J O U R N A L OF
Personality Social Psychology Volume 37
January 1979
Number 1
Stressful Life Events, Personality, and Health: An Inquiry Into Hardiness Suzanne C. Kobasa University of Chicago Personality was studied as a conditioner of the effects of stressful life events on illness onset. Two groups of middle and upper level executives had comparably high degrees of stressful life events in the previous 3 years, as measured by the Holmes and Rahe Schedule of Recent Life Events. One group (n = 86) suffered high stress without falling ill, whereas the other (n = 75) reported becoming sick after their encounter with stressful life events. Illness was measured by the Wyler, Masuda, and Holmes Seriousness of Illness Survey. Discriminant function analysis, run on half of the subjects in each group and cross-validated on the remaining cases, supported the prediction that high stress/low illness executives show, by comparison with high stress/high illness executives, more hardiness, that is, have a stronger commitment to self, an attitude of vigorousness toward the environment, a sense of meaningfulness, and an internal locus of control. gested that stressful life events precipitate somatic and psychological disease. This article considers the importance of personality as a conditioner of the illness-provoking effects of stress. During the last decade, investigators have shown that the recent life histories of hospitalized persons contain significantly more frequent and serious stressful events than do histories of matched controls from the general population (e.g., Paykel, 1974) and that Navy personnel who begin a cruise with high stress scores suffer more illness episodes during the months at sea than do sailors who start out with low stress scores (Rahe, 1974). But the possibility of a causal connection between stress and illness is hardly a new idea. Physicians, philosophers, and persons simply
An exceptional number of studies in the last 20 years (cf. Dohrenwend & Dohrenwend, 1974; Gunderson & Rahe, 1974) have sugThis article is based on the author's doctoral dissertation (Kobasa, 1977), submitted to the Department of Behavioral Sciences at the University of Chicago. The preparation of this manuscript was supported in part by Public Health Service Grant MH28839-01 from the National Institute of Mental Health. The author wishes to thank Robert R. J. Hilker, James Kennedy, and all of the executives who participated in the study. Special appreciation is extended to Salvatore R. Maddi who supervised the project. Chase P. Kimball, David E. Orlinsky, and Marvin Zonis contributed many useful suggestions as dissertation committee members. Requests for reprints should be sent to Suzanne C. Kobasa, Department of Behavioral Sciences, University of Chicago, 5848 S. University Avenue, Chicago, Illinois 60637.
Copyright 1979 by the American Psychological Association, Inc. 0022-3514/79/J701-0001S00.75
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SUZANNE C. KOBASA
concerned about staying healthy have long wondered about the etiological significance of life events. The distinctiveness of recent research lies in its attempt to define and measure stress. In the current studies, a life event is denned as stressful if it causes changes in, and demands readjustment of, an average person's normal routine. This definition of stress has relied upon the empirical demonstration (Holmes & Masuda, 1974; Holmes & Rahe, 1967) that there is a general consensus about the degree to which specific life occurrences involve change and require readjustment. This consensus emerged from the ratings of stressfulness of a long list of events made by thousands of subjects varying in age, sex, socioeconomic status, race, cultural background, education, and religion. From this consensus, stressfulness weights for the life events were obtained. Deriving from this research is the Schedule of Recent Life Events (Holmes & Rahe, 1967), which contains positive (e.g., marriage), negative (e.g., illness of a family member), frequent (e.g., minor traffic violation), and rare (e.g., death of a child) occurrences. The associated Social Readjustment Rating Scale (Rahe, Lundberg, Theorell, & Bennett, 1971) gives the consensual weights for these events (e.g., on a scale from 1 to 100, divorce gets a mean score of 73 and vacation, a score of 13). The stressfulness of a particular person's life is measured in this procedure by finding out what events he or she has encountered and scoring the occurrences according to their consensually quantified weights. This consensual approach to stress as measurable environmental input has allowed easy collection of large amounts of data and uncomplicated analysis of the statistical relationship between stressful life events and illness onset. The findings of stress research have had dramatic impact in both professional journals and popular magazines. In the journals (e.g., Rabkin & Struening, 1976), one usually finds some caution urged about too quickly concluding a causal relationship between stress and illness on the basis of correlational and methodologically weak studies.
This warning is mitigated, however, by a sense of optimism that there is something to this stress and illness connection and a wish for studies that are more sophisticated in design and methods of analysis. But in the popular literature (e.g., Wolfe, 1972), final conclusions have already been drawn. Readers are provided with a self-administered stress test and told the likelihood of illness associated with each total stress score (e.g., a score above 300 means an 80% chance of getting sick). Readers whose stress scores are high are warned that if they wish to remain healthy they should avoid additional stressful encounters, even to the point of shunning such everyday necessities as driving on the Los Angeles Freeway. This advice seems inadequate, insofar as modern life can be characterized as inherently stressful (Brodsky, 1977; Toffler, 1970). A person might indeed be able to keep from getting married or taking on a new mortgage, but how can one prevent the effects of pollution and overcrowding or of being assigned to a different job when his or her company signs a new contract? Further, increasing levels of stress tend to coincide with increasing opportunities and potential resources (Kobasa, Hilker, & Maddi, Note 1). By avoiding stress, modern persons may be turning away from a chance to better their lives. Before deciding to avoid stressful life at any cost, one should consider the actual magnitude of the relationship between stress and illness. Although correlations range from .20 to .78, the majority fall below .30, and in Rahe's naval data, the correlations are consistently around .12 (Rabkin & Struening, 1976). Many stress and illness researchers, in their preoccupation with group means, have failed to question the distribution of their data. Variability of both stress and illness scores within groups has been observed to be extreme in several studies (Wershow & Reinhart, 1974). One likely explanation for these data is the presence of subjects with high stress scores who are not getting sick. Oddly, such subjects have been overlooked in the popular and professional literature on stress and illness.
STRESSFUL LIFE EVENTS
Studying Stressed but Healthy Persons
ness of authentic living, White (1959) on competence, Allport (1955) on propriate In contrast, the present study considers striving, and Fromm (1947) on the produchow highly stressed subjects who remain tive orientation. Hardy persons are considered healthy differ from those who show illness to possess three general characteristics: (a) along with high stress. Studying the individual the belief that they can control or influence who undergoes high degrees of stress without the events of their experience, (b) an ability falling ill amounts to inquiring about the to feel deeply involved in or committed to the mediating factors that affect the way one re- activities of their lives, and (c) the anticipaacts to stress. Holmes and Masuda (1974) tion of change as an exciting challenge to and the majority of other stress investigators further development. Much research has alattempt to draw a direct causal link between ready shown the advantages in behavior of the occurrence of stressful life events and the control (e.g., Lefcourt, 1973; Rodin & Langer, onset of illness by reference to the physio- 1977; Rotter, Seeman, & Liverant, 1962; logical model of a stress reaction formulated Seligman, 1975), commitment (e.g., Antonovby Hans Selye (1956). Stressful life events sky, 1974; Kobasa & Maddi, 1977; Lazarus, are said to evoke "adaptive efforts by the hu- 1966; Lazarus, Averill, & Opton, 1974; Moss, man organism that are faulty in kind or dura- 1973), and challenge (Fiske & Maddi, 1961; tion, lower 'bodily resistance' and enhance the Maddi, 1967). In discussing the hypotheses probability of disease occurrence" (Holmes presented below, the implications of theory & Masuda, 1974, p. 68). Holmes and others, and research concerning these three general however, fail to take into account what Selye characteristics are extended to considerations goes on to say about individual differences of health and illness. and the stress reaction. In the study described Hypothesis 1. Among persons under stress, in this article, the more subtle points in those who have a greater sense of control Selye's work are referred to, in the attempt over what occurs in their lives will remain to consider factors in the stress reaction that healthier than those who jeel powerless in the serve to deflect the negative impact of stress- face of external forces. Following the model ful events. Mediators of the stress and illness proposed by Averill (1973) to explain his connection, which probably include physio- laboratory observation that some organisms logical predisposition, early childhood experi- are not debilitated by stressful stimuli, the ences, and social resources, as well as the highly stressed but healthy person is hypothemediator emphasized here, personality, are to- sized to have (a) decisional control, or the gether responsible for what Selye calls the capability of autonomously choosing among distinctive way in which each individual various courses of action to handle the stress; "takes to" stressful life occurrences. (b) cognitive control, or the ability to interThe proposition of this study is that per- pret, appraise, and incorporate various sorts sons who experience high degrees of stress of stressful events into an ongoing life plan without falling ill have a personality structure and, thereby, deactivate their jarring effects; differentiating them from persons who become and (c) coping skill, or a greater repertory sick under stress. This personality difference of suitable responses to stress developed is best characterized by the term hardiness. through a characteristic motivation to achieve The conceptual source of the supposition, in across all situations. In contrast, the highly contrast to the passive and reactive view of stressed persons who become ill are powerless, humankind found in most stress and illness nihilistic, and low in motivation for achievework, is a set of approaches to human bement. When stress occurs, they are without havior that Maddi (1976), in his categorization of the major personality theories, calls recourse for its resolution, give up what little fulfillment theories. The hardy personality control they do possess, and succumb to the type formulated here builds upon the theoriz- incapacity of illness. Hypothesis 2. Among persons under stress, ing of existential psychologists (Kobasa & those who feel committed to the various areas Maddi, 1977; Maddi, 197S) on the strenuous-
SUZANNE C. KOBASA
