Advantages of a unified science and a unified theory of pain

Reply

Advantages of a Unified Science and a Unified Theory of Pain Peter S. Staats, Hamid Hekmat, * and Arthur W Staatst

e are pleased to have an opportunity to respond to our colleagues. In each case the commentators provided a cogent, effective, and thoughtful analysis of the psychological behaviorism (PB) theory of pain. While we cannot respond to each and every point, we have selected the main concerns and positions and attempt to respond to them in a manner that clarifies the tenets of PB theory of pain.

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THE NEED FOR A COMMON LANGUAGE (RESPONSE TO SULLIVAN) Sullivan astutely raises interesting questions and issues that we can use in elaborating principles of unification. He agrees with PB in that pain involves emotional reactions-that pain is a response to a nociceptive stimulus, a response that involves the same central nervous system mechanisms as negative emotional responses. He agrees that the pain response follows the principles of emotional responding and accordingly should be related to the study of emotions. He also agrees with PB theory in that it is important to integrate the biomedical consideration of pain with the effects of culture and is concerned with how emotion can be included in this integration. His discussion, however, highlights the need for developing one framework theory with one theory language. The separate theories have developed separate theory languages. He uses a cognitive theory language (a social constructionist language) in considering matFrom Johns Hopkins University, Baltimore, MD, the 'University of Wisconsin-Stevens Point, Stevens Point, WI, and the tUniversity of Hawaii, Honolulu, HI. Reprint requests: Peter S. Staats, MD, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins Medical Center, 600 North Wolfe Street, Osler 304, Baltimore, MD 21287-5354.

Pain Forum 5(3): 215-219, 1996

ters related to emotion. One of his major points is that in the social construction view "emotion is an irreducibly sociocultural product." We see here one of the reasons our field needs a unified theory language that includes basic conditioning principles. The individual's emotion as a sociocultural product is the product of learning. That is how culture is transmitted, through learning, as opposed to unlearned responding, which is the result only of biology. What must be realized is that the social constructionist view involves how social experience affects behavior. But social constructionists developed their theory apart from, and to a good extent opposed to, the field that has involved the systematic laboratory study of learning principles. The lack of a bridge here prevents social constructionism in psychology being connected to the relevant basic science. The PB theory of pain agrees with the social constructionist view that emotion is affected by learning (culture). Psychological behaviorism however, takes the position that it is important to construct a theory of pain on the foundation of basic principles. Thus, it develops its basic theory in a hierarchical manner interrelating the principles of classical and operant conditioning. When this is done it is possible to see the relationship of emotion and pain, as well as to consider the social phenomena of interest to social constructionists. It is also possible to clarify theory problems that arise when the theory language used is not so precise. The emotional state can influence pain, and pain can have a reciprocal effect on subsequent emotion. Social constructionist theories such as Wittgenstein's artificially separate emotion from sensation. We feel that the separatistic perspectives do not allow true integration. For example, Sullivan says that a "strong social constructionist view will not work for pain" and follows this by saying "There are strong cross-cultural similarities in pain experience ...." This suggests a problem in considering individual differences in response to pain while

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recognizing similarities in the response to pain by people of particula r cultures. However, there is no disjunction in considering both within the unifying principles of the PB theory. Individual differences (within culture similarities) and cross-cultural differences in pain do not represent disjunctions when analyzed in terms of the same unifying principles . There are -similarities of experience of those raised within a culture , and this results in similarities in learning and hence in response to pain stimuli. And, within a culture , there remain individual differences in experience that produce differences in pain experience and behavior. As one example of cultural difference, there may be different emotional responses to being unable to work. Someone raised in a culture where the "work ethic" (as defined by the child's experience) is very high will learn different emotiona l responses to idleness than someone raised with less stringent experiences. The two individuals will experience different emotional states as a consequence of forced unemployment, and that difference in emotional state will result in different pain responses to a chronic nociceptive stimulus that prevents working. The PB theory can consider in a unified manner individual differences in pain that occur through various types of differences in experience.

