Personal Relationships, 14 (2007), 551 569. Printed in the United States of America. Copyright Ó 2007 IARR. 1350-4126=07 Stress, sex, and satisfaction in marriage GUY BODENMANN, a THOMAS LEDERMANN, a AND THOMAS N. BRADBURY b a University of Fribourg, Switzerland and b University of California, Los Angeles Abstract Using data from 198 couples, this study examines whether associations between stress occurring outside of the dyad and key indicators of relationship functioning are mediated by stress arising within the dyad. Findings suggest that relationship satisfaction and sexual activity are governed by hassles and problems experienced within the dyad that are in turn related to stress arising outside the dyad. Associations between external stress and relationship functioning are stronger for daily hassles than for critical life events. Higher levels of daily stress predicted less sexual activity for maritally dissatisfied women and more sexual activity for maritally dissatisfied men. Self-reports of stress covaried with self-reported indexes of satisfaction and sexuality, suggesting that contextual influences are broadly influential in intimate relationships. Theorists have expanded the long-standing view that interpersonal processes are a primary cause of marital outcomes, in recognition of the possibility that interpersonal processes themselves are associated reciprocally with the stressful events and chronic stressors to which couples are exposed. Drawing from earlier models highlighting the influence of minor hassles (e.g., Burr & Klein, 1994) and major life events (e.g., McCubbin & Patterson, 1983), these formulations aim to articulate how these contextual influences intersect with specific interactional processes and individual difference variables to produce changes in satisfaction and relationship stability. Karney and Bradbury s (1995; Bradbury & Karney, 2004) theoretical framework, derived from their meta-analysis of the large literature on marriage, posits that distress and dissolution Guy Bodenmann, Institute for Family Research and Counseling, University of Fribourg, Fribourg, Switzerland; Thomas Ledermann, Institute for Family Research and Counseling, University of Fribourg, Fribourg, Switzerland; Thomas N. Bradbury, Department of Psychology, University of California, Los Angeles. Correspondence should be addressed to Guy Bodenmann, University of Fribourg, Institute for Family Research and Counseling, Rue de Faucigny 2, CH-1700 Fribourg, Switzerland, e-mail: joseguy.bodenmann@unifr.ch. emerge from the combination of: (a) enduring vulnerabilities (e.g., problematic personality traits such as neuroticism, turbulent family of origin), (b) stressful events (e.g., major life events, stressful circumstances, normative transitions), and (c) poor adaptive processes (e.g., inability to empathize with and support the partner; defensive, hostile, and disengaged problem-solving skills). This perspective assumes that marital quality fluctuates downward as acute life events compromise these adaptive processes, and these fluctuations are expected to be especially large when chronic stress is high (Karney, Story, & Bradbury, 2005). Bodenmann s (2000, 2005) model further specifies the role of internal stress (e.g., negative communication patterns and dyadic conflicts, health problems of one partner) and external stress (e.g., work stress, financial stress, stress resulting from the family of origin and living in impoverished neighborhoods) in marriage. This framework assumes that chronic minor stresses, which originate outside the relationship and increase the likelihood of marital tension and conflict, are particularly deleterious for marriage because they erode relationship quality slowly and often outside of conscious awareness. This model hypothesizes that chronic external stress 551
552 G. Bodenmann, T. Ledermann, and T. N. Bradbury affects marital satisfaction via four mediating processes: (a) decreasing the time that partners spend together, which in turn results in a reduction of shared experiences, weakening feelings of togetherness, decreasing self-disclosure, and jeopardizing dyadic coping; (b) decreasing the quality of communication by eliciting less positive interaction and more negative interaction and withdrawal; (c) increasing the risk of psychological and physical problems, such as sleep disorders, sexual dysfunction, and mood disturbances; and (d) increasing the likelihood that problematic personality traits will be expressed between partners (e.g., in the form of rigidity, anxiety, and hostility). These frameworks provide the conceptual basis for the present work, which tests the premise that minor and major stresses arising outside the dyad serves as an exogenous variable that covaries with internal stressors within the dyad, which then mediates the effects of external stressors on endogenous variables, including partners global evaluations of the marriage and sexual intimacy. Brief review of research Research addressing relationship quality and sexual functioning is beginning to shed light on the interplay between stress and marital functioning. Thus, several studies show a significant association between higher levels of stress and lower levels of relationship satisfaction (e.g., Bodenmann, 2000, 2005; Cohan & Bradbury, 1997; Harper, Schaalje, & Sandberg, 2000; for a review, see Story & Bradbury, 2004); however, it seems that marital satisfaction is linked more closely to daily hassles than to critical life events (see Williams, 1995). A 5-year longitudinal study by Bodenmann and Cina (2006) extends this work by showing that daily hassles