ve managed to memorize a test agenda despite studying it only the day before, compared to other times when you’ve spent much more time.

In this article we will talk about Yerkes-Dodson’s law, as the inverted U model is usually called about the relationship between activation level and performance. This hypothesis was proposed by Robert Yerkes and John Dodson more than a century ago; however, it is still valid today because of the remarkable robustness it has demonstrated.

Yerkes-Dodson’s law or inverted U model

In 1908 the psychologists Robert Mearns Yerkes and John Dillingham Dodson published their inverted U model, the result of their studies on the influence of pressure (which can be understood as the level of stress, activation or physiological and cognitive alertness) on performance in tasks involving complex mental operations.

Yerkes and Dodson’s model suggests that the relationship between stress and performance can be represented as an inverted U-shape. This means that the performance will be optimal if the activation level is moderately high ; on the other hand, if it is too high or too low it will have a negative impact on the outcome of the task.

Thus, Yerkes-Dodson’s law states that the best way to enhance performance is to increase motivation to carry out target tasks, but it is equally important to ensure that the workload does not become unmanageable, as this interferes with the natural development of the activity and generates unpleasant feelings.

When we carry out tasks with a low level of stress or alertness, we often get bored or the lack of pressure reduces our productivity; if the demands are excessive we tend to experience feelings of anxiety and general psychological discomfort. On the contrary, when the task is stimulating and challenging we concentrate more.

In this sense we can relate Yerkes-Dodson’s law to another very popular psychological concept: the state of flow described by Mihály Csíkszentmihályi. According to this author, stimulating tasks, appropriate to the level of ability, with clearly defined objectives and with immediate feedback generate a complete and gratifying mental involvement.

Factors influencing the relationship between stress and performance

There are at least four factors that have a very relevant role in the relationship between the level of activation and productivity : the complexity of the task, the skill level of the person completing it, his personality in general and the anxiety-trait factor in particular. Each of them modulates in a key way the effects of Yerkes-Dodson’s law.

1. Complexity of the task

If the task we have to carry out is difficult, we will need to invest more cognitive resources (relating for example to attention or working memory) than if it were not. Consequently, complex tasks require a lower level of pressure to achieve optimal performance than simple ones, since they are stimulating by themselves.

This suggests that it is important to adapt environmental pressure levels to the difficulty of the task in order to boost productivity, so quiet environments are more suitable for challenging activities, while an enriched environment can help improve quality when tackling easy tasks.

2. Skill level

As with the difficulty of the tasks, taking into account the skill level of the subject is critical in determining what the ideal environmental pressure is. We can say that the practice in a domain reduces the difficulty of the tasks included in it , so relating these two variables can be useful when applying Yerkes-Dodson’s law.

3. Personality

It would be reductionist to think that modifying the level of stimulation or environmental pressure alone can allow us to reliably influence the performance of other people: if we did so, we would be ignoring something as important as the personality of each individual.

Thus, for example, if we follow the neurobiological theory of personality proposed by Hans Eysenck we can deduce that extraverted people tend to need a higher level of brain activation to reach their optimal performance, while biologically introverted people normally prefer that environmental pressure be minimal.

4. Anxiety-trait

The personality factor we know as “trait-anxiety” refers to the tendency to experience negative emotions related to anxiety, such as restlessness, fear, and worry. Trait-anxiety constitutes the core of the construct Neuroticism ; in this sense it is opposed to the factor Emotional stability.

As you might expect, people who have a strong tendency to feel anxiety almost always react negatively to increased stress levels. As with introverted people, it can be a serious mistake to ignore that people with this characteristic work better with low levels of stimulation.