ANALYSIS REQUIRES AN ANALYTIC THEORY (RESPONSE TO TAIT) Of the commentators, Tait's position appears to be the most at odds with the PB theory of pain. His difficulty is revealed by his manner of analysis. Rather than considering the theory as a unified whole, he treats one part as involving classical conditioning," another part as "operant conditioning," and still another as "social learning" in nature. Looking for trees he misses the forest. Tait begins the task with an eclectic (divided) approach . His analysis is thus eclectic. Using a variety of concepts such as "expectancy" and "maladaptive coping response," he refers to a variety of research studies (some relevant and some not) and then sketches his own approach, which is that research on pain should restrict itself to "specifying processes relevant to each discrete area" of concern . His final statement reflects his entire approach , "Unification, if it ever occurs , will require more knowledge than we now have." Our theory suggests that pain is a complex multifaceted phenomenon. A comprehensive theory can be expected to have some complex ity as well. Understanding such a theory to the point of being able to use it requires an investment. Without the investment the value of the theory for analyzing phenomena may be missed. Tait criticizes the PB theory's principles for being inconsistent with research findings, but there is

no inconsistency. For example , he considers the finding that self-reported postoperative pain is not predicted by a preoperative anxiety measure to be counter to the PB measure expectations . However, no effect of anxiety would be expected by the PB pain theory if the preoperative test measured anxiety (a negative emotional state) that was elicited by the pending surgery, and that the anxiety was not present postoperative ly at the time the pain was measured. However, if the preoperative test measured a continuing anxiety (negative emotional state) that was functioning at the time the pain report was obtained, PB theory would indeed expect an effect. This is precisely what the study revealed; preoperative anxiety did not correlate with postoperative pain, however, self-reported pain on day 3 was highly correlated (P < .01) with anxiety state at that time. Moreover, a higher anxiety state on day 3 correlated significantly with a longer postoperative stay, as PB pain theory would expect [2]. The point is, the PB theory of pain employs specified concepts and principles and thus serves as the basis for detailed analysis (and research) in a way that vaguer concepts such as expectancies do not. But it is necessary to get into the theory before it can be used analytically. The same is true of the AI-Absi and Rokke [1] study that Tait believes PB theory cannot handle. In that study one group of subjects is told electric shock will be delivered to them when immersing a hand in cold water ; another group is told about the medical dangers of immersing their hand in cold water, with an indication that this danger was "why we asked you about any medical conditions that you might have." The waterimmersion-anxious subjects reported more cold pressor pain than shock-anxious subjects. When a PB analysis is made, we can see that the directions given one group focused on the cold pressor experience, while the directions given the other took their attention away from the cold pressor experience. Moreover, studies of cold pressor pain have shown clearly that distractions that take subjects ' attention away from the cold pressor experience reduce the experience of pain [4,6]. This study fails to demonstrate that increasing anxiety does not increase pain response to a nociceptive stimulus ; just the reverse. As stated by AI-Absi and Rokke, "Much of the literature on the relationship between anxiety and pain has indicated that these constructs are positively correlated" [1]. Humans, in the pain area as elsewhere , confront different arrays of stimuli that evoke different combinations of behavior. If we wish to understand human behavior in an analytic way we must employ a theory capable of making that analysis . These are examples; the other studies that Tait raises are of the same type. He considers the several studies he mentions to be critical of the theory because he