are among the most important predictors of divorce. Recent studies also begin to outline the role that distal forms of stress (e.g., poverty) play in expressions in warmth and hostility (Cutrona et al., 2003) and how different forms of stress can interact to hasten the rate at which marriages deteriorate (Karney et al., 2005). Stress is also likely to affect physical intimacy. Research links a satisfying sexual relationship, characterized by satisfaction with the quality and frequency of sex and by the absence of sexual dysfunction, with greater feelings of love (e.g., Hendrick & Hendrick, 2002), marital happiness (e.g., Brezsnyak & Whisman, 2004), and lower levels of marital conflict (Metz & Epstein, 2002). Studies also show that stress within the dyad, in the form of marital tension and conflict, covaries with lower sexual satisfaction and greater likelihood of sexual dysfunction (e.g., Hurlbert, Apt, Hurlbert, & Pierce, 2000). Surprisingly, Morokoff and Gillilland (1993) showed that desired frequency of sexual intercourse increased with daily hassles for husbands and for wives. Although we would not expect a positive association between hassles and sexual desire, it is consistent with McCarthy s (2003) view that sexual activity may often serve to reduce tension as couples contend with stressors in everyday life or marriage. Acute life events in the past 6 months, in contrast, were unrelated to sexual functioning (after controlling for age) in the Morokoff and Gillilland study, though unemployed men experienced more difficulties in sexual performance compared to employed men. Goals of the present study The accumulated evidence suggests that the ecological niche in which couples reside is associated with the level of satisfaction they experience and the quality of the communication and physical intimacy they display. At the same time, a few important shortcomings of these studies are apparent. First, most of the studies fail to differentiate between minor forms of stress, such as daily hassles (see Lazarus & Folkman, 1984) and major stress, or they assess only one of these forms of stress. Second, studies focusing on everyday stress and daily hassles often do not distinguish explicitly between stress that is internal and external to the dyad, which is likely to inflate correlations with marital processes and outcomes. Third, research examines the association between stress and marriage most often in relation to such outcomes as marital satisfaction or marital communication. Relatively few studies examine sexuality, either by itself or in
Stress, sex, and satisfaction 553 conjunction with other marital outcomes. Fourth, several of these studies assess individual spouses without corresponding data from their partners. As a result, studies have not examined dyadic effects systematically, and we know little about the reciprocal effects of the stress experienced by one partner on the marital satisfaction and sexuality of the other. The present report builds on the growing theoretical interest in stress and marriage, and the empirical literature that supports this interest, while also addressing important limitations in existing studies. Specifically, we distinguish between (a) stress that is external versus internal to the couple, (b) critical life events and daily hassles, (c) actor and partner effects, and (d) a range of different facets of marital quality, including marital satisfaction, and various indexes of sexual functioning (sexual satisfaction, activity, and dysfunction) in testing the following hypotheses. Hypothesis 1. As shown in Figure 1, we test the hypothesis that external stress predicts more hassles and higher tension within the dyad, which in turn predicts lower relationship functioning (i.e., marital satisfaction and sexual functioning). That is, we predict that experiences of internal stress within the dyad mediate, at least partially, the relationship between external stress and relationship functioning. Hypothesis 2. We predict that actor effects (i.e., the association between the stress that one person reports and his or her marital functioning) will be greater in magnitude than parallel partner effects (i.e., the association between the stress that one person reports and his or her partner s marital functioning). More importantly, based on findings suggesting that wives report more stress than husbands (e.g., Bodenmann, 2000; Cohan & Bradbury, 1997) and that wives changes in satisfaction appear to be more responsive to stress than those of husbands (e.g., Karney et al., 2005), we predict that the daily hassles and stress that wives experience within the marriage will be predicted more reliably by husbands external stress than the opposite effect. Hypothesis 3. Although external critical life events may exert negative effects on marital quality (see Karney et al., 2005; Neff & Karney, 2004), we assume that negative effects of external daily hassles on marital quality will be stronger (Bodenmann, 2005; Williams, 1995). This hypothesis is consistent with Bodenmann s contention that daily hassles are particularly pernicious because they extract a small but persisting cost on individuals and their relationship, often outside of explicit awareness. a 3w External stress women a 1w Internal daily stress women a 2w Endogenous variables women E 2w R p 1w E 1w R E1 p 2w R E2 p 1m E 1m p 2m External stress men a 1m Internal daily stress men a 2m Endogenous variables men E 2m a 3m Figure 1. Actor Partner Mediator Model with external stress as exogenous variables, internal daily stress as mediators, and relationship functioning as endogenous variables.
