Yerkes-Dodson Law
Overview
Harvard University animal behaviorists, Robert Mearns Yerkes (1876-1956) and John Dillingham Dodson (1879-1955), conducted a series of experiments to try to ascertain if a correlation existed between one’s stress level and performance. The Yerkes-Dodson Law, or inverted-U hypothesis, notes there is an optimal level of arousal which facilitate one’s optimal performance. Further, if one’s stress/anxiety were to fall below or above this level, their performance would deteriorate.[1,2]
Background
After obtaining his undergraduate degree from Ursinus College, Robert Mearns Yerkes earned his doctoral degree at Harvard University in 1902. Following his studies, Yerkes continued on as instructor and then as professor of psychology at Harvard until 1917. His early studies of the behavior of invertebrates progressed to work with small mammals and then to work with humans. In particular, Yerkes was interested in psychological testing of humans and significantly contributed to the development of multiple-choice testing and a widely used point scale for measuring human mental ability in 1915. Continuing, during World War I, he spearheaded the first mass-scale testing program, which administered nearly two million psychological tests.[3]
In 1924, Robert Mearns Yerkes became professor of psychology at Yale University. Renewing his studies of chimpanzees and other higher primates, he became the world’s foremost authority on the great apes. His major work, The Great Apes (1929; cowritten with his wife, Ada Watterson Yerkes), was considered the standard work on the psychology and physiology of great apes for several decades. Following, in 1929, Yerkes established the Yale Laboratories of Primate Biology in Orange Park, Florida, to study the neural and physiological bases of behavior. This locale was renamed Yerkes Laboratories of Primate Biology after Yerkes resigned as director in 1941. Continuing to teach, he retired from his teaching position at Yale in 1944.[4]
Less is known about Yerkes’ counterpart, John Dillingham Dodson, who sought out a more private life. Obtaining a master's degree from Harvard University, Dodson followed with earning his doctorate in psychology from the University of Minnesota. Much of his academic career was at the Bowling Green College of Commerce, which later became part of Western Kentucky University.[5]
Description
In 1908, Robert Mearns Yerkes and John Dillingham Dodson conducted a series of behavior-modification experiments to examine the relationship between arousal level and quality of performance. By examining the speed with which Japanese dancing mice learned to discriminate between two different boxes in relation to the levels of electric shock they received upon choosing the incorrect one, Yerkes and Dodson sought to determine if there was an ideal level of stress requisite for optimal performance.[6]
Their findings, dubbed the Yerkes-Dodson Law (also known as the inverted-U hypothesis) indicates there is an optimal level of arousal (e.g., motivation or anxiety) for tasks where moderate levels of arousal facilitate one’s problem-solving abilities.[7] Despite the myriad of research noting the ill-effects of stress, Yerkes and Dodson’s research suggests that a requisite level of stress benefits performance.[8] However, if one’s stress/anxiety is too high (and conversely, too low) their optimal learning and performance fail to occur. Yerkes and Dodson’s research indicated that increased drive improves one’s performance to a point; beyond-which, a deterioration of performance occurs.[9]
[10]
As demonstrated in the graph above, the shape of the curve varies based on both the complexity and familiarity of a particular task. Those deemed difficult or are unfamiliar require lower levels of arousal to facilitate concentration. Conversely, tasks demanding stamina and/or persistence require increased levels of arousal, inducing and increasing one’s motivation.[11]
In 1983, Sheldon Cohen, Tom Kamarck, and Robin Mermelstein developed the Perceived Stress Scale.[12] The most widely-used measure of global perceived stress, the PSS has been translated into several languages and utilized as a robust predictor of health and disease.[13]
Employing the PSS, higher scores correspond to higher levels of stress, with average levels indicative of the optimal level of arousal and subsequent performance. As stress levels increase above the level of optimized arousal or below such level, the increased or lack-there-of sense of stress lead to a detrimental effect on productivity. For example, if there was a limited level of arousal, one might not feel motivated or inclined to complete a task. Conversely, if one experienced heightened levels of stress that were unbearable, they would likely find it more difficult to concentrate on the task at hand, particularly for a sustained period of time.[14]