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does not know how to analyze them within the theory and instead employs common-sense concepts, like expectancy, that are vague and poorly defined and not adequate to the task. Tait thus fails to see the value of the theory's treatment of pain and emotion as common phenomena that follow the same conditioning principles. While he considers pain to be a centrally mediated phenomenon, he states "the evidence for emotion as a similar central nervous system is lacking." The fact is, that although many researchers working with emotion employ peripheral measures, there is a solidly based treatment of central nervous system mechanisms involved in emotion. The value of the PB theory of pain with respect to this issue is shown in the words of Sullivan who states that the present author's "hypothesis illustrates how the physiology and psychology of pain might be linked, and has clear clinical implications," and Jensen who states that the present authors "open a needed discussion concerning pain and emotion:' The pain-emotion link is a crucial one in unifying biological and behavioral study. The value of that link for clinical work and basic science is such that the hypothesis calls for extensive research. Tait does not realize that this is an example of the heuristic value of unifying theory, as the other two commentators do. Tait productively points out that the PB theory of pain has not sufficiently addressed social factors in pain. However, we wish to suggest with this analysis that the theory is capable of dealing with such topics in a detailed manner. But it is not possible to do so in one article. In this context it is important to understand the nature of the "framework theory," a concept that is developed in our article and will be addressed in our comments to the next commentator. Briefly, however, the framework theory in its first formulation sets forth concepts and principles in a form that is applicable to each of the areas with which it deals. But it cannot deal in detail with all of the elements of knowledge (findings, concepts, methods, phenomena) in each area. At the beginning only a first sampling can be made that indicates the theory's relevance for the area. Later elaborations of the theory must progressively deal with the additional elements of knowledge in the area [9]. This is one of the reasons the framework theory is heuristic, because it calls for additional analysis and research to complete its structure. It is important to evaluate our field's development historically and understand its stage of development compared to other more developed sciences. Before each of science's unifying theories was formulated, most. of the scientists of the time would have expressed sentiments like those of Tait, that unification "will require more knowledge than we have now:' Most scientists work in specific areas (and in doing so contribute important science products). Most such scientists are not interested in working

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on the construction of large overarching theory structures, and their specialized contact with the field may leave them with doubt about the possibilities of such an endeavor. However, despite the value of their own specific work, this is not a productive orientation to have in assessing the value of a new overarching theory.

SPECIALIZED THEORY OR UNIFIED THEORY? (RESPONSE TO JENSEN) Let us begin by indicating that Jensen's analysis and comments are very productive, as has been the case with the two preceding reviewers. Moreover, there is considerable commonality between the PB theory of pain and the Fordycean behavioral theory of pain that is based on Skinner's behaviorism-which appears to be the operant approach that Jensen employs. We recognize the value of Fordyce's behavioral theory, for what it has done in the past, for its value in contemporary use, and for serving as the foundation for Jensen's productive thoughts. But Skinner's theory was formulated in basic form over 50 years ago, in the context of animal laboratory studies. The modern study of human behavior in the learning behavioral framework did not begin until the mid 1950s, when psychological behaviorism and other behavioral works began a new generation of developments. As important a contribution as Skinner's theory was, it lacked very central features, it contained errors and inconsistencies, and it did not provide the best framework possible for dealing with various areas of human behavior, including that of pain. Psychological behaviorism provided some of the fundamental elements in the modern behavioral approach and is a large advance over Skinnerian behaviorism. One example especially relevant to pain study may be mentioned, that of Skinner's treatment of emotion. His position stems from his basic theory, which is that there are two types of conditioning, the classical conditioning of emotions and the operant conditioning of behavior (motor responding) [7]. This specification was valuable, but Skinner's interest and methods of study were suited only to one type of conditioning-operant conditioning.* So he took the position that classical conditioning and emotions are not important and stated

'Skinner considered the effect on behavior of the contingent presentation of a positive reinforcer as one case and the contingent removal of a negative reinforcer as the other case for strengthening behavior. However, PB recognizes that contingent presentation and removal apply to both positive and negative reinforcers. And, depending on the type of presentation and type of reinforcer, behavior may be either strengthened or weakened. So Skinner's terminology does not cover the events to be dealt with, and this and other things call for the types 'of changes in basic conception and terminology that PB makes.