554 G. Bodenmann, T. Ledermann, and T. N. Bradbury Hypothesis 4. Following Morokoff and Gillilland (1993), we predict that higher levels of daily hassles will predict higher levels of sexual activity. As it is possible that satisfied and dissatisfied couples will vary in their capacity to manage the effects of daily stress on their sexual interactions, we will examine whether relationship satisfaction moderates this association. Specifically, we predict that higher levels of daily hassles will covary with higher levels of sexual activity of satisfied couples, as they are likely to possess not only the interactional skills needed to discuss and defuse daily stress but also the propensity to engage in sexual activity when the daily hassles in their lives subside, however temporarily. Among dissatisfied couples, in contrast, we predict that the association between daily hassles and sexual activity will be weaker or possibly in the opposite direction as daily stress will not be negotiated as well and sexual interaction will become less likely. Method Participants Three hundred ninety-six individuals residing in the German-speaking part of Switzerland participated in the study, representing a convenience sample of 198 intact heterosexual couples. Among the women, 21% were 20 30 years, 54% were 31 40 years, and 25% were 41 years or older. Among the men, 14% were 20 30 years, 48% were 31 40 years, and 38% were 41 or older. Although a few participants ended their formal education with elementary school (10% of the women, 7% of the men), most earned a terminal high school degree (48% women, 47% of the men) or a college or university degree (42% women, 46% men). Average relationship duration was 12.4 years (SD ¼ 7.5; range ¼ 1.1 36.5 years), 75% of the couples (n ¼ 148) were married, and 70.4% had children (M ¼ 1.6; SD ¼ 1.29; range ¼ 1 5). It is important to recognize that a significant minority of the couples were not married. Comparison of married couples with not-married couples showed that unmarried participants were younger, women M ¼ 33.1 (SD ¼ 16.3) versus M ¼ 37.1 (SD ¼ 16.8), t(68) ¼ 2.39, p,.05; men M ¼ 35.8 (SD ¼ 17.1) versus M ¼ 39.4 (SD ¼ 17.9), t(77) ¼ 2.51, p,.05; and reported a shorter relationship duration, M ¼ 6.58 (SD ¼ 5.41) versus M ¼ 14.09 (SD ¼ 7.25), t(101) ¼ 7.50, p,.001. Nonetheless, married and unmarried participants did not significantly differ on any of the variables of interest, with the exception of sexual activity (assessed with five items rated on 5-point scales: 1 ¼ never; 5¼ very often; see below), where unmarried participants of both genders reported a higher frequency: women M ¼ 18.1 (SD ¼ 3.5) versus M ¼ 16.5 (SD ¼ 3.9), t(91) ¼ 2.47, p,.05; men t(86) ¼ 3.13, p,.01. Procedure and measures As insufficient resources were available to conduct a random-digit telephone survey of couples, couples instead volunteered to participate in response to community-wide newspaper advertisements placed in the German-speaking region of Switzerland. Couples contacting the laboratory about the study were mailed a packet of questionnaires that included separate and distinct materials for each partner, together with instructions to complete the questionnaires independently and to return the forms to the institute within 2 weeks. We did not pay couples for their participation as it is unusual in Switzerland to pay participants for their participation in this kind of research. In addition to providing demographic information (age, sex, education, marital status, relationship duration, relationship satisfaction, type of residence, number of children, occupation, and employment status), participants completed the following measures. Hassles Scale. We administered a shortened and adapted version of the original Hassles Scale (Kanner, Coyne, Schaefer, & Lazarus, 1981), consisting of 37 of the original 117 items. We rephrased terms that seemed redundant (e.g., we relabeled hassles associated with planning meals and caring for pet as hassles with task sharing in household ; we relabeled hassles over smoking too much and use of alcohol as hassles with unhealthy behaviors ). Participants rated all items on
Stress, sex, and satisfaction 555 5-point scales (1 ¼ not at all stressful,5¼ very stressful). The items reflected a range of daily hassles (i.e., irritating, frustrating, or distressing demands in everyday transactions) that participants rated with reference to the previous month. Factor analysis of these responses yielded one factor representing stress external to the dyad (29 items, e.g., troublesome neighbors, social obligations, financial problems, problems getting along with fellow workers, customers or clients giving you a hard time, not liking current work duties, too many interruptions, having to wait, too many things to do; internal consistency as measured by Cronbach s a ¼.86) and a second representing stress internal to the dyad (8 items, e.g., problems with your