In 2016, Harvard Business Review published the following data, based on a national study replicated by Sheldon Cohen and Denise Janicki-Deverts, of Carnegie Mellon University, across 1983, 2006 and 2009:[15,16]
Cohen and Janicki-Deverts found that across all 3 surveys, stress was higher among women than men; with a negative correlation across age, education, and income. Unemployed persons reported high levels of stress, while the retired reported low levels. Further, they found all associations were independent of one another and of race/ethnicity. Additionally, while minorities generally reported greater stress than White persons, the differences lost significance when adjusted for other demographics.[17]
Discussion
Since their pioneering work over a century ago, Yerkes and Dodson's findings have been replicated in numerous studies utilizing modern techniques and statistical analyses,[18-20] widely applied to performance in many contexts including athletic training,[21] workplace conditions,[22,23] as well as video games.[24]
In a paper published in 2015, Chaby et al. found that adult rats exposed to chronic stress during adolescence increase their foraging performance in high-threat conditions by 43%, compared to rats raised without stress. They note these findings suggest that stress during adolescence seem to prepare rats to better function under future threat, supporting hypotheses that describe an adaptive role for the long-term consequences of early stress. Such hypotheses (e.g., the thrifty phenotype and maternal mismatch hypotheses) often predict that early stress will impair one’s performance in low-threat conditions later in life. However, Chaby et al. did not find any difference in performance under low-threat conditions between adolescent-stressed and unstressed adult animals.[25]
To understand why stress during adolescence may affect performance in high-threat but not in low-threat conditions, the team explained their findings in the framework of the Yerkes-Dodson Law. Chaby et al. tested rats in a moderately challenging, problem-solving foraging task that required varying motor actions and object manipulations under both high-threat conditions (e.g., auditory and visual predator cues, bright light) and low-threat conditions (e.g., standard laboratory conditions, dim red light). Under high-threat conditions they found the control (unstressed animals) decreased their performance by an average of 28% ± SE 9% (number of rewards obtained) compared to their performance in a prior low-threat test ([final-initial/initial] × 100). Remarkably, they noted that high-threat conditions did not detract from the performance of rats that had experienced adolescent-stress, with adolescent-stressed rats showing a small increase in performance (2% ± SE 16%) compared to their performance in the prior low-threat test. The team deduced the effect of adolescent-stress on the relationship between performance and threat condition could be underpinned by a shift in the curvilinear relationship between performance and arousal, as described by the Yerkes-Dodson Law. Within this framework, exposure to adolescent-stress would cause an increase in optimal arousal range, but adolescent-stressed animals would still continue to show a decline in their performance after stress/arousal exceeds their optimal level.[26]
While the Yerkes-Dodson Law seems reasonable and useful, it has received mixed support from psychologists for a myriad of reasons.[27]
In 2015, Corbett published an article in the Journal of Managerial Psychology, in which the Yerkes-Dodson Law was widely criticized. Corbett noted that in recent years, a number of researchers have argued that the increase in work stress levels is, “an imminent, if not already evident costly disaster.”[28] One such example occurred in 2002; the European Commission estimated that the yearly cost of work-related stress in Europe was 20,000 million per year.[29] Corbett continued to note that countless research articles on work stress have been published in academic journals, painting a highly complex picture of the antecedents, causes, and consequences of work-related stress,[30] with many articles offering clear evidence-based guidance on how stress might best be reduced and managed. However, when one looks inside many of the best-selling management and organizational behavior/psychology textbooks, there is one theoretical model of stress – the Yerkes-Dodson Law (YDL).[31]
