This study extends the substantial corpus of evidence that personality plays a unique role in health outcomes by demonstrating that this effect does not occur solely within an individual, but also reflects the personality of a close partner. Most previous research examining the role of personality in health—and, in particular, the role of conscientiousness in positive health—has been based on the reasonable assumption that a person’s own personality is important for that person’s health. However, research focusing on couples and families has indicated that the personalities of people in an individual’s social networks might also play a role in that individual’s positive outcomes, including good health. And the present study, involving a large national sample, shows that having a partner who is more self-controlled, persistent, and organized facilitates better health outcomes in middle-aged and older couples.
The key personality traits we considered were conscientiousness and neuroticism. Higher levels of conscientiousness were associated with better self-rated health and fewer physical limitations. Moreover, the effect of conscientiousness was compensatory. Having a spouse who was more conscientious predicted better health and physical condition above and beyond a participant’s own conscientiousness. These results further bolster the argument that conscientiousness is a critical epidemiological factor that contributes to better health (Roberts, Walton, & Bogg, 2005
), but also raise the question of how a partner’s conscientiousness facilitates an individual’s health. Partners higher in conscientiousness might be more reliable and consistent providers of support and might be a source of more constructive advice and feedback about health-related issues. A partner’s communications about health may be solicited by the actor or may be unsolicited, and may be perceived by the actor as pleasant or interfering (J. Smith & Goodnow, 1999
). Such communications include specific reminders to take medicine, walk rather than drive, eat healthy foods, and not smoke, as well as general exchanges about appearance, weight, and the health-related habits of other people. Such forms of support from a spouse may be especially beneficial if the spouse is conscientious and one is conscientious oneself.
One question that could be raised is whether an additive or multiplicative (e.g., moderator) model is more appropriate for testing and establishing the existence of the compensatory effect of partner’s conscientiousness. The conceptual idea of compensation provides little help in choosing between these two models, as it usually implies that people make up for their own failings with other strengths (e.g., Baltes, 1997
) or that one person makes up for another person’s weaknesses (Backman & Dixon, 1992
). The appropriateness of the additive or multiplicative model rests, in part, on one’s assumptions about the appropriate level of analysis. For example, if one assumes that the individual is the appropriate unit of analysis, then the moderator model would be the correct model for testing the compensatory effect. This is the case because one would assume that no compensation is required for a person high in conscientiousness, because that person’s high conscientiousness would be sufficient. Therefore, the compensatory effect would be best demonstrated with an interaction between partner’s and participant’s conscientiousness such that low conscientiousness in an individual is compensated for by being married to someone who is highly conscientious.
Given the definitional ambiguity of the idea of compensation, however, there is no reason to assume that the person alone is the appropriate level of analysis, or that any one person’s maximum level of conscientiousness would ever be sufficient. Thus, an additive model may be just as appropriate for testing and inferring the existence of compensatory effects. Consistent with this idea is the proposal by some evolutionary theorists that humans have been subject to group-level selection pressures, in addition to individual-level selection. That is, these theorists argue that the survival of an individual’s gene line has been determined in part by the psychological makeup of the group surrounding that person’s ancestors (Wilson, Van Vugt, & O’Gorman, 2008
). Wilson et al. have argued that specific features of human personality, such as being conscientious, are the result of groups of people being more effective at dealing with selection pressures than any one person is. Consequently, no level of conscientiousness within any given person would be enough to fully account for outcomes, such as health. This perspective suggests that one could always benefit from being surrounded by supportive individuals who are high in conscientiousness. Thus, the results of the present study support the notion of an additive compensatory effect whereby extra conscientiousness located in the group is always beneficial and compensates for deficits inherent in each individual.