partner, overload with family responsibilities, time pressures in the family, demands of task sharing in household, different goals, annoying habits of the partner; Cronbach s a ¼.75). The mean score for external daily stress was 53.7 (SD ¼ 12.1, range ¼ 30 110) for women and 50.5 (SD ¼ 11.7, range ¼ 29 93) for men, t(188) ¼ 2.80, p,.01. Mean scores of internal daily stress were 16.1 (SD ¼ 5.0, range ¼ 8 39) for women and 14.4 (SD ¼ 4.3, range ¼ 8 28) for men, t(188) ¼ 4.59, p,.001. Life Events Questionnaire. The Life Events Questionnaire (Bodenmann, 2000), based upon the Social Readjustment Scale of Holmes and Rahe (1967) and the Life Experiences Survey by Sarason, Johnson, and Siegel (1978), assesses 27 potentially stressful life events in different domains such as personal injuries (severe illness, handicap), experiences of loss (death of a loved one), work-related events (unemployment, loss of work), and social conflicts (severe marital distress, severe social tensions with relatives, friends, neighbors or colleagues at work) within the past 12 months. Participants indicated the degree of stress caused by these life events on a 3-point scale (1 ¼ somewhat stressful, 2¼ stressful, 3¼ very stressful). The total score of the scale used in this study was the combined measure of the occurrence of critical life events multiplied by their stress impact (Cronbach s a ¼.67). In this version, we included only external major stressors (i.e., unemployment, death of a friend, changing place of domicile) that did not involve the marriage directly in order to avoid redundancy between the independent and dependent variables studied here. Prior longitudinal studies with married couples have shown that measures of this type can yield valid data (e.g., Cohan & Bradbury, 1997; Neff & Karney, 2004). The mean scores of this combined scale were 10.0 (SD ¼ 6.4, range ¼ 1 29) for women and 7.9 (SD ¼ 5.4, range ¼ 1 35) for men, t(182) ¼ 4.34, p,.001. Partnership Questionnaire. The Partnership Questionnaire (Partnerschaftsfragebogen, or PFB; Hahlweg, 1996), a 31-item measure of marital satisfaction, consists of three subscales: quarrelling (item examples: my partner blames me for things that I have done in the past; my partner criticizes me in a sarcastic way; my partner shouts at me during arguments; a ¼.91), affection (item examples: my partner makes me feel that I am physically attractive for him or her; my partner is affectionate toward me; a ¼.90), and togetherness (item examples: my partner shares his/her thoughts and feelings with me; my partner tells me what he or she had experienced during the day; a ¼.84). Items are rated on a 4-point scale with 0 ¼ never and 3 ¼ very often. In this study, we used only the affection and togetherness scales in forming an index of marital satisfaction (a ¼.93). Due to medium correlations between quarrelling and internal daily stress (r ¼.41 for women, r ¼.48 for men), we excluded the subscale quarrelling in order to avoid redundancy with internal daily stress. In this study, men reported an average score of 61.6 on the PFB and women of 61.3, t(189) ¼ 0.32, ns, indicating nondistressed couples, with considerable variation (for men, SD ¼ 15.4; range: 15 90; for women, SD ¼ 15, range: 10 90). satisfaction subscale of the Marital Satisfaction Inventory. The Marital Satisfaction Inventory (Snyder, 1981; German translation by Klann, Hahlweg, & Hank, 1992) is a 150-item true false self-report questionnaire designed to assess the nature and extent of marital distress along 11 key dimensions (e.g., effective communication, marital aggression, sexual dissatisfaction, agreement on finances,
556 G. Bodenmann, T. Ledermann, and T. N. Bradbury and conflict over child rearing). In this study, we used only the 19-item scale measuring sexual dissatisfaction, examples, my partner sometimes shows too little enthusiasm for sex; my partner has too little regard sometimes for my sexual satisfaction: women, M ¼ 8.2, SD ¼ 3.0, range ¼ 0 12; men, M ¼ 7.7, SD ¼ 3.3, range ¼ 0 12; t(187) ¼ 2.69, p,.01.werecodedthisscalesothat higher scores indicated higher satisfaction. The internal consistency of the scale was.82. Activity Scale. Designed for this study, this scale assesses the typical frequency of sexual behaviors with five items administered on a 5-point scale (1 ¼ never,2¼rarely, 3 ¼ from time to time,4¼frequently,5¼very often). Behaviors assessed include petting, partner stimulation (massages), oral sex, and sexual intercourse. The internal consistency of the scale was a ¼.86. The mean score was 17.0 (SD ¼ 3.81, range ¼ 7 25) for women and 16.4 (SD ¼ 3.75, range ¼ 5 25) for men, t(187) ¼ 2.83, p,.01. Dysfunction Scale. Following the diagnostic categories of Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM IV; American Psychiatric Association, 1994), men and women rated several potential sexual problems, indicating (a) how often they experienced these problems in the relationship (5-point scale: never, rarely, from time to time, often, very often) and (b) how much pain these problems caused (4-point scale: no pain, moderate pain, high pain, very high pain). Women rated sexual desire problems (hypoactive sexual desire), sexual aversion problems, sexual arousal problems, orgasmic problems, dyspareunia, and vaginismus; men rated sexual desire problems (hypoactive sexual desire), sexual aversion problems, erectile problems, orgasmic problems, premature ejaculation, and sexual pain problems. In this study, we used a combined measure encompassing the frequency of the sexual problems and the selfperceived pain. Cronbach s alpha of this variable was less than optimal (.68 for women and.60 for men), suggesting that these dysfunctions do not represent a common underlying construct. The average score on the combined measure was 22.6 (SD ¼ 13.7, range ¼ 6 73) for women and 14.0 (SD ¼ 9.2, range ¼ 2 77) for men, t(181) ¼ 7.16, p,.001. Symptom Check List. Derogatis (1992) developed Symptom Check List (SCL 90 R), a 90-item instrument to assess a broad range of psychological problems and symptoms of psychopathology. This instrument permits evaluation of a variety of concepts, including somatization, obsessive compulsive problems, interpersonal sensitivity, depression, anxiety and hostility. Users can employ three global scores in research as well as clinical practice. In this study, we used the global severity index to control for a general bias in the perception of the participants with regard to neuroticism. Participants rated this on a 5-point scale (0 ¼ not at all, 4 ¼ extremely). The reliability of this scale was a ¼.96. The mean score was 49.8 (SD ¼ 40.4, range ¼ 0 233) for women and 30.0 (SD ¼ 25.6, range ¼ 0 145) for men, t(189) ¼ 6.47, p,.001. Results Bivariate correlations among measures Intercorrelations among the study variables are shown in Table 1. Several associations are noteworthy. First, relationship satisfaction, sexual satisfaction, and sexual activity intercorrelate reliably. Second, sexual dysfunction appears to be a distinct variable, with low levels of association with other sexual functioning variables and a nonsignificant association between partners. Third, factor analysis of the hassles measure produced distinguishable indexes of hassles that are internal and external to the dyad. These two variables correlate among men and among women, as we would expect (rs ¼.60 and.63, respectively), yet the between-partner correlations are higher for internal hassles (r ¼.46) than for external hassles (r ¼.11), thus helping to validate the distinction we are drawing between them. Fourth, acute life events covary reliably with the external stress measure, yet these measures share less than 20% of their variance, suggesting that these are not redundant measures. Fifth, higher levels of marital satisfaction do
Stress, sex, and satisfaction 557 Table 1. Intercorrelations among study variables, for women (above diagonal) and men (below diagonal) and dyads (along the diagonal) Variables 1 2 3 4 5 6 7 8 9 10 1. Marital satisfaction.64***.56***.74*** 2.15* 2.45*** 2.23*** 2.13* 2.29*** 2.25*** 2.26*** 2. satisfaction.68***.64***.63*** 2.44*** 2.49*** 2.28*** 2.20** 2.37*** 2.14* 2.08 3. activity.73***.63***.65*** 2.27*** 2.45*** 2.24*** 2.03 2.35*** 2.17** 2.20** 4. dysfunctions 2.12* 2.22** 2.10.03.43***.33***.17*.41*** 2.17** 2.15* 5. Internal daily stress 2.35*** 2.45*** 2.27***.27***.46***.63***.44***.65***.07.02 6. External daily stress 2.07 2.23*** 2.04.19**.60***.11.34***.61*** 2.01.03 7. Critical life events 2.15* 2.23*** 2.16*.29***.36***.36***.39***.30*** 2.02 2.16* 8. SCL 90 R total score 2.21** 2.30*** 2.14*.42***.48***.48***.30***.25***.07.00 9. Age 2.22** 2.09 2.14*.09.09.00 2.11.00.73***.63*** 10. Duration of relationship 2.31*** 2.13* 2.22**.01.06 2.06 2.11 2.07.62*** 1.00*** Note. SCL 90 R ¼ Symptom Check List. N ¼ 198 men and 198 women. We present correlations between the dyad members in bold along the diagonal. *p,.05. **p,.01. ***p,.001 (one tailed). covary with lower levels of internal daily stress (r ¼ 2.35 for men; r ¼ 2.45 for women). This does suggest a modest degree of confounding between these measures. In sum, the study variables are generally performing as expected and further multivariate analyses are warranted. As relationship duration was not highly correlated with any dependent variable, we did not control for it. It is, however, conceivable that personal vulnerability creates a general bias with regard to participants ratings of stress as well as their evaluation of marital functioning. Intercorrelations among the study variables and the SCL 90 R total score ranged between j.29j (marital satisfaction) and j.65j (internal daily stress) in women and between j.14j (sexual activity) and j.48j (external and internal daily stress) in men. To control for this effect, we partialled out overall psychological distress (SCL 90 R total