of their lives will remain healthier than those who are alienated. Committed persons have a belief system that minimizes the perceived threat of any given stressful life event. The encounter with a stressful environment is mitigated by a sense of purpose that prevents giving up on one's social context and oneself in times of great pressure. Committed persons feel an involvement with others that serves as a generalized resistance resource against the impact of stress (Antonovsky, 1974). Committed persons have both a reason to and an ability to turn to others for assistance in times demanding readjustment. Although commitment to all areas of life— work, social institutions, interpersonal relationships, family, and self—should be characteristic of highly stressed persons who do not fall ill, one area is singled out as particularly important for health. Staying healthy under stress is critically dependent upon a strong sense of commitment to self. An ability to recognize one's distinctive values, goals, and priorities and an appreciation of one's capacity to have purpose and to make decisions support the internal balance and structure that White and other theorists (cf. Coelho, Hamburg, & Adams, 1974) deem essential for the accurate assessment of the threat posed by a particular life situation and for the competent handling of it. Hypothesis 3. Among persons under stress, those who view change as a challenge will remain healthier than those who view it as a threat. Persons who feel positively about change are catalysts in their environment and are well practiced at responding to the unexpected. Because they value a life filled with interesting experiences, change seekers have well explored their environment and know where to turn for resources to aid them in coping with stress. They have a predisposition to be cognitively flexible, which allows them to integrate and effectively appraise the threat of new situations. Their basic motivation for endurance allows them to persist even when the new information is exceedingly incongruous and, thereby, maximally provoking of strain and illness (Moss, 1973). Given the characterization of hardiness contained in the first two hypotheses, it should
be clear that the highly stressed but healthy individual is not engaging in irresponsible adventurousness. At the core of the search for novelty and challenge are fundamental life goals that have become, in adulthood, increasingly integrated in a widening diversity of situations (Henry, 1968; Neugarten, 1974). Although personality is the primary concern of the study reported here, other kinds of variables may well differentiate the highly stressed and healthy from those who have fallen ill under stress. These would include a variety of psychological, social, physiological, and environmental mediators. In order to increase understanding of those who fall ill and stay healthy under high stress, the present study included information concerning various demographic characteristics and perceptions of stressfulness of events. Method Overview The first task was the identification of high stress/ low illness and high stress/high illness groups. For this purpose, all members (# = 837) of a large subject pool were mailed a stress and illness questionnaire. They were asked to report, by month and year, which of a list of stressful life events and illness episodes they had experienced in the previous 3 years. A total stress score and a total illness score were obtained for each subject by the standard procedure of noting the items checked and multiplying these by their frequencies and consensually denned weights. Subjects were then assigned to one of the two groups or put aside. Assigned to the high stress/ low illness and high stress/high illness groups were 126 subjects above the median for total stress and below the median for total illness and 200 subjects above the median for total stress and above the median for total illness, respectively. Discarded subjects included 322 low-stress cases and 22, or all, of the female subjects. In further group refinement, 40 high stress/high illness cases whose peak illness score preceded rather than followed their peak stress score and 10 borderline cases from each of the two groups were put aside. Finally, because of a request from the company for which all of the subjects worked that the sample to be administered personality questionnaires be kept at a workable minimum, a set of 100 subjects was randomly selected from the 116 remaining high stress/low illness cases and 100 randomly selected from the 150 remaining high stress/high illness subjects. Within 3 months of the stress and illness testing, the two groups were mailed another questionnaire. This questionnaire contained several personality tests,
STRESSFUL LIFE EVENTS along with questions about demographics and perception of life stressfulness. The data from approximately half of each group were used to test hypotheses concerning group differences in hardiness. Data from the remaining cases in each group were used to cross-validate the results. The division of the groups into test and crossvalidation cases was necessitated by the statistical technique relied upon in the study, discriminant function analysis, which has been characterized in previous research by problems of generalizability due to instability of results (cf. Huberty, 1975). Although powerful as a tool for looking at group differences, discriminant function analysis, like regres sion analysis, has not always provided results that hold up in the making of inferences from sample results to some population, and over repeated samplings. Until a replication of the study is possible, the use of a "holdout sample" must be relied upon for an accurate test of the adequacy of the derived discriminant function that defines group differences.
Subjects This study required a subject pool both large and stressed enough to obtain sufficiently large groups for study. All of the middle and upper level executives of a large public utility served as the pool from which groups were selected. This utility, in the year prior to the onset of the study, had entertained serious discussion (in executive seminars, company publications, and consultations with the medical department) of the increasing numbers of stressful events faced by executives. These events consisted of changes instituted by the utility itself, like a program of job evaluations that led to some promotions and many more demotions, as well as requirements for readjustment from external sources, such as the federal government's affirmative action demands. These changes, coupled with the expected usual range of personal and family stresses, suggested that stress scores for the subject pool would be generally high. Demographically, the pool was quite homogeneous. The modal characteristics of the subjects were (a) male gender; (b) 40 to 49 years of age; (c) married, with two children; (d) on the third or middle management level, and having been there for 6 years or more; (e) possessing at least a college degree; (f) wife not working outside the home; (g) usually Protestant, and attending religious services very or fairly often.
Measurement oj Stress and Illness The most frequently used scales in stress and illness research, the Schedule of Recent Life Events and the Social Readjustment Rating Scale (Holmes & Rahe, 1967), were employed in this study. Additions to these scales were made on the basis of pilot testing. The majority of additions were more detailed specifications of the original items, modeled after suggestions from other adapters of the test (Hough, Fairbank, & Garcia, 1976; Paykel, 1974).
Each of the most ambiguous events was replaced by two events, one presenting the positive form of the Holmes and Rahe item and the other, the negative version. "Change in financial state," for example, was translated into "improvements in financial state" and "worsening of financial state." These specifications were given the seriousness weights of the items from which they were derived. Other additions to the Holmes and Rahe list were based on a pilot use of the test with SO randomly selected executives. In response to the question "What other events have you experienced during the past 3 years?", these subjects reported 15 events not found on the original list. Most of these referred to occurrences at work. Seriousness weights were assigned to these additions by the investigator and 20 other judges using the ratio scale judgment procedure of Holmes and Rahe (1967). The illness items in the stress and illness questionnaire were taken from the Wyler, Masuda, and Holmes (1968) Seriousness of Illness Survey. After consultation with the medical director of the executives' company, 118 of the diseases listed in this survey were chosen as applicable to the pool being tested. Each illness item is characterized by a seriousness weight based on a consensual agreement of numerous and diverse judges (both medical and lay) and is obtained in a manner similar to the derivation of the Social Readjustment Rating Scale. The reliability and validity of this scale as a complete listing of disease syndromes in a form accessible to both laypersons and physicians, and as an accurate set of evaluations of the general seriousness of various distinct illnesses, has been established (cf. Wyler, Masuda, & Holmes, 1970).
Measurement of Personality, Demographic, and Perception Variables A composite questionnaire, made up of all or parts of four standardized and two newly constructed instruments, was designed to test the three personality hypotheses. The standardized tests were chosen for their theoretical relevance and empirical reliability and validity. All of the instruments are appropriate for use with a sample of executives (i.e., a group of well-educated adult professionals who are relatively free of gross psychopathology). The control dimension was measured through four different instruments. What has been called decisional control or autonomy was measured through the Internal-External Locus of Control Scale (Lefcourt, 1973; Rotter, Seeman, & Liverant, 1962), and the Powerlessness versus Personal Control scale of the Alienation Test (Maddi, Kobasa, & Hoover, Note 2). The latter instrument also provided a way of measuring cognitive control (i.e., the ability to find meaning in stressful life events) in its Nihilism versus Meaningfulness scale. Coping skill (i.e., the availability of responses with which to deal with stressful life events) was measured through the Achievement scale of the Personality Research Form (Jackson, 1974; Wiggins, 1973).
SUZANNE C. KOBASA
6
The question of whether these forms of control are accompanied by a need to dominate the behavior of others was addressed through administration of the Leadership Orientation scale of the California Life Goals Evaluation Schedules (Hahn, 1966) and the Dominance scale of the Personality Research Form (Jackson, 1974). The commitment dimension was measured by the Alienation Test (Maddi et al., Note 2). Of relevance here are the alienation versus commitment scores this test yields in five areas of functioning (work, social institutions, interpersonal relationships, family, and self). The degree of consistency across a subject's different forms of involvement was also tested. This was done through the Role Consistency Test, adapted from the Gergen and Morse (1967) SelfConsistency Test to measure the compatibility among the subject's reported five most important life roles. Measurement of the orientation to challenge required the administration of several tests. The degree to which the executive sought out rather than avoided stimulation from his environment was measured through the Preference for Interesting Experiences scale of the Hahn (1966) test and the Vegetativeness versus Vigorousness scale of the Alienation Test. The executive's ability to seek challenge even in the face of potential psychological, social, and biological threat was indexed by Hahn's scale of Security Orientation. Cognitive flexibility versus cognitive rigidity was measured through the Need for Cognitive Structure scale of the Personality Research Form and the ability to persist even in the most challenging environment, through the Need for Endurance scale of the same instrument. Finally, the degree to which an orientation toward challenge was characterized by a general sense of responsibility toward life's demands was measured through the Adventurousness versus Responsibility scale of the Alienation Test. Subjects were asked about three demographic characteristics: age, job level (third, fourth, fifth, and officer), and number of years spent at current level. Executives were also asked to rate on a scale of 1 (not at all stressful) to 7 (extremely stressful) how stressful they usually think each of the following areas of life is: work, financial concerns, social/community involvements, interpersonal relationships, family, and personal or inner-life concerns.
