What is optimal arousal theory?

Introduction

Optimal arousal theory is a “push” or internal motivation theory. Arousal, like drive, is thought to energize and direct behavior. Arousal theory enjoys some advantages over drive theory, however; it is able to explain behavior that continues at the same level and intensity or increases, and it is not a hypothetical construct but a measurable phenomenon. A construct can be defined as a formal concept representing the relationships between variables such as motivation and behavior. The latter fact permits empirical testing.

Arousal is both physiological and behavioral in its makeup. The physiological component is generally objective and measurable; the psychological component is subjective and observable. The central nervous system controls physiological arousal. The brain stem, for example—particularly the reticular activating system (RAS)—controls levels of consciousness from coma or deep sleep to complete wakefulness, while the cerebral cortex (the outer layer of the brain that controls complex voluntary functions such as thinking, reasoning, motor coordination, memory, and language), in coordination with the RAS and by way of the autonomic nervous system and the endocrine system, provides for moment-to-moment, “gut-level” differences in levels of arousal. According to various theorists, moment-to-moment differences in arousal relate to the type, intensity, quality, and effectiveness of individual behavior, including stable aspects of behavior that make up a significant part of individual personality.

The individual’s arousal level at any given moment is a function of stimulation (in the near past and the present), the individual’s baseline (resting) level of arousal, and his or her stimulus sensitivity. A stimulus is whatever impinges on and is processed by any of the senses (for example, the warmth of a campfire on one’s skin or the sound of a car horn in one’s ears). The effects of stimulation are generally cumulative, persist over time, and have a direct effect on behavior.

Theoretical Perspectives

The Yerkes-Dodson law
provides a starting point for understanding the arousal-behavior relationship. According to that early twentieth century law, there is an inverted-U relationship between motivation and performance; that is, as motivation increases, performance improves up to some point at which performance is maximized. Thereafter, increases in motivation lead to decreases in performance. Thus, the peak of the inverted U is analogous to the point of diminishing marginal returns.

Since arousal is a motivational concept, it is a simple matter to replace the motivation of the Yerkes-Dodson law with arousal, a substitution that was formalized by Donald O. Hebb in 1955. D. E. Berlyne developed this relationship further when he proposed that each individual has an optimal level of arousal (OLA) at which he or she typically feels and performs best and that each individual engages in activities that are calculated to maintain the OLA in a homeostatic (referring to the maintenance of balance or equilibrium in bodily processes) manner.

Arousal both prompts and is the consequence of behavior; for example, a person who is experiencing a low level of arousal is motivated to engage in behavior that has a high stimulus value—that will result in increased overall arousal approaching the optimum. People with chronically low resting levels of arousal will tend to be able to tolerate noise, crowds, excitement, and the like. An individual with a chronically high resting level of arousal, however, will tend to engage in behavior of modest to low stimulus value to avoid exceeding or deviating from his or her OLA. Such individuals tend to engage in more solitary pastimes, avoid noise, avoid crowds, and shun sensation-seeking behavior. According to Hans Eysenck, these differences in behavior, which are attributable to differing resting levels of arousal—particularly cortical arousal—are the hypothetical basis for the dimension of personality called extroversion.

Role of Time and Circumstances

An individual is, however, more than a simple product of his or her mean resting arousal level. Time and circumstances can cause any individual at any given moment to be above or below the OLA and engage in behavior that is either typical or atypical. An extrovert, for example, might feel overwhelmed or become too busy and consequently seek a period of atypical peace and solitude. In addition, while some theorists have posited a single OLA for all behavior, others espouse the idea that there is a separate OLA for each possible behavior, including tasks or problems with different degrees of difficulty. Certain latter-day theorists have noted cogently that the extremes of arousal have both positive and negative hedonic values; that is, low arousal corresponds to boredom or relaxation depending on the situation, and high arousal similarly corresponds to either anxiety or excitement.

Arousal is, in summary, a ubiquitous, continuous, and persistent aspect of human life. It has the theoretical potential to affect—to a greater or lesser extent—virtually all behavior. Practical interests in the arousal-behavior link cover a variety of topics, including the role of arousal in performance, decision making, moods and emotions, and personality formation.

Effect on Task Performance

Arousal affects performance in several ways: It affects how well one is able to complete difficult tasks, perform in the presence of others, and make effective decisions. In the first case, research has generally supported the idea that people perform difficult tasks best at moderate levels of arousal (at the peak of the inverted U), although it is possible to perform easy or moderately difficult tasks effectively over a wider range of arousal. For example, when taking an important examination, one will likely be able to answer easy test questions correctly even if one is very tired, relaxed, or anxious, whereas one will probably find more complex test items difficult to answer if one is only moderately tired or anxious. As a matter of fact, challenging questions often induce the very arousal that interferes with answering them expeditiously and correctly.

The mere presence of others seems to add another measure of difficulty to task performance. Since 1898, social psychologists have studied a phenomenon known as social facilitation. Social facilitation is the tendency of people to perform easy or well-learned tasks more effectively and difficult or poorly learned tasks less effectively in the presence of one or more other persons. Robert B. Zajonc has posited that the mere presence of others (whether they pay attention to the performer or not) is stimulating, hence arousing, and that it is this increase in arousal that causes social facilitation effects. Thus, the presence of others might facilitate the performance of a runner but impair the performance of someone attempting to solve a complex crossword puzzle or pass a difficult exam.