score) from all self-report data. Statistical analyses: Investigating mediation with dyadic data We tested hypotheses using the Actor Partner Mediator Model (see Campbell, Simpson, Kashy, & Fletcher, 2001; Fletcher & Thomas, 2000; Ledermann & Bodenmann, 2006), which allows for the analysis of mediator effects in studies using dyadic data. This model is an extended version of the widely used Actor Partner Interdependence Model (APIM) proposed by Kenny and colleagues (e.g., Kenny, 1996; Kenny & Cook, 1999), which takes into account the interdependence of data collected from dyadic partners. The classic APIM yields an estimation of the effect of one s own independent variable on one s own dependent variable (actor effect) and on the partner s dependent variable (partner effect). Using manifest variables, the APIM is a saturated model with 0 df. TheActor Partner Mediator Model outlined in Figure 1 consists of six pairwise variables (three per partner), including two manifest exogenous (independent) variables, two manifest mediator variables, and two manifest endogenous (dependent) variables. The path models used in this study with direct actor effects (horizontal
558 G. Bodenmann, T. Ledermann, and T. N. Bradbury arrows) between the exogenous and endogenous variables have 2 df; we can assume that direct partner effects (diagonal arrows) between exogenous and endogenous variables are statistically irrelevant. If the path models with 2 df fit the data well, then this assumption is verified. The assumption of complete mediation is assuming good model fit supported if the direct effects between external stress and the marital variables are not significant. Partial mediation can be inferred in the association between the exogenous and endogeneous variables if one or both of these direct effects are significant. We used the z statistic to evaluate the mediation effects between the exogenous and endogenous variables, with z ¼ ^a^b ^r^a^b ð1þ where ^a^b denotes the estimated indirect effect between X (exogenous variable) and Y (endogenous variable) through M (mediator), and ^r^a^b represents the estimated standard error of the indirect effect. The standard error will be estimated by Sobel s (1982) approximate formula that MacKinnon and his colleagues (MacKinnon, Lockwood, Hoffman, West, & Sheets, 2002; MacKinnon, Warsi, & Dwyer, 1995) recommend: ^r^a^b ¼ rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ^a 2 ^r 2^b 1 ^b 2 ^r 2^a ð2þ where ^a and ^b denote the estimated structural coefficients of the path X / M, and M / Y, respectively, ^r 2^a and ^r2^b are the estimated variances of ^a and ^b. The hypothesis holds that internal daily stress mediates the relation between exogenous variables (represented here as external stress) and endogenous variables (represented by marital functioning variables) when (a) the models show an adequate fit, (b) the direct effects constituting a mediation effect are significant, and (c) the mediation effect is significant using Equations 1 and 2. When the direct actor effects between external stress (exogenous variable) and marital functioning variables (endogenous variables) are not significant, however, the relationship between the exogenous and endogenous variables is completely mediated by internal stress. We tested differences between parameters (e.g., actor vs. partner effects) within one model by means of model comparisons comparing the default model with a nested model assuming equal parameters. We will assume that parameters are statistically different when the chi-square difference test is significant. We tested differences between coefficients across different models by computing the 95% confidence limits using Fisher s Z transformation. We can say that a substantial difference exists if the confidence interval of one effect excludes the coefficient of another effect. Actor Partner Models with external daily stress as exogenous variables The estimated maximum likelihood coefficients of the Actor Partner Mediator Models with external daily stress as exogenous variables and internal daily stress as the mediator are shown in Table 2. To evaluate the fit of a particular structural model, we use chisquare, the comparative fit index (CFI), root mean square error of approximation (RMSEA), and the fit criteria proposed by Hu and Bentler (1999), who suggest a cutoff..95 for CFI and,.06 for RMSEA. According to Browne and Cudeck (1993), RMSEA values,.08 indicate an acceptable fit, and values,.05 indicate a good fit. As readers can see in Table 2 (bottom), all models with daily stress fit the data well. These findings, which indicate that the relations between external daily stress and marital functioning are at least partially mediated by internal daily stress, are consistent with Hypothesis 1. Association between external daily stress and internal daily stress. As shown at the top left side of Table 2, actor effects relating external daily stress and internal daily stress were statistically significant, for women and for men. As partner effects were not significant and as women s actor effect were significantly higher than the partner effect from men to women (v 2 Diff ¼ 9:45, p ¼.002), we found that actor effects were more important than the