As in past research, neuroticism had a deleterious effect on health outcomes. People who were more neurotic rated their health lower and reported a greater number of physical limitations. The significance of these findings is bolstered by recent evidence showing that increases in neuroticism in old age are associated with increased mortality (Mroczek & Spiro, 2007
). People higher in neuroticism may experience greater stress, which has widespread ramifications for health through decreased immunity and increased difficulty handling serious health issues (T.W. Smith, 2007
The effect of neuroticism on mortality is heterogeneous, however (Roberts et al., 2007
). In some cases, higher levels of neuroticism have been associated with longevity. The synergistic relation between neuroticism and conscientiousness points to the fact that under certain circumstances, neuroticism may be beneficial. Being nervous and worried while simultaneously being more conscientious provides a context for neuroticism to have a positive effect on health. In this study, people with higher levels of both conscientiousness and neuroticism were healthier. Moreover, wives with husbands who possessed both traits were healthier still. We assume that this combination of personality traits would lead people to be more diligent about health-related issues and that, in the case of men, it would lead them to be more diligent both for themselves and for their wives. For example, men who worry about their wives might be more inclined to remind their wives to take their medications, exercise, or eat a healthier diet.
One obvious limitation of the present study is that it is cross-sectional, which makes it difficult to determine the causal direction of the associations. Numerous longitudinal studies have demonstrated the prospective effect of personality traits on health and relationship outcomes (Roberts et al., 2007
), implying that personality traits may play a causal role. For example, individuals who are more neurotic are more likely to find successive relationships less satisfying despite changing relationship partners over time (Robins, Caspi, & Moffitt, 2002
). However, theoretical models of coping with chronic illness and physical limitations, for example, suggest that the onset of a health problem can be a catalyst for the development of dyadic adjustment strategies, as well as a test of a relationship’s quality, vulnerability, and efficacy in terms of social support (e.g., Berg & Upchurch, 2007
; Stanton, Revenson, & Tennen, 2007
). Moreover, several studies have linked changes in health-related factors to changes in personality (Mroczek & Spiro, 2007
; Roberts & Bogg, 2004
; Siegler et al., 2003
). Given the range of findings, it would be prudent to assume that the relation between personality and health is reciprocal until further tests show otherwise.
To date, few large samples of older couples have been available to study questions about the social and interpersonal contexts of health within a marriage or partnership. The nationally representative HRS offers a rare opportunity to redress this gap. However, the sheer size of the sample creates several issues. For example, many of the interaction effects were quite small, though still statistically significant because of the large sample size. The meaning and importance of these small effects should be addressed in new samples, using techniques that tie the effects to a concrete outcome, such as mortality. Then, the meaning and significance of these effects would be clearer. Also, despite the large sample, there still may be questions concerning the generalizability of these results. The majority of the HRS participants are over the age of 50. Older adults are reported to be higher in conscientiousness and lower in neuroticism than younger adults (Roberts, Walton, & Viechtbauer, 2006
; Srivastava, John, Gosling, & Potter, 2003
). Furthermore, older couples have, on average, lived together longer than young couples, so the likelihood of significant compensatory and synergistic personality influences is increased among older couples. For example, older marriages are characterized by less potential for conflict, greater potential for pleasure, and higher levels of collaborative expertise in problem solving and planning (e.g., Berg & Upchurch, 2007
; Dixon & Gould, 1996
; Levenson, Carstensen, & Gottman, 1993
; J. Smith, 1996
). Therefore, the associations observed in the present study should be explored in younger cohorts.
In addition to testing these associations in alternative samples, future research could address several omissions of the present study. The measure of personality traits was relatively short, which may undermine its validity. Using more expanded models of conscientiousness and neuroticism would afford the opportunity to identify the aspects of these personality domains that are most important for health. Furthermore, although independent ratings of personality were used, alternative methods, such as observer ratings or experience-sampling measures of personality, would provide much needed confirmation of our results. Also, future research should move beyond self-reported health outcomes and assess more objective indices of physical health, such as physicians’ ratings of health, or physiological measures, such as blood pressure, body composition, and physical conditioning. Finally, many of the processes through which personality may affect health in a couples context remain untested. These effects may be the result of direct behavioral interventions or may be due to relationship norms that develop over time. These and other mechanisms should be investigated in future research.
In summary, the present research showed that conscientiousness not only directly affects health, but also has a compensatory effect on health through a partner. Furthermore, neuroticism, though typically negatively related to health, has a synergistically positive effect on health when paired with high levels of conscientiousness.