Results Stress and Illness Scores Of the 837 executives who were contacted by mail, 670 (80%) returned completed stress and illness questionnaires. The mean stress score was 399, with a standard deviation of 162, a range from 0 to 2,239, and a median of 306. The mean illness score was 913, with a standard deviation of 1,115, a range from 0 to 6,900, and a median of 550. Comparison of these executives' scores with norms availa-
ble in the literature (Holmes & Masuda, 1974; Wyler et al., 1968, 1970) indicates that on the average, they had experienced a moderate amount of illness (comparable to the threat of life and discomfort associated with having a peptic ulcer or high blood pressure) in the previous 3 years. During this period, they had, on the average, also encountered sufficient change and demands for readjustment in their lives to constitute major life crisis (what Holmes has associated with an 80% likelihood of getting seriously ill in the near future). A Pearson product-moment correlation of .24 (p < .025) was obtained between the total stress and total illness scores. Canonical correlations were also run to determine whether a stronger relationship might be obtained. Stress scores—both the standard weighted scores and simple frequencies—for various areas of life (work, home, community, etc.) were used as the predictor, and illness scores —both weighted and frequencies—for various body systems (cardiovascular, respiratory, etc.) were used as the criterion set. Neither analysis of unweighted stress events and illnesses nor correlations of selected types of stress with selected types of illness, however, significantly strengthened the statistical relationship between stress and illness. The weak, but significant, correlation of .24 is consistent with most of the available research reports (Rabkin & Struening, 1976). Testing oj Group Differences Completed personality questionnaires were returned by 86% of trie high stress/low illness and 75% of the high stress/high illness subjects. Forty "test" subjects were randomly selected from each group for analysis of differences across personality, demographic, and perception variables, and 81 subjects were put aside for cross-validation purposes. Mean differences between the test subjects of the two groups were evaluated by t test. None of the demographic variables and only one of the perception variables yielded significant differences, whereas several of the personality variables did so. Further evaluation of group differences was achieved by a
STRESSFUL LIFE EVENTS Table 1 Differences
Between High Stress/Low Illness* and High Stress/High Illness* Executives High stress/ low illness
High stress/ high illness
M
SD
196.05 133.61 5.92 4.10 301.15 188.93 16.50 2.10 14.60 3.26 33.47 7.34
281.02 7.90 388.47 15.12 13.85 34.63
169.86 4.61 188.44 3.20 4.46 6.80
2.49** 2.03* 2.11* -1.20 .86 .73
.73 .22 — — — .43
102.35 117.24 181.67 122.04 256.02 162.76 158.47 139.02 202.15 100.21 29.22 6.42
219.15 185.77 223.73 175.09 316.10 165.24 198.72 144.33 226.95 133.93 29.50 6.44
3.36** 1.22 1.64 1.27 .94 .19
1.04 .43
155.50 21.11 13.35 269.00 15.97 34.97 3.00
216.27 22.19 14.10 337.54 14.37 32.52 3.83
1.98* .34 1.10 1.78* -.96 -.92 2.46**
.99 .35 .21 — —.
f
Variable Control Nihilism External locus of control Powerlessness Achievement Dominance Leadership Commitment Alienation from self Alienation from work Alienation from interpersonal Alienation from family Alienation from social Role consistency Challenge Vegetativeness Security Cognitive structure Adventurousness Endurance Interesting experiences Perception of personal stress
Standardized discriminant function coefficient
* value
M
SD
140.24 6.33 2.81 164.58 2.35 6.83 1.21
160.94 8.60 2.85 174.95 3.19 7.02 1.73
— — — .30
.43
Note. For all variables, the higher the number, the greater the degree of the variable observed. Superior hardiness is indicated by higher scores on achievement, role consistency, endurance, and interesting experiences, and lower scores on nihilism, external locus, powerlessness, dominance, leadership, alienation (from self, work, social institutions, interpersonal relationships, and family), vegetativeness, security, cognitive structure, and adventurousness. A subject's scores on all areas of alienation, measured by the Alienation Test, have a possible range of 0 to 1,200. Vegetativeness, nihilism, powerlessness, and adventurousness scores, also from the Alienation Test, may range from 0 to 1,500. External locus has a low of 0 and an upper limit of 23. The scales taken from the Jackson test—achievement, dominance, cognitive structure, and endurance—have a minimum value of 0 and a maximum of 20. The California Life Goals scale—leadership, security, and interesting experiences—may range from 0 to 60. Role consistency has a low of 0 and a high of 40; perception of personal stress can range from 0 to 7. a « = 40. * p < .05. ** p < .01. discriminant function analysis done on all the personality variables plus the one perception variable that yielded a significant t score. After all data are transformed into standard scores, discriminant function analysis computes a discriminant equation, or a linear combination of weighted variables that produces the greatest statistically derivable distance between the two groups. The larger the weighting or discriminant coefficient of a variable, the more powerful it is as a group discriminator. Table 1 presents all variables submitted to
discriminant function analysis and their summary statistics, including significance of difference between groups established by t test. The results demonstrate that high stress/low illness executives can be distinguished from high stress/high illness subjects. The 11 variables for which a standardized discriminant function coefficient is provided in the table combine to form a significant function, with a Wilks's Lambda of .64, significant at the .001 level, and a canonical correlation of .60. The Wilks's Lambda (see Huberty, 1975) is a measure of the original variable's discrimi-
SUZANNE C. KOBASA
nant power, before it is removed by the discriminant function. The canonical correlation is a measure of the association between the single discriminant function and the set of dummy variables that defines the two group memberships. Given the composition of this function, the general position concerning hardiness is confirmed. High stress/low illness executives are, at least in some ways, more in control, more committed, and more oriented to challenge than are high stress/ high illness executives. Looking at the variables that make the most significant contribution to the discriminant equation and that are also responsible for significant mean differences, the high stress/low illness executives are distinguished by their sense of commitment to (or lack of alienation from) self, their sense of vigorousness (as opposed to vegetativeness) about life, their sense of
meaningfulness (as opposed to nihilism), and their internal (as opposed to external) locus of control. One perception-of-stress variable joins the important personality discriminators—high stress/low illness executives find the personal sphere of their lives significantly less stressful then do the high stress/high illness subjects. Several personality variables appear to contribute to the discriminant equation even though they do not yield significant mean differences by t test. Although it is risky to interpret the discriminant coefficients of these variables, it is worth noting that the direction of mean difference is in general consistent with the hypotheses concrening hardiness as an insulation against illness. Along with their analytic function, the discriminant coefficients also serve a classificatory and validation purpose. Multiplying a
Table 2
Differences Between All High Stress/Low Illness11 and All High Stress/High Illnessb Executives
Variable Control Nihilism External locus of control Powerlessness Achievement Dominance Leadership Commitment Alienation from self Alienation from work Alienation from interpersonal Alienation from family Alienation from social Role consistency Challenge Vegetativeness Security Cognitive structure Adventurousness Endurance Interesting experiences Perception of personal stress • n = 86. *> n = 75. * p < .05. ** p < .01.