Arousal and Decision-Making Research

Because life is full of pressure-filled and arousing moments and because there is always a demand for people who can remain coolheaded and effective under stressful conditions, researchers have been very interested in the relationship between arousal and decision making. In 1959, J. A. Easterbrook observed that increasing arousal leads to an increasing restriction of cues (stimuli/information), perhaps as a result of a narrowing of attention to essential information. Continued increases in arousal may, however, begin to narrow attention too much and thus interfere with the proper consideration of essential information. Thus, according to the combined results of several researchers, increased arousal actually facilitates the decision-making process up to a point by focusing attention on relevant information and eliminating distraction caused by extraneous detail. Increases in arousal beyond that point begin to screen out crucial information and impair decision making. Again, the Yerkes-Dodson law applies. From a practical standpoint, it seems that practice and training best enable an individual to counteract the effects of increased arousal on decision making.

Relationship to Emotion

Though emotion theorists and scholars differ regarding the precise process of human emotion, they hold at least one belief in common: Autonomic nervous system arousal is central to the experience of emotion. Autonomic arousal provides the subjective physical coloring of the experience of emotion. Therefore, even the novice should not be surprised that there is an interplay between emotion and other arousal-related phenomena. For example, Dolf Zillmann noted that people who had been riding bicycles for exercise and who were angered after they ceased exercising displayed an anger that was considerably greater than might otherwise have been expected considering the circumstances. Physical exercise activates the sympathetic nervous system. After one finishes exercising, the sympathetic nervous system returns to its normal level of activation at a measured pace; thus, for some time after the completion of exercise, one is in a state of decreasing neural arousal. If one is angered during this period, the neural arousal “piggybacks” the arousal generated as the result of becoming angry, causing the anger to be inappropriately intense. This piggybacking of residual neural arousal on subsequently induced emotional arousal, which Zillmann calls the excitation-transfer process, provides a plausible explanation for the human tendency to overemote occasionally about trifling matters or events.

Individuals manifest stable differences in mean arousal level as a function of their typical arousal levels’ proximity to their OLAs. People who are chronically overaroused have only a modicum of room for increased arousal before they exceed their optimal level, while those who are chronically underaroused seem to engage almost constantly in stimulus-seeking behavior. It is reasonable to posit that enduring differences in mean arousal levels lead to more or less stable patterns of behavior that are predictable and intended to optimize arousal. Thus, individual differences in baseline arousal and sensitivity to further arousal may lead to personality formation in the way that Eysenck suggests.

Eysenck has hypothesized that extroversion is composed of two first-order factors: sociability and impulsivity. Extroversion, sociability, and impulsivity are supposed to relate to arousal negatively and linearly, which suggests, for example, that the less aroused a person typically is, the more sociable and impulsive he or she will be; the more aroused someone is, the less sociable and more controlled he or she will be. Eysenck’s theory has inspired considerable research that has yielded illuminating and theory-consistent results. In addition to a large body of research that, when synthesized, finds substantial support for the predicted relationships between various indices of physiological arousal and extroversion, other experimental studies provide theory-consistent results such as the ability of extroverts to tolerate significantly higher levels of noise and pain than introverts and the ability of introverts to detect audio or video signals at a significantly lower intensity threshold than extroverts (an indication of greater stimulus sensitivity). Such findings have useful applications in determining individual occupational and situational suitability.

Newer Research

Though the inverted U of the Yerkes-Dodson law was an early twentieth century conceptualization, it was not until the 1950s that arousal theory emerged to adopt the inverted U. Following the 1949 discovery of the reticular formation’s “arousing” function, a number of arousal theories of motivation, including Hebb’s, were developed. All these theories incorporated the idea that the human being could be underaroused or overaroused. The reticular activating system, in conjunction with the cerebral cortex, was viewed as the homeostatic mechanism for maintaining a balance—or optimal level—of arousal. As a result, optimal arousal theory had a describable and measurable theoretical basis.

The early arousal theories touted a simplified notion of the relationship between indices of arousal and human behavior. There was a tendency to believe that virtually any of a variety of measures of physiological arousal would correlate well with behavioral measures of arousal as well as with one another. The results of research sometimes confirmed and sometimes contradicted this simplistic approach. Behavioral-level measures of arousal were not always well conceptualized: The central nervous system clearly did not act in simple unison with arousal. The results of research varied with the particular choice of cortical or autonomic arousal measure. Using heart rate as a measure, for example, has generally resulted in equivocal results in the study of the relationship between extroversion and arousal. This probably does not mean that the theory is invalid. The heart rate apparently has no simple relationship with cortical arousal. In addition, problems were caused by the design of the behavior measures, the types of experimental activity in which the subjects were engaged, the time of day, and the simplified notion that too much and too little arousal take on only negative hedonic (associated with the seeking of pleasure and the avoidance of pain) significance.

The results of research through the early 1970s suggested that arousal theory had validity but contradicted the simple theoretical connection between behavior and physiology that had been postulated. Such research has led to the modification of some theories and the formation of others. Eysenck, for example, shifted his theoretical focus from chronic or resting levels of arousal underlying extroversion to differences in underlying arousal potential (for example, stimulus sensitivity). Michael J. Apter, on the other hand, offered a new theoretical formation that accounts for the dual hedonic nature of high and low arousal. Apter posited two biological arousal systems, the telic and paratelic, which are roughly equivalent to introversion and extroversion and which underlie the dual metamotivational states. The future of optimal arousal theory seems to lie with the further development of theories that account for the ambiguities of past research, the apparent complexities of biological arousal systems, and the revision of behavioral-level arousal measures to fit the data that have been gathered.

Bibliography

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