A 1911 replication of Yerkes’ and Dodson’s study using baby chickens revealed a consistent positive linear relationship between the two variables regardless of task difficulty.[32] A replicative study in 1915 using kittens revealed a positive linear relationship for “easy” and “medium difficulty” tasks and a negative linear relationship when the kittens undertook a “difficult” discriminatory task under very poor lighting conditions.[33] Results from these studies offer a somewhat confusing representation of the data whereby height on the x-axis denotes slower rates of learning. Corbett adds that these studies also fail to offer a coherent picture of how task difficulty, stimulus strength, and learning are interrelated. Moreover, the only consistent finding is that the learning of simple tasks is facilitated by increasing levels of punishment for failure.[34]
In the 1960s, with the decline in animal experimentation, the YDL received minimal attention in psychology journals.[35] There were, however, articles published that expressed concern about the validity of Yerkes and Dodson’s methodology, theory, and findings.[36] Despite these criticisms, Corbett notes that by the 1970s, the YDL was firmly established as a psychological “law for all seasons.”[37] Perhaps the most notable supporter of the YDL endocrinologist Hans Selye, who published over 1,500 papers and 30 books on stress, noting his strongly reinforced belief in the validity of the inverted-U curve. In 2003, Muse et al., noted the modern-day variant of the YDL now declared that “some stress is necessary for optimal performance and stress levels below or above this optimal level are detrimental to performance.”[38]
Calls against the use of YDL have been outspoken by some. In 1965, Brown called for the YDL to be “repealed”[39] while in 1988, Neiss noted it should be “retired.”[40] Muse et al. (2003) conducted an analysis of peer-reviewed psychology journal research papers on stress and work performance published between 1975 and 2000 and found only two papers (4% of the sample) offering any support for the inverted-U curve. On the contrary, they found that nearly half of the reviewed papers supported a “negative linear” hypothesis, suggesting that “stress at any level consumes an individual’s time, energy, and attention, taking away from the task at hand and consequently inhibiting performance.”[41] In this regard, stress is detrimental to one’s performance, with increasing levels of stress becoming increasingly detrimental.
Corbett notes that if the negative linear hypothesis is correct, one would expect to see evidence of a positive correlation between performance and lower levels, or absence, of stress. However, such evidence is hard to find because there has been a scarcity of data to analyze in this regard. Muse et al. (2003) discovered the majority of researchers studying stress failed to make any distinction between conditions of “under-stress” and “over-stress,” with both classified as dysfunctional deviations from the supposedly optimal condition of moderate stress. Further, Corbett notes that standard stress measures such as the Job-Related Tension Index [42,43] as well as the role conflict and role ambiguity scales [44] actually exclude any explicit questions to evaluate stress resulting from work under-load, boredom, or lack of stimulation, preventing the capture of data on the left-half of the inverted-U.[45,46]
Perhaps the most surprising feature of the YDL, according to Corbett, is the way in which inconsistent findings from laboratory experiments on small mammals have been “extrapolated to almost every facet of human task performance;” from product development teamwork [47] to the piloting of aircraft, [48], competing in sport [49] and solving complex cognitive puzzles.[50] Corbett continued that the over-generalizations and ambiguities of interpretation not only sustain the folk model status of the YDL, but maintain its ubiquitous presence in organizational psychology and management textbooks.[51]
Based on his ethnographic study, Latour (1990) suggested that when scientists are presented with a well-constructed graph showing data with which they disagree, they tend to feel under pressure to either muster their own counter-evidence in the form of even better graphs or to accept the consensus view.[52] Muse et al. (2003) ended their critical analysis of the YDL not by proposing the abandonment of the inverted-U curve, but by suggesting theoretical and methodological “improvements to finally give the inverted-U theory a fair test.”[53] In 2002, Teigen pointed out: “when observations appear to be in disagreement with a law of nature, we tend to doubt the truth of the observations rather than the truth of the law”.[54]