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explicitly that emotional responding does not affect behavior. Radical behav iorism, as a consequence, to this day has never studied classical conditioning and emotions and how emotions can affect behavior and does not accept the concept of emotion in such a role. This fundamental theo retical position has put radical behaviorism at odds with (isolated from) every other approach that recognizes emotion as an important determinant of human behavior. To continue , Jensen makes a central point in describing the isolation of the different approaches to the study of pain. Specifically, he mentions the lack of relationship shown in articles in Pain and Pain Forum between those studying psychological matters and those studying biological matters. The disunity is even deeper than that ; for example, those who take a cognitive viewpoint (like the social constructionists) do not relate their work to those who take a behavioral viewpoint (like the operant approach). Actually, each approach sets itself forth separately. Not only do they not relate to the other theories, they typically do not deal with the phenomena dealt with by other theories. Thus the social constructionists do not deal with the pain behaviors of interest to those supporters of the operant approach. And the operant principles are not appropriate for dealing with the effects of culturally produced attitudes and emotions on pain. Typically, also, the several views derogate each other, rather than looking for unification. Psychological behaviorism, unlike radical behaviorism, has been constructed in the context of human behavior as well as animal studies. It has shown in laboratory study that classical conditioning of emotion very importantly affects behavior and has constructed on this basis a set of basic principles of classical and operant conditioning that indicates how they are related. In doing so, PB provides a basic theory by which to unify the studies of various aspects of human behavior that cannot be so considered within Skinner's operant behaviorism. The PB theory of pain has taken advantage of those characteristics in formulating its unified approach. Jensen sees the value of how the PB theory of pain provides a unification between the psychology of pain and the role of emotion. He also states that "Another strength of the psychological behaviorism model of pain is its focus on personality and the relationships between personality and other components of the pain phenomenon." This is an important position. For Skinner, as all the behaviorists in his generation , was an animal researcher and did not study personality or formulate a theory of personality. The PB pain theory thus can unify interests in the study of pain that until this time have remained separate and competitive. However, while Jensen recognizes the theory's power for unification in these two areas, he does not see the

possibilities in other areas. And to some extent he makes a productive criticism here. That is, he points out that the unified theory of PB is not complete in that the biological and social aspects of the theory are not as developed as the psychological aspects. And, despite the fact that Jensen recognizes the importance of the pain theory's unification of the psychological-behavioral and the behavioral-personality levels of the study, he nevertheless concludes "Where I believe the approach of Staats et al. may be weakest is in the assertion that psychological behaviorism provides a foundation for a unified theory of pain." Jensen goes on to set forth his position that rather than attempt to construct unified theory in the area of pain, within which there are various phenomena to be studied and hence various approaches, the goal should be deepening the study of the separate approaches. Work done in these approaches will in his view provide the best fund of knowledge that science can offer. Let us respond , first, by saying that this position flies in the face of the history and philosophy of science. In every science area that has unified knowledge, at one time there were separate areas of study, each with its own approach. Kuhn in describing the early study of electrical phenomena stated "there were almost as many views about the nature of electricity as there were important electrical experimenters" [5] and then goes on to indicate how progress was made in establishing relationships among the views to attain a unified paradigm. Shapere [The nature of scientific change. In mimeograph , 1977] described how electricity, magnetism, light, and chemical phenomena were first studied separately but over a long period they came to be joined into a unified theory framework that yielded enormous advancement and productivity. Let us also quote a prominent philosopher of science in this area. The aim of scientific explanation throughout the ages has been unification, i.e., the comprehend ing of a maximum of facts and regularit ies in terms of a minimum of theoretical concepts and assumptions. The remarkable success achieved, especially in the theories of physics, chemistry, and to some extent biology, has encouraged pursuit of a unitary system of explanatory premises [3, p.12]. Along with its foundation in biological science , the field of pain includes behavioral , psycholog ical, and social areas of study, each of which is still in a disunified state of science described by Kuhn and other historians of science. Different terms , principles , methods of study, and findings are dealt with in the cognitive, cognitive-behavioral, and biological theories of pain. The disjunctions that result are enormous in number and in the

