What does it take to get you to do something? Motivation? Interest? These are forms of arousal. Robert Mearns Yerkes (1876–1956) and John Dillingham Dodson (1879–1955) discovered there is an empirical relationship between arousal and performance.
Yerkes & Dodson
Robert Yerkes and John Dodson studied rats. The goal was to teach the rats to run through a maze. Dead ends included an electric shock. The results of the study showed if the shock was too low, the rats did not learn as quickly. On the other hand, if the shock was too high, they would forget safe zones they had already learned or retreat and refuse to run the maze at all.
Their article in the 1908 Journal of Comparative Neurology and Psychology was called Relation of Strength of Stimulus to Rapidity of Habit-Formation¹. Although the article did not state the law specifically, the curve represents arousal and not stress.
The single line represents easy tasks. Simple tasks do not have much room for error, and high arousal does not diminish performance of them.
Flashbulb memories are those created during highly emotional or high stress situations. For example, one remembers where one was and what one was doing at the time of assassinations, deaths and tragedies.
Fear conditioning is when we predict adverse results, events and consequences. One needs only to put one’s hand in the fire once to know not to repeat it.
The curve represents more complex situations. When arousal increases beyond a certain level, elements of the task are overlooked or solutions are less well-thought-out with less than desirable long term effects.
When arousal (interest and attention) are low, we are less likely to pay attention to details. Driving is a good example. When we are listening to the radio or talking on our cell phones, we are less likely to notice things like slight differences in engine performance, which can lead to expensive repairs or crashes.
We get comfortable doing tasks and do not devote the appropriate attention to them because they do not arouse us.
When tasks have an appropriate level of arousal, we perform better. With a combination of factors, we are better focused. If the task is new, interesting and/or slightly unpredictable, we devote the appropriate amount of attention to produce the best results.
This is the optimum level of arousal.
We run between ideas without dedicating adequate contemplation when we are over-aroused. We ignore basic details we would have noticed if we were not over-aroused. Typical examples of high-arousal conditions are exhaustion, previous failure and lack of concentration (distraction).
High arousal decreases the quality of performance.
Yagers at Ten Paces
After nearly fifty years of being largely ignored, studies on the Yerkes-Dodson Law took it in a new direction. Bones of contention surfaced in the 1950s.
Arousal ≠ Stress
Yerkes and Dodson both studied the YDL independently after 1908, coming to conclusions which supported the law in practical settings. Both agreed arousal and stress were different things. Where arousal was supported by motivation, interest, curiosity, emotion and satisfaction, stress was created when the actual arousal level did not match the preferred level.²
Studies in the fifties used more stressors than motivators and all ended with only the curvilinear result. While it proved increased stress produced poorer performance, it was a misquote of the Yerkes-Dodson Law.
How difficult a task is bears on the arousal and stress rates. Fifties’ studies did not include simple tasks and did not produce the linear results Yerkes and Dodson got. The most accepted studies were those of Donald Hebb, who studied primates.
Based on the difficulty he encountered teaching the primates (mostly chimpanzees) anything, he disregarded the Yerkes-Dodson linear result and made the curve the only result from the study. Hebb’s curve is still featured prominently, most times to the exclusion of the Yerkes-Dodson graphs, in psychology textbooks as the Yerkes-Dodson Law.
If Hebb’s theory is to be believed, flashbulb memories cannot exist. The highly emotional state required for flashbulb memories would disintegrate the neural pathways which produce memories.
Post-Traumatic Stress Disorder is the penultimate example of the Yerkes-Dodson Law. The high-stress associated with the precipitating event produces long-lasting emotional response and memories. This belies the simple curve as being the only solution to the arousal-performance correlation.
One of the largest variables is the personal level of arousal-tolerance a person brings to the experiment. Some people thrive under higher stress levels and through distraction. Others simply cannot compensate for outside influences or emotionally-charged situations.
The Yerkes-Dodson Law is one of the most quoted in all of neuroscience and behavioral science, yet it is probably the least read. Only when the law was nearing its 100th anniversary have researchers begun to delve into the complexities of the Yerkes-Dodson Law with reference to job performance.
Hanoch and Vitouch argued the accepted and over-simplified version of the YDL needs to be reestablished using new research presented between 1977 and 2007. The argument is “what Yerkes and Dodson had in mind was more sophistication than what their U-entranced successors made of it … later generations let the law collapse into one single curve with its idealized and highly abstract, quasiunidimensional axes”.³
While it is easier to just accept the oversimplified version of the YDL in terms of coping with work and familial situations, there is much to discover in the ways the body responds to hormones and emotions in terms of memory and critical thinking (problem-solving) with the expanded, original version of the Yerkes-Dodson Law.
1 YERKES, R.M. & DODSON, J.D. (1908). The Relation of Strength of Stimulus to Rapidity of Habit-Formation. Journal of Comparative and Neurological Psychology. Volume 18. pp.459-482
2 STOKES, Alan. & KITE, Kirsten. (1994). Flight Stress: Stress, Fatigue, and Performance in Aviation. U.K: Ashgate. pp. 31-45
3 HANOCH Y, VITOUCH O. (2004) When less is more: information, emotional arousal and the ecological reframing of the Yerkes-Dodson law. Theory & Psychology. 14(4): pp. 427–452.
Do you have any flashbulb memories? How does your arousal rate change your performance? Have you seen the Yerkes-Dodson Law in practice where you work?
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© Red Dwyer 2012
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