Corbett continues that the YDL is problematic in many regards due to many organizational psychology and management textbooks making reference to some theories of behavior for which there is little if any empirical support, such as Maslow’s hierarchy of needs. The introductory nature of these texts tend to simplify the nuances and complexities of organizational research, yet they tend to introduce the YDL as a “scientific law of behavior” with little or no critical commentary. With the YDL claiming that, to a point, higher levels of stress can lead to higher levels of performance, this principle has found a welcome home in management textbooks as it reflects and reproduces certain managerial values and assumptions under the guise of objective science.[55] Brief (2000) noted that the YDL has been used by management to monitor and control employee performance.[56] In practice, therefore, management often “attempts to maintain stress at optimal levels for performance rather than endeavoring to minimize stress. Moreover, it places responsibility on the managers for keeping the amount of stress on employees at an optimal level.”[57] However, such practice runs the risk of increasing stress to unacceptable levels.[58]
Corbett notes it is surely expecting too much of managers to understand and manage every employee’s optimal level of stress, especially as they are often under stress themselves.[59] Yet Sosik and Godshalk (2000) point out the logic of the YDL requires precisely this ability despite counter-evidence from psychology research, which show that supportive management can significantly reduce stress at work and improve performance.[60]
A 2016 article by Harvard Business Review refers to the Perceived Stress Scale, noting if one’s score approaches or exceeds a level of 20, there are some strategies that may help reduce stress to a more productive level. Such methods include:[61]
Increase your control. One simple solution to lowering stress is to find more ways to increase your control over the work you do. People tend to believe that high-level positions bring a lot of stress, but research suggests just the opposite: Leaders with higher levels of responsibility experience lower stress levels than those with less on their shoulders. This is because leaders have more control over their activities. Independent of where you sit in the organizational hierarchy, you may have ways to increase your sense of control—namely, by focusing on aspects of your work where you can make choices (for example, choosing one project over another or simply choosing the order in which you answer e-mails).
Find more opportunities to be authentic. Evidence suggests that people often experience feelings of inauthenticity at work. That is, they conform to the opinions of colleagues rather than voicing their own, and they go with others’ flow rather than setting their own agenda. This has important implications for your stress level and performance. When people behave in inauthentic ways, they experience higher levels of anxiety than when they are simply themselves. So, try to find ways to express who you are at work, such as offering to share your unique talents or decorating your office to reflect who you are.
Use rituals. Basketball superstar Michael Jordan wore his North Carolina shorts underneath his Chicago Bulls shorts at every game; Curtis Martin of the New York Jets reads Psalm 91 before every game; and Wade Boggs, as third baseman for the Boston Red Sox, ate chicken before each game and took batting practice at exactly 5:17 p.m., fielded exactly 117 ground balls, and ran sprints at precisely 7:17 p.m. These rituals may sound strange, but they can actually improve performance.
In one recent experiment, people asked to hit a golf ball into a hole received either a so-called “lucky” golf ball or an ordinary golf ball. In another experiment, participants performing a motor dexterity task (placing 36 small balls in 36 holes by tilting the plastic cube containing them) were either asked to simply start the game or heard the researcher say they would cross their fingers for them. The superstitious rituals enhanced people’s confidence in their abilities, motivated greater effort — and improved subsequent performance.
Similarly, research in sports psychology demonstrates the performance benefits of pre-performance routines, from improving attention and execution to increasing emotional stability and confidence. And recently, colleagues at HBR have found that when people engage in rituals before undertaking high-stakes tasks, they feel less anxious and stressed about the task and end up performing better as a result.
For over a century, the Yerkes-Dodson Law continues to be one of the foremost models of stress. Due to the controversial debates regarding its applicability and replicability in human models, continued research is likely needed to further solidify its position in the field of psychology.
Contributed by: Jennifer (Ghahari) Smith, Ph.D.
References
1 Corbett, M. (2015). From law to folklore: work stress and the Yerkes-Dodson Law. Journal of Managerial Psychology, 30(6), 741-752.
2 Yerkes Dodson law. (2006). In J. E. Roeckelein (Ed.), Elsevier's dictionary of psychological theories. Elsevier Science & Technology.