High stress/ low illness
High stress/ high illness
M
SD
M
SD
value
217.01 5.38 314.95 16.40 14.35 33.89
141.03 3.90 190.65 2.35 3.38 6.56
262.23 7.51 364.20 15.95 14.27 34.53
161.77 4.60 189.50 3.03 4.19 6.29
1.82* 2.05* 1.82* -1.02 -.13 .54
113.87 180.61 276.53 168.93 205.39 28.80
122.66 129.22 159.95 145.83 98.37 6.78
180.56 201.68 309.64 200.99 219.28 29.59
150.65 159.69 151.54 144.62 123.45 6.84
2.97** .89 1.30 1.35 .76 .71
160.04 21.52 13.16 276.88 15.01 34.29 2.72
133.34 6.83 2.77 165.58 2.95 6.31
215.26 22.63 13.75 330.84 14.53 32.80
1.82*
1.31
3.61
153.54 7.43 2.94 158.91 3.15 7.00 1.79
.95 1.26 1.78* -.96 -1.37
3.48**
STRESSFUL LIFE EVENTS
subject's scores on the discriminating variables by the associated coefficients allows one to predict the likelihood of the subject's membership in each of the groups. As a test of the classificatory power of the derived discriminant equation, its coefficients are (a) reapplied to the test subjects used to derive the equation and (b) applied to the scores of the "holdout" cases. The discriminant function presented in Table 1 shows predictive capability both internally and externally. Applying the unstandardized versions of the discriminant function coefficients to the raw scores used to derive the function, 78% of the "test" cases are correctly classified (80% of the high stress/low illness executives and 75% of the high stress/high illness subjects). This significantly correct (p < .025) classification is matched in the external cross-validation. Using the unstandardized coefficients on the raw data from the "holdout" subjects, 35 hits (77%) and 21 hits (60%) in the high stress/low illness and high stress/high illness groups, respectively, are realized (p < .05). These cross-validation results offer support for the stability and generalizibility of the results obtained through discriminant function analysis. An examination of the statistics for the entire sample (test cases plus holdouts), which are notably similar to those of the test cases in Table 1, illustrates the strength of the discriminant analysis. Table 2 presents the mean values, standard deviations, and t values for the full high stress/low illness and high stress/high illness groups. Discussion This study of persons who do not fall ill despite considerable stress suggests that personality may have something to do with staying healthy. Using the five most significant discriminators of the high stress/low illness executives (i.e., the variables that contribute to the discriminant equation and produce significant ts) one can speculate on what happens when the hardy individuals meet a stressful life event—how they evaluate the threat posed by the event and cope with it. A male executive having to deal with a job transfer will serve as an example. Whether hardy or not, the executive will anticipate and
experience the changes that the transfer will bring about—learning to cope with new subordinates and supervisors, finding a new home, helping children and wife with a new school and neighborhood, learning new job skills, and so on. The hardy executive will approach the necessary readjustments in his life with (a) a clear sense of his values, goals, and capabilities, and a belief in their importance (commitment to rather than alienation from self) and (b) a strong tendency toward active involvement with his environment (vigorousness rather than vegetativeness). Hence, the hardy executive does more than passively acquiesce to the job transfer. Rather, he throws himself actively into the new situation, utilizing his inner resources to make it his own. Another important characteristic of the hardy executive is an unshakable sense of meaningfulness and ability to evaluate the impact of a transfer in terms of a general life plan with its established priorities (meaningfulness rather than nihilism). For him, the job transfer means a change that can be transformed into a potential step in the right direction in his overarching career plan and also provide his family with a developmentally stimulating change. An internal (rather than external) locus of control allows the hardy executive to greet the transfer with the recognition that although it may have been initiated in an office above him, the actual course it takes is dependent upon how he handles it. For all these reasons, he is not just a victim of a threatening change but an active determinant of the consequences it brings about. In contrast, the executive low in hardiness will react to the transfer with less sense of personal resource, more acquiescence, more encroachments of meaninglessness, and a conviction that the change has been externally determined with no possibility of control on his part. In this context, it is understandable that the hardy executive will also tend to perceive the transfer as less personally stressful than his less hardy counterpart. The mechanism whereby stressful life events produce illness is presumably physiological. Whatever this physiological response is, the personality characteristics of hardiness may cut into it, decreasing the likelihood of
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SUZANNE C. KOBASA
breakdown into illness. Needless to say, description of the actual nature of physiological mechanisms and their links to personality and stressful occurrences will have to wait for more sophisticated stress research. Until then, however, two alternative explanations of the present results should be considered. It could be argued that there is a spurious factor at work in the subjects' completion of questionnaires, one that determines what they say about personality, stress levels, and illness experience. Mechanic (1976) has discussed the possible distortion of stress data by a variable that he calls illness behavior. From Mechanic's perspective, one could suggest that the high stress/high illness executives have not really undergone any physiological breakdown but that they simply want to act and be treated as if they are sick and thereby withdraw from a life situation experienced as too stressful. The best evaluation of this position would come from a study that employs physiological rather than self-report measures of illness and monitors physiological states before and after the occurrence of a stressful life event. Until such studies are available, reliance must be placed on data already collected. Mechanic's explanation seems much more likely to apply to the self-report of mild, vague symptoms than to report of more serious illness. For example, headaches and indigestion might well be reported by subjects engaging in illness behavior. But it seems unlikely that definite illnesses requiring medical diagnosis, such as heart attack, cancer, detached retina, and even hypertension would be erroneously reported. Illnesses of the latter sort are responsible for high illness scores on the self-report instrument used in the present study. It is therefore not likely that the results obtained can be explained completely by the concept of illness behavior. Another alternative explanation would suggest that the observed personality differences between the high stress/low illness and the high stress/high illness executives result from the latter group having experienced illness. Presumably, the high stress/high illness executives were not more alienated, external in beliefs concerning locus of control, and uninterested in change before the illnesses occurred. Their responses to the personality
questionnaire may reflect the psychologically debilitating effects of illness. A prospective, longitudinal study in which stress and personality scores at Time 1 are used to predict illness scores at Time 2 is obviously necessary. But the present study provides some basis for regarding the alternative explanation as less likely than that offered here. Although not discussed in this report, subjects found to be low in stress and high in illness showed personality scores midway between the high stress/low illness and high stress/high illness groups (Kobasa, 1977). It is of specific relevance to the alternative explanation that the low stress/high illness subjects were lower on nihilism, alienation from self, vegetativeness, and external locus of control than were high stress/high illness subjects. This finding indicates that personality questionnaire responses indicative of lack of hardiness are not merely a response to illness. Continued work in the area of stress is essential. There is still much to be learned about the role of personality and other mediators in the connection between stressful life events and illness or health. Should studies incorporating physiological measures and employing prospective designs confirm the present findings, then instead of merely warning persons to avoid stressful lives, social scientists will be able to illuminate ways of developing the personality characteristics that can aid in a productive and healthy life led in the full complexity of modern, urbanized, industrialized societies. Reference Notes 1. Kobasa, S. C., Hilker, R. R. J., & Maddi, S. R. Remaining healthy in the encounter with stress. Paper presented at the meeting of the American Medical Association Congress on Occupational Health, St. Louis, Missouri, September 1977. 2. Maddi, S. R., Kobasa, S. C., & Hoover, M. The Alienation Test: A structured measure of a multidimensional subjective state. Manuscript submitted for publication, 1978.
References Allport, G. W. Becoming: Basic considerations for a psychology of personality. New Haven, Conn.: Yale University Press, 19SS. Antonovsky, A. Conceptual and methodological problems in the study of resistance resources and stressful life events. In B. S. Dohrenwend & B. P. Doh-
STRESSFUL LIFE EVENTS renwend (Eds.), Stressful life events: Their nature and effects. New York: Wiley, 1974. Averill, J. R. Personal control over aversive stimuli and its relationship to stress. Psychological Bulletin, 1973, SO, 286-303. Brodsky, C. M. Long-term work stress in teachers and prison guards. Journal of Occupational Medicine, 1977,19, 133-138. Coelho, G., Hamburg, D. A., & Adams, J. E. (Eds.). Coping and adaptation. New York: Basic Books, 1974. Dohrenwend, B. S., & Dohrenwend, B. P. (Eds.). Stressful life events: Their nature and effects. New York: Wiley, 1974. Fiske, D. W., & Maddi, S. R. (Eds.). Functions of varied experience. Homewood, 111.: Dorsey Press, 1961. Fromm, E. Man for himself. New York: Holt, Rinehart & Winston, 1947. Gergen, K. J., & Morse, S. J. Self-consistency: Measurement & validation. Proceedings of the 75th Annual Convention of the American Psychological Association, 1967, 2, 207-208. (Summary) Gunderson, E., & Rahe, R. (Eds.). Life stress and illness. Springfield, 111.: Charles C Thomas, 1974. Hahn, M. E. California Life Goals Evaluation Schedules. Palo Alto, Calif.: Western Psychological Services, 1966. Henry, W. E. Personality change in middle and old age. In E. D. Norbeck, D. Price-Williams, & W. M. McCord (Eds.), The study of personality: An interdisciplinary appraisal. Chicago: Holt, Rinehart & Winston, 1968. Holmes, T. H., & Masuda, M. Life change and illness susceptibility. In B. S. Dohrenwend & B. P. Dohrenwend (Eds.), Stressful life events: Their nature and effects. New York: Wiley, 1974. Holmes, T. H., & Rahe, R. H. The Social Readjustment Rating Scale. Journal of Psychosomatic Research, 1967,11, 213-218. Hough, R. L., Fairbank, D. T., & Garcia, A. M. Problems in the ratio measurement of life stress. Journal of Health and Social Behavior, 1976, 17, 70-82. Huberty, C. J. Discriminant analysis. Review of Educational Research, 1975, 45, S43-S98. Jackson, D. N. Personality research form manual. Goshen, N.Y.: Research Psychologists Press, 1974. Kobasa, S. C. Stress personality and health: A study of an overlooked possibility. Unpublished doctoral dissertation, University of Chicago, 1977. Kobasa, S. C., & Maddi, S. R. Existential personality theory. In R. Corsini (Ed.), Current personality theories. Itasca, 111.: Peacock, 1977. Lazarus, R. S. Psychological stress and the coping process. New York: McGraw-Hill, 1966. Lazarus, R. S., Averill, J. R., & Opton, E. M., Jr. The psychology of coping: Issues of research and assessment. In G. V. Coelho, D. A. Hamburg, & J. E. Adams (Eds.), Coping and adaptation. New York: Basic Books, 1974. Lefcourt, H. M. The function of the illusions of control and freedom. American Psychologist, 1973, 28, 417^25.