Stress, sex, and satisfaction 559 Table 2. Actor and partner effects (maximum likelihood estimates), correlations, and model fits for the Actor Partner Mediator Model with internal daily stress as mediator and the overall distress (Symptom Check List [SCL 90 R]) as covariables Models with external daily stress Models with acute life events Source Marital satisfaction satisfaction activity dysfunction Marital satisfaction satisfaction activity dysfunction External stress / internal daily stress Actor effects Women, a1w.38***.38***.38***.38***.25***.25***.25***.25*** Men, a1m.49***.49***.49***.49***.29***.29***.29***.29*** Partner effects Men / women, p1w.10.10.10.10.23***.23***.23***.23*** Women / men, p1m.00.00.00.00 2.08 2.08 2.08 2.08 Internal daily stress / endogenous variable Actor effects Women, a2w 2.31*** 2.33*** 2.27***.19** 2.29*** 2.31*** 2.25***.20** Men, a2m 2.33*** 2.35*** 2.25***.14* 2.22*** 2.33*** 2.18**.11 Partner effects Men / women, p2w 2.23*** 2.13* 2.20**.12 2.24*** 2.13* 2.21**.12 Women / men, p2m 2.26*** 2.23*** 2.22** 2.04 2.27*** 2.23*** 2.23** 2.03 External stress / endogenous variable Actor effects Women, a3w.05.04.06.03 Fixed at 0 Fixed at 0 Fixed at 0 Fixed at 0 Men, a 3m.20**.04.15* 2.08 Fixed at 0 Fixed at 0 Fixed at 0 Fixed at 0 Correlations Between exogenous variables, R.01.02.01.02.34***.34***.34***.34*** Between error terms 1, RE1.31***.31***.31***.31***.27***.27***.27***.27*** Between error terms 2, R E2.52***.55***.60*** Fixed at 0.52***.55***.60*** Fixed at 0 Explained variances R 2 w internal daily stress women (%) 16 16 16 16 16 16 16 16 R 2 m internal daily stress men (%) 24 24 24 24 8 8 8 8 R 2 w endogenous variable women (%) 19 14 14 7 18 14 14 7 (continued)
560 G. Bodenmann, T. Ledermann, and T. N. Bradbury Table 2. (continued) Models with external daily stress Models with acute life events dysfunction activity satisfaction Marital satisfaction dysfunction activity satisfaction Marital satisfaction Source R 2 m endogenous variable men (%) 19 21 12 1 16 21 11 1 v 2 0.144 2.035 0.536 1.656 5.169 11.004 8.969 8.511 df 2 2 2 3 4 4 4 5 p 930.362.765.647.270.027.062.130 Comparative fit index 1.000 1.000 1.000 1.000.994.967.975.958 Root mean square error of approximation.000.009.000.000.039.094.079.060 Note. Due to a poor model fit, the estimates of the model with critical life events and sexual satisfaction cannot be interpreted. The SCL 90 R total score was partialed out from all manifest variables. *p,.05. **p,.01. ***p,.001 (one tailed). corresponding partner effects. This suggests that internal daily stress may be affected more by one s own external daily stress than by the partner s external daily stress. Association between internal daily stress and relationship functioning. Actor effects were consistent in demonstrating that higher levels of internal daily stress covaried with lower levels of marital satisfaction, sexual satisfaction, and sexual activity, and with higher levels of sexual dysfunction, for men and for women. With the exception of the sexual dysfunction variable, we found significant partner effects between internal daily stress and relationship functioning. Specifically, to the extent that one spouse reported more daily stress and tension in the relationship, the partner was more likely to report lower levels of marital satisfaction, sexual satisfaction, and sexual activity. As a group, these findings are in line with our first hypothesis that daily stress and tension within the dyad, as reported both by one s self and the partner, covary with poorer relationship functioning. Association between external daily stress and relationship functioning. With respect to direct actor effects between external daily stress and indexes of relationship functioning variables, we found no significant associations for women, but two significant associations involving marital satisfaction and sexual activity for men. These direct associations were positive, indicating that men who reported higher levels of external daily stress also reported higher levels of marital satisfaction and sexual activity. This finding has to be considered in the context of the mediator model analyses because the correlations between external daily stress and the two outcome variables sexual activity and marital satisfaction are negative (see Table 1). Among men, these positive direct effects are substantially lower than the effects between external daily stress and internal daily stress and between internal daily stress and the two outcome variables marital satisfaction and sexual activity (see Table 2). It is noteworthy that these effects may not be separate and distinct as the bivariate correlation between