3 “Robert M. Yerkes: American Psychologist,” Britannica (accessed 2-1-21) www.britannica.com/biography/Robert-M-Yerkes
4 Ibid.
5 . Brothen, T. (Feb 2012). What ever happened to John Dodson? History of Psychology. 15 (1): 100–05. doi:10.1037/a0024801
6 Corbett, M. (2015)
7 Yerkes Dodson law. (2006)
8 Gino, F. (2016) “Managing yourself: Are you too stressed to be productive? Or not stressed enough?” Harvard Business Review (accessed 2-4-21) hbr.org/2016/04/are-you-too-stressed-to-be-productive-or-not-stressed-enough
9 Yerkes Dodson law. (2006)
10 Gino, F. (2016) Harvard Business Review
11 Ibid.
12 Cohen S, Kamarck T, Mermelstein R. A global measure of perceived stress. Journal Of Health And Social Behavior. 1983;24:385–396. doi:10.2307/2136404.
13 Cohen S, Tyrrell DA, Smith AP. Negative life events, perceived stress, negative affect, and susceptibility to the common cold. Journal of Personality and Social Psychology. 1993;64:131–140. doi:10.1037/0022-3514.64.1.131.
14 Gino, F. (2016) Harvard Business Review
15 Ibid.
16 Cohen, S. and Janicki-Deverts, D. (2012), Who's Stressed? Distributions of Psychological Stress in the United States in Probability Samples from 1983, 2006, and 20091. Journal of Applied Social Psychology, 42: 1320-1334. doi.org/10.1111/j.1559-1816.2012.00900.x
17 Ibid.
18 Telegdy GA, Cohen JS. Cue utilization and drive level in albino rats. Journal of Comparative and Physiological Psychology 1971; 75:248-253; dx.doi.org/10.1037/h0030825
19 Anderson KJ. Impulsitivity, caffeine, and task difficulty: A within-subjects test of the Yerkes-Dodson law. Personality and Individual Differences 1994; 16:813-829; dx.doi.org/10.1016/0191-8869(94)90226-7
20 Dickman SJ. Dimensions of arousal: Wakefulness and vigor. Hum Factors 2002; 44:429-442; PMID:12502160; dx.doi.org/10.1518/0018720024497673
21 Stinson C, Bowman DA. Feasibility of training athletes for high-pressure situations using virtual reality. IEEE Trans Vis Comput Grap 2014; 20:606-615; PMID:24650988; dx.doi.org/10.1109/TVCG.2014.23
22 Chang LC, Mahoney JJ, Raty SR, Ortiz J, Apodaca S, De La Garza R. Neurocognitive effects following an overnight call shift on faculty anesthesiologists. Acta Anaesthesiol Scand 2013; 57:1051-1057; PMID:23593975; dx.doi.org/10.1111/aas.12120
23 Giddings B, Thomas J, Little L. Evaluation of the workplace environment in the UK, and the impact on users' levels of stimulation. Indoor and Built Environment 2013; 1420326X13476078; dx.doi.org/10.1177/1420326X13476078
24 Jeong EJ, Biocca FA. Are there optimal levels of arousal to memory? Effects of arousal, centrality, and familiarity on brand memory in video games. Comput Hum Behav 2012; 28:285-291; dx.doi.org/10.1016/j.chb.2011.09.011
25 Chaby L, Sheriff M, Hirrlinger A & Braithwaite V (2015) Can we understand how developmental stress enhances performance under future threat with the Yerkes-Dodson law?, Communicative & Integrative Biology, 8:3, DOI:10.1080/19420889.2015.1029689
26 Ibid.
27 Yerkes Dodson law. (2006)
28 Corbett, M. (2015)
29 Milczarek, M. , Schneider, E. and González, E.R. ( 2009 ), "Stress at work: facts and figures", European Agency for Safety and Health at Work, Risk Observatory Report No. 9, Office for Official Publications of the European Communities, Luxembourg.
30 Staal, MA. Stress, Cognition, and Human Performance: A Literature Review and Conceptual Framework. 2004, doi:info:doi/.