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Maddi, S. R. The existential neurosis. Journal of Abnormal Psychology, 1967, 72, 311-325. Maddi, S. R. The strenuousness of the creative life. In I. A. Taylor & J. W. Getzels (Eds.), Perspectives in creativity. Chicago: Aldine, 197S. Maddi, S. R. Personality theories: A comparative analysis (3rd ed.). Homewood, 111.: Dorsey Press, 1976. Mechanic, D. Stress illness and illness behavior. Journal of Human Stress, 1976, 2, 2-6. Moss, G. E. Illness, immunity, and social interaction. New York: Wiley, 1973. Neugarten, B. L. The middle years. In S. Arieti (Ed.), American handbook of psychiatry. New York: Basic Books, 1974. Paykel, E. S. Recent life events and clinical depression. In E. K. Gunderson & R. H. Rahe (Eds.), Life stress and illness. Springfield, 111.: Charles C Thomas, 1974. Rabkin, J. G., & Struening, E. L. Life events, stress, and illness. Science, 1976,194, 1013-1020. Rahe, R. H. The pathway between subjects' recent life change and their near-future illness reports: Representative results and methodological issues. In B. S. Dohrenwend & B. P. Dohrenwend (Eds.), Stressful life events: Their nature and effects. New York: Wiley, 1974. Rahe, R. H., Lundberg, U., Theorell, T., & Bennett, L. K. The Social Readjustment Rating Scale: A comparative study of Swedes and Americans. Journal of Psychosomatic Research, 1971, SI, 241-249. Rodin, J., & Langer, E. J. Long-term effects of a control-relevant intervention with the institutionalized aged. Journal of Personality and Social Psychology, 1977, 35, 897-902. Rotter, J. B., Seeman, M., & Liverant, S. Internal vs. external locus of control of reinforcement: A major variable in behavior theory. In N. F. Washburne (Ed.), Decisions, values, and groups. London: Pergamon, 1962. Seligman, M. E. P. Helplessness. San Francisco: Freeman, 1975. Selye, H. The stress of life. New York: McGraw-Hill, 1956. Toffler, A. Future shock. New York: Random House, 1970. Wershow, H., & Reinhart, G. Life change and hospitalization—A heretical view. Journal of Psychosomatic Research, 1974,18, 393-401. White, R. W. Motivation reconsidered: The concept of competence. Psychological Review, 1959, 66, 297-333. Wiggins, J. S. Personality and prediction: Principles of personality assessment. Reading, Mass.: Addison-Wesley, 1973. Wolfe, S. W. Avoid sickness—How life changes affect your health. Family Circle, May 1972, pp. 30; 166170. Wyler, A. R., Masuda, M., & Holmes, T. H. Seriousness of Illness Rating Scale. Journal of Psychosomatic Research, 1968, 11, 363-375. Wyler, A. R., Masuda, M., & Holmes, T. H. Seriousness of Illness Rating Scale: Reproducibility. Journal of Psychosomatic Research, 1970, 14, 59-64. Received January 9, 1978 •
Personality Social Psychology Volume 37
January 1979
Number 1
Stressful Life Events, Personality, and Health: An Inquiry Into Hardiness Suzanne C. Kobasa University of Chicago Personality was studied as a conditioner of the effects of stressful life events on illness onset. Two groups of middle and upper level executives had comparably high degrees of stressful life events in the previous 3 years, as measured by the Holmes and Rahe Schedule of Recent Life Events. One group (n = 86) suffered high stress without falling ill, whereas the other (n = 75) reported becoming sick after their encounter with stressful life events. Illness was measured by the Wyler, Masuda, and Holmes Seriousness of Illness Survey. Discriminant function analysis, run on half of the subjects in each group and cross-validated on the remaining cases, supported the prediction that high stress/low illness executives show, by comparison with high stress/high illness executives, more hardiness, that is, have a stronger commitment to self, an attitude of vigorousness toward the environment, a sense of meaningfulness, and an internal locus of control. gested that stressful life events precipitate somatic and psychological disease. This article considers the importance of personality as a conditioner of the illness-provoking effects of stress. During the last decade, investigators have shown that the recent life histories of hospitalized persons contain significantly more frequent and serious stressful events than do histories of matched controls from the general population (e.g., Paykel, 1974) and that Navy personnel who begin a cruise with high stress scores suffer more illness episodes during the months at sea than do sailors who start out with low stress scores (Rahe, 1974). But the possibility of a causal connection between stress and illness is hardly a new idea. Physicians, philosophers, and persons simply
An exceptional number of studies in the last 20 years (cf. Dohrenwend & Dohrenwend, 1974; Gunderson & Rahe, 1974) have sugThis article is based on the author's doctoral dissertation (Kobasa, 1977), submitted to the Department of Behavioral Sciences at the University of Chicago. The preparation of this manuscript was supported in part by Public Health Service Grant MH28839-01 from the National Institute of Mental Health. The author wishes to thank Robert R. J. Hilker, James Kennedy, and all of the executives who participated in the study. Special appreciation is extended to Salvatore R. Maddi who supervised the project. Chase P. Kimball, David E. Orlinsky, and Marvin Zonis contributed many useful suggestions as dissertation committee members. Requests for reprints should be sent to Suzanne C. Kobasa, Department of Behavioral Sciences, University of Chicago, 5848 S. University Avenue, Chicago, Illinois 60637.
Copyright 1979 by the American Psychological Association, Inc. 0022-3514/79/J701-0001S00.75
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SUZANNE C. KOBASA
concerned about staying healthy have long wondered about the etiological significance of life events. The distinctiveness of recent research lies in its attempt to define and measure stress. In the current studies, a life event is denned as stressful if it causes changes in, and demands readjustment of, an average person's normal routine. This definition of stress has relied upon the empirical demonstration (Holmes & Masuda, 1974; Holmes & Rahe, 1967) that there is a general consensus about the degree to which specific life occurrences involve change and require readjustment. This consensus emerged from the ratings of stressfulness of a long list of events made by thousands of subjects varying in age, sex, socioeconomic status, race, cultural background, education, and religion. From this consensus, stressfulness weights for the life events were obtained. Deriving from this research is the Schedule of Recent Life Events (Holmes & Rahe, 1967), which contains positive (e.g., marriage), negative (e.g., illness of a family member), frequent (e.g., minor traffic violation), and rare (e.g., death of a child) occurrences. The associated Social Readjustment Rating Scale (Rahe, Lundberg, Theorell, & Bennett, 1971) gives the consensual weights for these events (e.g., on a scale from 1 to 100, divorce gets a mean score of 73 and vacation, a score of 13). The stressfulness of a particular person's life is measured in this procedure by finding out what events he or she has encountered and scoring the occurrences according to their consensually quantified weights. This consensual approach to stress as measurable environmental input has allowed easy collection of large amounts of data and uncomplicated analysis of the statistical relationship between stressful life events and illness onset. The findings of stress research have had dramatic impact in both professional journals and popular magazines. In the journals (e.g., Rabkin & Struening, 1976), one usually finds some caution urged about too quickly concluding a causal relationship between stress and illness on the basis of correlational and methodologically weak studies.
This warning is mitigated, however, by a sense of optimism that there is something to this stress and illness connection and a wish for studies that are more sophisticated in design and methods of analysis. But in the popular literature (e.g., Wolfe, 1972), final conclusions have already been drawn. Readers are provided with a self-administered stress test and told the likelihood of illness associated with each total stress score (e.g., a score above 300 means an 80% chance of getting sick). Readers whose stress scores are high are warned that if they wish to remain healthy they should avoid additional stressful encounters, even to the point of shunning such everyday necessities as driving on the Los Angeles Freeway. This advice seems inadequate, insofar as modern life can be characterized as inherently stressful (Brodsky, 1977; Toffler, 1970). A person might indeed be able to keep from getting married or taking on a new mortgage, but how can one prevent the effects of pollution and overcrowding or of being assigned to a different job when his or her company signs a new contract? Further, increasing levels of stress tend to coincide with increasing opportunities and potential resources (Kobasa, Hilker, & Maddi, Note 1). By avoiding stress, modern persons may be turning away from a chance to better their lives. Before deciding to avoid stressful life at any cost, one should consider the actual magnitude of the relationship between stress and illness. Although correlations range from .20 to .78, the majority fall below .30, and in Rahe's naval data, the correlations are consistently around .12 (Rabkin & Struening, 1976). Many stress and illness researchers, in their preoccupation with group means, have failed to question the distribution of their data. Variability of both stress and illness scores within groups has been observed to be extreme in several studies (Wershow & Reinhart, 1974). One likely explanation for these data is the presence of subjects with high stress scores who are not getting sick. Oddly, such subjects have been overlooked in the popular and professional literature on stress and illness.