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inefficiency that results for the student, researcher and clinician. (For example, Jensen points out the difference of the term negative reinforcer in PB and Skinner's behaviorism. We can see another example in the various terms that Sullivan employs-for example, in differentiating attitudes, emotions, feelings, and pain-with no indication of their commonality) . Because of this disunity, rather than learning one theory language, many have to be learned. The problems of translation are horrific. There are many drawbacks to disunified science. And there are many advantages to unified theory. For example, when a theory is formulated that relates two formerly separate areas of study, it is usual that higher level principles and concepts are derived. An example in the present theory is that of basic behavioral repertoire. That concept could be used to unify behavioral principles with the study and measurement of personality. The concept and principles are not to be found in either area when they are separated. It is also typical for higher-level principles and concepts to provide new directions of empirical research. Does the unified theory subtract from the work of the original, separate theory-research areas? Not at all. The fact is that the importance of the compound developments that are included within a unified theory are enhanced. Spence gives the example of Newton's theory of gravitation that unified concepts such as "Kepler's [laws] concerning planetary motions, Galileo 's law of falling bodies, laws of the tides and so on" [8]. Newton's unifying theory added to rather than subtracted from the importance of the early findings and formulations. Placing the study of the biological, behavioral, psychological, and social study of pain into a unified theory can be expected to be very valuable and to yield new advances. But that does not mean the more specialized approaches are downgraded in the process, or that the PB theory suggests the specialized approaches have lost their potential for gener ating research or guiding clinical practice. The unified theory generally does not displace the more specialized developments but rather employs them in a coordinated way. Relevant to Jensen 's position, let us add that Fordyce (and those working in this tradition) made a large and important contribution in extending Skinner's behaviorism to the study and treatment of pain. We suggest, however, that employment of the PB

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approach would enhance that contribution in future work in this program. To continue, Jensen refers to the contributions that have been made by specialized, delimited pain theories and takes that to mean that the field should continue in that manner, that is, work in constructing a collection of unique but complementary theories. We agree that programs of research in unique separated areas are important. But science moves in the direction of establishing relationships among such areas through formulating more parsimonious yet more general theories that yield greater consensus , more penetrating analysis, and more heuristic value. It behooves the field of pain, with its foot in biological, behavioral, psychological, and social areas of study, to strive for the science progress through unification that has been shown in the more advanced sciences. While, as Jensen notes, this basis for bridging developments is far from complete, a basis is there. It remains for the present authors and for others to develop the components of the theory framework. And there is a huge amount of theoretical, empirical, and methodological work to be done.

References 1. AI-Absi M, Rokke po: Can anxiety help us tolerate pain? Pain 46:43-51, 1991 2. Boeke S, Ouivenvoorden HJ, Verhage F, Zwaveling A: Prediction of pain and duration of hospitalization using two anxiety measures . Pain 45:293-297,1991 3. Feigl H: The "orthodox" view of theories : remarks in defense as well as a critique. In Radner M, and Winokur S (eds): Minnesota studies in the philosophy of science. Vol. 4. University of Minnesota Press, Minneapolis, 1970 4. Hodes RL, Howland E, Lightfoot N, Cleeland CS: The effects of distraction on cold pressor gain. Pain 1:109-114, 1990 5. Kuhn TS: The structure of scientific revolutions. 2nd ed. The University of Chicago Press, Chicago, 1962 6. McCaul KO, Malott JM: Distraction and coping with pain. Psychological Bull 95:516-533, 1984 7. Skinner BF: The steep and thorny way to a science of behavior. Am Psychol 30:42-49, 1975 8. Spence KW: The nature of theory construction in contemporary psychology. Psychol Rev 51:47-68, 1944 9. Staats AW: Behavior and personality. Springer, New York, 1996