31 Corbett, M. (2015)
32 Cole, L. W. (1911). The relation of strength of stimulus to rate of learning in the chick. Journal of Animal Behavior, 1(2), 111-124.
33 Dodson, J. D. (1915). The relation of strength of stimulus to rapidity of habit-formation in the kitten. Journal of Animal Behavior, 5(4), 330-336.
34 Corbett, M. (2015)
35 Hancock, P. A. , Ganey, H. C. N. , & Szalma, J. L. (2002, December). Performance under stress: A re-evaluation of a foundational law of psychology. Paper presented at the Army Science Conference, Orlando, FL.
36 Brown, W. P. (1965). The Yerkes-Dodson law repealed. Psychological Reports, 17(2), 663-666.
37 Teigen, K. H. (1994). Yerkes-Dodson: A law for all seasons. Theory & Psychology, 4(4), 525-547.
38 Muse, L. A., Harris, S. G., & Feild, H. S. (2003). Has the inverted-U theory of stress and job performance had a fair test? Human Performance, 16(4), 349-364.
39 Brown, W. P. (1965)
40 Neiss, R. (1988). Reconceptualizing arousal: psychobiological states in motor performance. Psychological Bulletin, 103(3), 345-366.
41 Muse, L. A., Harris, S. G., & Feild, H. S. (2003)
42 Anderson, C. R. (1976). Coping behaviors as intervening mechanisms in the inverted-U stress-performance relationship. The Journal of Applied Psychology, 61(7), 30-34.
43 Kahn, R. L., Wolfe, D. M., Quinn, R. P., Snoek, J. D., & Rosenthal, R. A. (1964). Organizational stress: Studies in role conflict and ambiguity. John Wiley, Oxford.
44 Rizzo, J. R., House, R. J., & Lirtzman, S. I. (1970). Role conflict and ambiguity in complex organizations. Administrative Science Quarterly, 15(2), 150-163.
45 Muse, L. A., Harris, S. G., & Feild, H. S. (2003)
46 Corbett, M. (2015)
47 Chong, D. S. F., van Eerde, W., Rutte, C. G., & Chai, K. H. (2012). Bringing Employees Closer: The Effect of Proximity on Communication When Teams Function under Time Pressure. The Journal of Product Innovation Management, 29(2), 205.
48 Stokes, A. (1994). Flight stress: Stress, fatigue, and performance in aviation (Book).
49 Sonstroem, R. J., & Bernardo, P. (1982). Intraindividual pregame state anxiety and basketball performance: A re-examination of the inverted-–U curve. Journal of Sport Psychology, 4(3), 235-245.
50 de Kloet, ,E.R., Oitzl, M. S., & Joëls, M. (1999). Stress and cognition: are corticosteroids good or bad guys? Trends in Neurosciences, 22(10), 422-426.
51 Corbett, M. (2015)
52 Latour, B.: Drawing things together. In: Lynch, M., Woolgar, S. (eds.) Representation in Scientific Practice, pp. 19–68. MIT Press, Cambridge (1990)
53 Muse, L. A., Harris, S. G., & Feild, H. S. (2003)
54 Teigen, K. H. (1994). Yerkes-Dodson: A law for all seasons. Theory & Psychology, 4(4), 525-547.
55 Corbett, M. (2015)
56 Brief, A. P. (2000). Still servants of power. Journal of Management Inquiry, 9(4), 342-351.
57 Le Fevre, M., Matheny, J., & Kolt, G. S. (2003). Eustress, distress, and interpretation in occupational stress. Journal of Managerial Psychology, 18(7), 726-744.
58 Corbett, M. (2015)
59 Ibid.
60 Sosik, J. J., & Godshalk, V. M. (2000). Leadership styles, mentoring functions received, and job-related stress: A conceptual model and preliminary study. Journal of Organizational Behavior, 21(4), 365-390.
61 Gino, F. (2016) Harvard Business Review