STRESSFUL LIFE EVENTS
Studying Stressed but Healthy Persons
ness of authentic living, White (1959) on competence, Allport (1955) on propriate In contrast, the present study considers striving, and Fromm (1947) on the produchow highly stressed subjects who remain tive orientation. Hardy persons are considered healthy differ from those who show illness to possess three general characteristics: (a) along with high stress. Studying the individual the belief that they can control or influence who undergoes high degrees of stress without the events of their experience, (b) an ability falling ill amounts to inquiring about the to feel deeply involved in or committed to the mediating factors that affect the way one re- activities of their lives, and (c) the anticipaacts to stress. Holmes and Masuda (1974) tion of change as an exciting challenge to and the majority of other stress investigators further development. Much research has alattempt to draw a direct causal link between ready shown the advantages in behavior of the occurrence of stressful life events and the control (e.g., Lefcourt, 1973; Rodin & Langer, onset of illness by reference to the physio- 1977; Rotter, Seeman, & Liverant, 1962; logical model of a stress reaction formulated Seligman, 1975), commitment (e.g., Antonovby Hans Selye (1956). Stressful life events sky, 1974; Kobasa & Maddi, 1977; Lazarus, are said to evoke "adaptive efforts by the hu- 1966; Lazarus, Averill, & Opton, 1974; Moss, man organism that are faulty in kind or dura- 1973), and challenge (Fiske & Maddi, 1961; tion, lower 'bodily resistance' and enhance the Maddi, 1967). In discussing the hypotheses probability of disease occurrence" (Holmes presented below, the implications of theory & Masuda, 1974, p. 68). Holmes and others, and research concerning these three general however, fail to take into account what Selye characteristics are extended to considerations goes on to say about individual differences of health and illness. and the stress reaction. In the study described Hypothesis 1. Among persons under stress, in this article, the more subtle points in those who have a greater sense of control Selye's work are referred to, in the attempt over what occurs in their lives will remain to consider factors in the stress reaction that healthier than those who jeel powerless in the serve to deflect the negative impact of stress- face of external forces. Following the model ful events. Mediators of the stress and illness proposed by Averill (1973) to explain his connection, which probably include physio- laboratory observation that some organisms logical predisposition, early childhood experi- are not debilitated by stressful stimuli, the ences, and social resources, as well as the highly stressed but healthy person is hypothemediator emphasized here, personality, are to- sized to have (a) decisional control, or the gether responsible for what Selye calls the capability of autonomously choosing among distinctive way in which each individual various courses of action to handle the stress; "takes to" stressful life occurrences. (b) cognitive control, or the ability to interThe proposition of this study is that per- pret, appraise, and incorporate various sorts sons who experience high degrees of stress of stressful events into an ongoing life plan without falling ill have a personality structure and, thereby, deactivate their jarring effects; differentiating them from persons who become and (c) coping skill, or a greater repertory sick under stress. This personality difference of suitable responses to stress developed is best characterized by the term hardiness. through a characteristic motivation to achieve The conceptual source of the supposition, in across all situations. In contrast, the highly contrast to the passive and reactive view of stressed persons who become ill are powerless, humankind found in most stress and illness nihilistic, and low in motivation for achievework, is a set of approaches to human bement. When stress occurs, they are without havior that Maddi (1976), in his categorization of the major personality theories, calls recourse for its resolution, give up what little fulfillment theories. The hardy personality control they do possess, and succumb to the type formulated here builds upon the theoriz- incapacity of illness. Hypothesis 2. Among persons under stress, ing of existential psychologists (Kobasa & those who feel committed to the various areas Maddi, 1977; Maddi, 197S) on the strenuous-
SUZANNE C. KOBASA
of their lives will remain healthier than those who are alienated. Committed persons have a belief system that minimizes the perceived threat of any given stressful life event. The encounter with a stressful environment is mitigated by a sense of purpose that prevents giving up on one's social context and oneself in times of great pressure. Committed persons feel an involvement with others that serves as a generalized resistance resource against the impact of stress (Antonovsky, 1974). Committed persons have both a reason to and an ability to turn to others for assistance in times demanding readjustment. Although commitment to all areas of life— work, social institutions, interpersonal relationships, family, and self—should be characteristic of highly stressed persons who do not fall ill, one area is singled out as particularly important for health. Staying healthy under stress is critically dependent upon a strong sense of commitment to self. An ability to recognize one's distinctive values, goals, and priorities and an appreciation of one's capacity to have purpose and to make decisions support the internal balance and structure that White and other theorists (cf. Coelho, Hamburg, & Adams, 1974) deem essential for the accurate assessment of the threat posed by a particular life situation and for the competent handling of it. Hypothesis 3. Among persons under stress, those who view change as a challenge will remain healthier than those who view it as a threat. Persons who feel positively about change are catalysts in their environment and are well practiced at responding to the unexpected. Because they value a life filled with interesting experiences, change seekers have well explored their environment and know where to turn for resources to aid them in coping with stress. They have a predisposition to be cognitively flexible, which allows them to integrate and effectively appraise the threat of new situations. Their basic motivation for endurance allows them to persist even when the new information is exceedingly incongruous and, thereby, maximally provoking of strain and illness (Moss, 1973). Given the characterization of hardiness contained in the first two hypotheses, it should
be clear that the highly stressed but healthy individual is not engaging in irresponsible adventurousness. At the core of the search for novelty and challenge are fundamental life goals that have become, in adulthood, increasingly integrated in a widening diversity of situations (Henry, 1968; Neugarten, 1974). Although personality is the primary concern of the study reported here, other kinds of variables may well differentiate the highly stressed and healthy from those who have fallen ill under stress. These would include a variety of psychological, social, physiological, and environmental mediators. In order to increase understanding of those who fall ill and stay healthy under high stress, the present study included information concerning various demographic characteristics and perceptions of stressfulness of events. Method Overview The first task was the identification of high stress/ low illness and high stress/high illness groups. For this purpose, all members (# = 837) of a large subject pool were mailed a stress and illness questionnaire. They were asked to report, by month and year, which of a list of stressful life events and illness episodes they had experienced in the previous 3 years. A total stress score and a total illness score were obtained for each subject by the standard procedure of noting the items checked and multiplying these by their frequencies and consensually denned weights. Subjects were then assigned to one of the two groups or put aside. Assigned to the high stress/ low illness and high stress/high illness groups were 126 subjects above the median for total stress and below the median for total illness and 200 subjects above the median for total stress and above the median for total illness, respectively. Discarded subjects included 322 low-stress cases and 22, or all, of the female subjects. In further group refinement, 40 high stress/high illness cases whose peak illness score preceded rather than followed their peak stress score and 10 borderline cases from each of the two groups were put aside. Finally, because of a request from the company for which all of the subjects worked that the sample to be administered personality questionnaires be kept at a workable minimum, a set of 100 subjects was randomly selected from the 116 remaining high stress/low illness cases and 100 randomly selected from the 150 remaining high stress/high illness subjects. Within 3 months of the stress and illness testing, the two groups were mailed another questionnaire. This questionnaire contained several personality tests,
STRESSFUL LIFE EVENTS along with questions about demographics and perception of life stressfulness. The data from approximately half of each group were used to test hypotheses concerning group differences in hardiness. Data from the remaining cases in each group were used to cross-validate the results. The division of the groups into test and crossvalidation cases was necessitated by the statistical technique relied upon in the study, discriminant function analysis, which has been characterized in previous research by problems of generalizability due to instability of results (cf. Huberty, 1975). Although powerful as a tool for looking at group differences, discriminant function analysis, like regres sion analysis, has not always provided results that hold up in the making of inferences from sample results to some population, and over repeated samplings. Until a replication of the study is possible, the use of a "holdout sample" must be relied upon for an accurate test of the adequacy of the derived discriminant function that defines group differences.
Subjects This study required a subject pool both large and stressed enough to obtain sufficiently large groups for study. All of the middle and upper level executives of a large public utility served as the pool from which groups were selected. This utility, in the year prior to the onset of the study, had entertained serious discussion (in executive seminars, company publications, and consultations with the medical department) of the increasing numbers of stressful events faced by executives. These events consisted of changes instituted by the utility itself, like a program of job evaluations that led to some promotions and many more demotions, as well as requirements for readjustment from external sources, such as the federal government's affirmative action demands. These changes, coupled with the expected usual range of personal and family stresses, suggested that stress scores for the subject pool would be generally high. Demographically, the pool was quite homogeneous. The modal characteristics of the subjects were (a) male gender; (b) 40 to 49 years of age; (c) married, with two children; (d) on the third or middle management level, and having been there for 6 years or more; (e) possessing at least a college degree; (f) wife not working outside the home; (g) usually Protestant, and attending religious services very or fairly often.
Measurement oj Stress and Illness The most frequently used scales in stress and illness research, the Schedule of Recent Life Events and the Social Readjustment Rating Scale (Holmes & Rahe, 1967), were employed in this study. Additions to these scales were made on the basis of pilot testing. The majority of additions were more detailed specifications of the original items, modeled after suggestions from other adapters of the test (Hough, Fairbank, & Garcia, 1976; Paykel, 1974).
Each of the most ambiguous events was replaced by two events, one presenting the positive form of the Holmes and Rahe item and the other, the negative version. "Change in financial state," for example, was translated into "improvements in financial state" and "worsening of financial state." These specifications were given the seriousness weights of the items from which they were derived. Other additions to the Holmes and Rahe list were based on a pilot use of the test with SO randomly selected executives. In response to the question "What other events have you experienced during the past 3 years?", these subjects reported 15 events not found on the original list. Most of these referred to occurrences at work. Seriousness weights were assigned to these additions by the investigator and 20 other judges using the ratio scale judgment procedure of Holmes and Rahe (1967). The illness items in the stress and illness questionnaire were taken from the Wyler, Masuda, and Holmes (1968) Seriousness of Illness Survey. After consultation with the medical director of the executives' company, 118 of the diseases listed in this survey were chosen as applicable to the pool being tested. Each illness item is characterized by a seriousness weight based on a consensual agreement of numerous and diverse judges (both medical and lay) and is obtained in a manner similar to the derivation of the Social Readjustment Rating Scale. The reliability and validity of this scale as a complete listing of disease syndromes in a form accessible to both laypersons and physicians, and as an accurate set of evaluations of the general seriousness of various distinct illnesses, has been established (cf. Wyler, Masuda, & Holmes, 1970).
Measurement of Personality, Demographic, and Perception Variables A composite questionnaire, made up of all or parts of four standardized and two newly constructed instruments, was designed to test the three personality hypotheses. The standardized tests were chosen for their theoretical relevance and empirical reliability and validity. All of the instruments are appropriate for use with a sample of executives (i.e., a group of well-educated adult professionals who are relatively free of gross psychopathology). The control dimension was measured through four different instruments. What has been called decisional control or autonomy was measured through the Internal-External Locus of Control Scale (Lefcourt, 1973; Rotter, Seeman, & Liverant, 1962), and the Powerlessness versus Personal Control scale of the Alienation Test (Maddi, Kobasa, & Hoover, Note 2). The latter instrument also provided a way of measuring cognitive control (i.e., the ability to find meaning in stressful life events) in its Nihilism versus Meaningfulness scale. Coping skill (i.e., the availability of responses with which to deal with stressful life events) was measured through the Achievement scale of the Personality Research Form (Jackson, 1974; Wiggins, 1973).
SUZANNE C. KOBASA
6
The question of whether these forms of control are accompanied by a need to dominate the behavior of others was addressed through administration of the Leadership Orientation scale of the California Life Goals Evaluation Schedules (Hahn, 1966) and the Dominance scale of the Personality Research Form (Jackson, 1974). The commitment dimension was measured by the Alienation Test (Maddi et al., Note 2). Of relevance here are the alienation versus commitment scores this test yields in five areas of functioning (work, social institutions, interpersonal relationships, family, and self). The degree of consistency across a subject's different forms of involvement was also tested. This was done through the Role Consistency Test, adapted from the Gergen and Morse (1967) SelfConsistency Test to measure the compatibility among the subject's reported five most important life roles. Measurement of the orientation to challenge required the administration of several tests. The degree to which the executive sought out rather than avoided stimulation from his environment was measured through the Preference for Interesting Experiences scale of the Hahn (1966) test and the Vegetativeness versus Vigorousness scale of the Alienation Test. The executive's ability to seek challenge even in the face of potential psychological, social, and biological threat was indexed by Hahn's scale of Security Orientation. Cognitive flexibility versus cognitive rigidity was measured through the Need for Cognitive Structure scale of the Personality Research Form and the ability to persist even in the most challenging environment, through the Need for Endurance scale of the same instrument. Finally, the degree to which an orientation toward challenge was characterized by a general sense of responsibility toward life's demands was measured through the Adventurousness versus Responsibility scale of the Alienation Test. Subjects were asked about three demographic characteristics: age, job level (third, fourth, fifth, and officer), and number of years spent at current level. Executives were also asked to rate on a scale of 1 (not at all stressful) to 7 (extremely stressful) how stressful they usually think each of the following areas of life is: work, financial concerns, social/community involvements, interpersonal relationships, family, and personal or inner-life concerns.
Results Stress and Illness Scores Of the 837 executives who were contacted by mail, 670 (80%) returned completed stress and illness questionnaires. The mean stress score was 399, with a standard deviation of 162, a range from 0 to 2,239, and a median of 306. The mean illness score was 913, with a standard deviation of 1,115, a range from 0 to 6,900, and a median of 550. Comparison of these executives' scores with norms availa-
ble in the literature (Holmes & Masuda, 1974; Wyler et al., 1968, 1970) indicates that on the average, they had experienced a moderate amount of illness (comparable to the threat of life and discomfort associated with having a peptic ulcer or high blood pressure) in the previous 3 years. During this period, they had, on the average, also encountered sufficient change and demands for readjustment in their lives to constitute major life crisis (what Holmes has associated with an 80% likelihood of getting seriously ill in the near future). A Pearson product-moment correlation of .24 (p < .025) was obtained between the total stress and total illness scores. Canonical correlations were also run to determine whether a stronger relationship might be obtained. Stress scores—both the standard weighted scores and simple frequencies—for various areas of life (work, home, community, etc.) were used as the predictor, and illness scores —both weighted and frequencies—for various body systems (cardiovascular, respiratory, etc.) were used as the criterion set. Neither analysis of unweighted stress events and illnesses nor correlations of selected types of stress with selected types of illness, however, significantly strengthened the statistical relationship between stress and illness. The weak, but significant, correlation of .24 is consistent with most of the available research reports (Rabkin & Struening, 1976). Testing oj Group Differences Completed personality questionnaires were returned by 86% of trie high stress/low illness and 75% of the high stress/high illness subjects. Forty "test" subjects were randomly selected from each group for analysis of differences across personality, demographic, and perception variables, and 81 subjects were put aside for cross-validation purposes. Mean differences between the test subjects of the two groups were evaluated by t test. None of the demographic variables and only one of the perception variables yielded significant differences, whereas several of the personality variables did so. Further evaluation of group differences was achieved by a
STRESSFUL LIFE EVENTS Table 1 Differences
Between High Stress/Low Illness* and High Stress/High Illness* Executives High stress/ low illness
High stress/ high illness
M
SD
196.05 133.61 5.92 4.10 301.15 188.93 16.50 2.10 14.60 3.26 33.47 7.34
281.02 7.90 388.47 15.12 13.85 34.63
169.86 4.61 188.44 3.20 4.46 6.80
2.49** 2.03* 2.11* -1.20 .86 .73
.73 .22 — — — .43
102.35 117.24 181.67 122.04 256.02 162.76 158.47 139.02 202.15 100.21 29.22 6.42
219.15 185.77 223.73 175.09 316.10 165.24 198.72 144.33 226.95 133.93 29.50 6.44
3.36** 1.22 1.64 1.27 .94 .19
1.04 .43
155.50 21.11 13.35 269.00 15.97 34.97 3.00
216.27 22.19 14.10 337.54 14.37 32.52 3.83
1.98* .34 1.10 1.78* -.96 -.92 2.46**
.99 .35 .21 — —.
f
Variable Control Nihilism External locus of control Powerlessness Achievement Dominance Leadership Commitment Alienation from self Alienation from work Alienation from interpersonal Alienation from family Alienation from social Role consistency Challenge Vegetativeness Security Cognitive structure Adventurousness Endurance Interesting experiences Perception of personal stress
Standardized discriminant function coefficient
* value
M
SD
140.24 6.33 2.81 164.58 2.35 6.83 1.21
160.94 8.60 2.85 174.95 3.19 7.02 1.73
— — — .30
.43
Note. For all variables, the higher the number, the greater the degree of the variable observed. Superior hardiness is indicated by higher scores on achievement, role consistency, endurance, and interesting experiences, and lower scores on nihilism, external locus, powerlessness, dominance, leadership, alienation (from self, work, social institutions, interpersonal relationships, and family), vegetativeness, security, cognitive structure, and adventurousness. A subject's scores on all areas of alienation, measured by the Alienation Test, have a possible range of 0 to 1,200. Vegetativeness, nihilism, powerlessness, and adventurousness scores, also from the Alienation Test, may range from 0 to 1,500. External locus has a low of 0 and an upper limit of 23. The scales taken from the Jackson test—achievement, dominance, cognitive structure, and endurance—have a minimum value of 0 and a maximum of 20. The California Life Goals scale—leadership, security, and interesting experiences—may range from 0 to 60. Role consistency has a low of 0 and a high of 40; perception of personal stress can range from 0 to 7. a « = 40. * p < .05. ** p < .01. discriminant function analysis done on all the personality variables plus the one perception variable that yielded a significant t score. After all data are transformed into standard scores, discriminant function analysis computes a discriminant equation, or a linear combination of weighted variables that produces the greatest statistically derivable distance between the two groups. The larger the weighting or discriminant coefficient of a variable, the more powerful it is as a group discriminator. Table 1 presents all variables submitted to
discriminant function analysis and their summary statistics, including significance of difference between groups established by t test. The results demonstrate that high stress/low illness executives can be distinguished from high stress/high illness subjects. The 11 variables for which a standardized discriminant function coefficient is provided in the table combine to form a significant function, with a Wilks's Lambda of .64, significant at the .001 level, and a canonical correlation of .60. The Wilks's Lambda (see Huberty, 1975) is a measure of the original variable's discrimi-
SUZANNE C. KOBASA
nant power, before it is removed by the discriminant function. The canonical correlation is a measure of the association between the single discriminant function and the set of dummy variables that defines the two group memberships. Given the composition of this function, the general position concerning hardiness is confirmed. High stress/low illness executives are, at least in some ways, more in control, more committed, and more oriented to challenge than are high stress/ high illness executives. Looking at the variables that make the most significant contribution to the discriminant equation and that are also responsible for significant mean differences, the high stress/low illness executives are distinguished by their sense of commitment to (or lack of alienation from) self, their sense of vigorousness (as opposed to vegetativeness) about life, their sense of
meaningfulness (as opposed to nihilism), and their internal (as opposed to external) locus of control. One perception-of-stress variable joins the important personality discriminators—high stress/low illness executives find the personal sphere of their lives significantly less stressful then do the high stress/high illness subjects. Several personality variables appear to contribute to the discriminant equation even though they do not yield significant mean differences by t test. Although it is risky to interpret the discriminant coefficients of these variables, it is worth noting that the direction of mean difference is in general consistent with the hypotheses concrening hardiness as an insulation against illness. Along with their analytic function, the discriminant coefficients also serve a classificatory and validation purpose. Multiplying a
Table 2
Differences Between All High Stress/Low Illness11 and All High Stress/High Illnessb Executives
Variable Control Nihilism External locus of control Powerlessness Achievement Dominance Leadership Commitment Alienation from self Alienation from work Alienation from interpersonal Alienation from family Alienation from social Role consistency Challenge Vegetativeness Security Cognitive structure Adventurousness Endurance Interesting experiences Perception of personal stress • n = 86. *> n = 75. * p < .05. ** p < .01.
High stress/ low illness
High stress/ high illness
M
SD
M
SD
value
217.01 5.38 314.95 16.40 14.35 33.89
141.03 3.90 190.65 2.35 3.38 6.56
262.23 7.51 364.20 15.95 14.27 34.53
161.77 4.60 189.50 3.03 4.19 6.29
1.82* 2.05* 1.82* -1.02 -.13 .54
113.87 180.61 276.53 168.93 205.39 28.80
122.66 129.22 159.95 145.83 98.37 6.78
180.56 201.68 309.64 200.99 219.28 29.59
150.65 159.69 151.54 144.62 123.45 6.84
2.97** .89 1.30 1.35 .76 .71
160.04 21.52 13.16 276.88 15.01 34.29 2.72
133.34 6.83 2.77 165.58 2.95 6.31
215.26 22.63 13.75 330.84 14.53 32.80
1.82*
1.31
3.61
153.54 7.43 2.94 158.91 3.15 7.00 1.79
.95 1.26 1.78* -.96 -1.37
3.48**
STRESSFUL LIFE EVENTS
subject's scores on the discriminating variables by the associated coefficients allows one to predict the likelihood of the subject's membership in each of the groups. As a test of the classificatory power of the derived discriminant equation, its coefficients are (a) reapplied to the test subjects used to derive the equation and (b) applied to the scores of the "holdout" cases. The discriminant function presented in Table 1 shows predictive capability both internally and externally. Applying the unstandardized versions of the discriminant function coefficients to the raw scores used to derive the function, 78% of the "test" cases are correctly classified (80% of the high stress/low illness executives and 75% of the high stress/high illness subjects). This significantly correct (p < .025) classification is matched in the external cross-validation. Using the unstandardized coefficients on the raw data from the "holdout" subjects, 35 hits (77%) and 21 hits (60%) in the high stress/low illness and high stress/high illness groups, respectively, are realized (p < .05). These cross-validation results offer support for the stability and generalizibility of the results obtained through discriminant function analysis. An examination of the statistics for the entire sample (test cases plus holdouts), which are notably similar to those of the test cases in Table 1, illustrates the strength of the discriminant analysis. Table 2 presents the mean values, standard deviations, and t values for the full high stress/low illness and high stress/high illness groups. Discussion This study of persons who do not fall ill despite considerable stress suggests that personality may have something to do with staying healthy. Using the five most significant discriminators of the high stress/low illness executives (i.e., the variables that contribute to the discriminant equation and produce significant ts) one can speculate on what happens when the hardy individuals meet a stressful life event—how they evaluate the threat posed by the event and cope with it. A male executive having to deal with a job transfer will serve as an example. Whether hardy or not, the executive will anticipate and
experience the changes that the transfer will bring about—learning to cope with new subordinates and supervisors, finding a new home, helping children and wife with a new school and neighborhood, learning new job skills, and so on. The hardy executive will approach the necessary readjustments in his life with (a) a clear sense of his values, goals, and capabilities, and a belief in their importance (commitment to rather than alienation from self) and (b) a strong tendency toward active involvement with his environment (vigorousness rather than vegetativeness). Hence, the hardy executive does more than passively acquiesce to the job transfer. Rather, he throws himself actively into the new situation, utilizing his inner resources to make it his own. Another important characteristic of the hardy executive is an unshakable sense of meaningfulness and ability to evaluate the impact of a transfer in terms of a general life plan with its established priorities (meaningfulness rather than nihilism). For him, the job transfer means a change that can be transformed into a potential step in the right direction in his overarching career plan and also provide his family with a developmentally stimulating change. An internal (rather than external) locus of control allows the hardy executive to greet the transfer with the recognition that although it may have been initiated in an office above him, the actual course it takes is dependent upon how he handles it. For all these reasons, he is not just a victim of a threatening change but an active determinant of the consequences it brings about. In contrast, the executive low in hardiness will react to the transfer with less sense of personal resource, more acquiescence, more encroachments of meaninglessness, and a conviction that the change has been externally determined with no possibility of control on his part. In this context, it is understandable that the hardy executive will also tend to perceive the transfer as less personally stressful than his less hardy counterpart. The mechanism whereby stressful life events produce illness is presumably physiological. Whatever this physiological response is, the personality characteristics of hardiness may cut into it, decreasing the likelihood of
10
SUZANNE C. KOBASA
breakdown into illness. Needless to say, description of the actual nature of physiological mechanisms and their links to personality and stressful occurrences will have to wait for more sophisticated stress research. Until then, however, two alternative explanations of the present results should be considered. It could be argued that there is a spurious factor at work in the subjects' completion of questionnaires, one that determines what they say about personality, stress levels, and illness experience. Mechanic (1976) has discussed the possible distortion of stress data by a variable that he calls illness behavior. From Mechanic's perspective, one could suggest that the high stress/high illness executives have not really undergone any physiological breakdown but that they simply want to act and be treated as if they are sick and thereby withdraw from a life situation experienced as too stressful. The best evaluation of this position would come from a study that employs physiological rather than self-report measures of illness and monitors physiological states before and after the occurrence of a stressful life event. Until such studies are available, reliance must be placed on data already collected. Mechanic's explanation seems much more likely to apply to the self-report of mild, vague symptoms than to report of more serious illness. For example, headaches and indigestion might well be reported by subjects engaging in illness behavior. But it seems unlikely that definite illnesses requiring medical diagnosis, such as heart attack, cancer, detached retina, and even hypertension would be erroneously reported. Illnesses of the latter sort are responsible for high illness scores on the self-report instrument used in the present study. It is therefore not likely that the results obtained can be explained completely by the concept of illness behavior. Another alternative explanation would suggest that the observed personality differences between the high stress/low illness and the high stress/high illness executives result from the latter group having experienced illness. Presumably, the high stress/high illness executives were not more alienated, external in beliefs concerning locus of control, and uninterested in change before the illnesses occurred. Their responses to the personality
questionnaire may reflect the psychologically debilitating effects of illness. A prospective, longitudinal study in which stress and personality scores at Time 1 are used to predict illness scores at Time 2 is obviously necessary. But the present study provides some basis for regarding the alternative explanation as less likely than that offered here. Although not discussed in this report, subjects found to be low in stress and high in illness showed personality scores midway between the high stress/low illness and high stress/high illness groups (Kobasa, 1977). It is of specific relevance to the alternative explanation that the low stress/high illness subjects were lower on nihilism, alienation from self, vegetativeness, and external locus of control than were high stress/high illness subjects. This finding indicates that personality questionnaire responses indicative of lack of hardiness are not merely a response to illness. Continued work in the area of stress is essential. There is still much to be learned about the role of personality and other mediators in the connection between stressful life events and illness or health. Should studies incorporating physiological measures and employing prospective designs confirm the present findings, then instead of merely warning persons to avoid stressful lives, social scientists will be able to illuminate ways of developing the personality characteristics that can aid in a productive and healthy life led in the full complexity of modern, urbanized, industrialized societies. Reference Notes 1. Kobasa, S. C., Hilker, R. R. J., & Maddi, S. R. Remaining healthy in the encounter with stress. Paper presented at the meeting of the American Medical Association Congress on Occupational Health, St. Louis, Missouri, September 1977. 2. Maddi, S. R., Kobasa, S. C., & Hoover, M. The Alienation Test: A structured measure of a multidimensional subjective state. Manuscript submitted for publication, 1978.
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