Stress, sex, and satisfaction 561 marital satisfaction and sexual activity is.74 for women and.73 for men (see Table 1). Tests of mediation. To evaluate mediation effects, Equations 1 and 2 were used to test for significance. In the Actor Partner Mediator Model tested here, we can distinguish eight indirect effects (two actor actor, two actor partner, two partner actor, and two partner partner). In Table 3 we present the estimated indirect effects, standard errors, and the results of the z statistics for the mediation effects consisting of two significant direct effects. In all four models with external daily stress as exogenous variables, both indirect effects involving two actor effects were significant. There was one exception, however: In the model with sexual dysfunction, we found no significant actor actor effect for men, which was mainly due to a weak actor effect from internal daily stress to sexual dysfunctions in men. Apart from the model with sexual dysfunction, both actor partner indirect effects were substantial. The other four mediator effects including partner effects between external and internal daily stress were not significant in all four models with external daily stress as exogenous variables. Consistent with Hypothesis 1, these findings suggest that couples experiencing higher levels of external daily stress also experience higher levels of stress and tension within the dyad and, in turn, lower levels of relationship and sexual satisfaction, sexual activity, and (to a moderate extent) more sexual dysfunctions. With respect to the distinction between partial and complete mediation, the findings suggest that the relations between external daily stress and sexual satisfaction and between external daily stress and sexual dysfunction are completely mediated, whereas the associations between external daily stress and marital satisfaction and sexual activity are partially mediated by internal daily stress due to substantial direct actor effects between the exogenous and endogenous variables in men. Actor Partner Models with acute life events as exogenous variables The analyses just described were repeated using acute life events as the exogenous variables, to test the prediction that acute life events are less consequential than daily hassles in predicting daily stress within the relationship (Hypothesis 3). The first model analyses reveal poor fits for all models with direct paths between the exogenous and endogenous variables (RMSEA ranged between.081 and.132), except for the model with sexual dysfunctions as endogenous variables, v 2 (3) ¼ 2.06, p ¼.561; CFI ¼ 1.000, RMSEA ¼.000. Because the two direct effects between the exogenous and endogenous variables were small in all four models, they were excluded. The model without direct effects between the exogenous and endogenous variables counts 4 df and assumes that the relations between acute life events and the marital outcome variables are completely mediated by internal daily stress. Poor fits were obtained for the model that included sexual satisfaction and thus we do not discuss this model further. In contrast, we obtained good fits for the models that included marital satisfaction and sexual activity with respect to RMSEA an acceptable fit resulted for the model that included sexual dysfunction (see Table 2, bottom). Association between acute life events and internal daily stress. As shown in Table 2, in the remaining three models, all actor effects were substantially weaker than corresponding effects between external daily stress and internal daily stress (.25 vs..38 for women and.29 vs..49 for men; see Table 2). Given the 95% confidence limits of the actor effects between external and internal daily stress (.27 and.55 for women, and.40 and.68 for men), the effects between critical life events and internal daily stress were significantly lower than those obtained between external daily stress and internal daily stress. (This was also true for men but not for women when using the 95% confidence limit of the coefficients between critical events and internal daily stress, which were.12 and.40 for women and.16 and.44 for men.) Partner effects were also apparent, though only in the case of acute life events reported by men and internal daily stress reported by women. The confidence limits of.10 and.38 for the effect from men to women and 2.22 and.06 for the effect from women to men support Hypothesis 2: The association between
562 G. Bodenmann, T. Ledermann, and T. N. Bradbury Table 3. Mediation effects for the Actor Partner Mediator Models (APMeM) with external stress as exogenous variables, internal daily stress as mediators, and marital functioning as endogenous variables Effect IE SE z p (two tailed) 95% confidence interval APMeM with external daily stress and marital satisfaction X w / M w / Y w ¼ A / A 20.200 0.058 23.465.001 20.31 to 20.09 X w / M w / Y m ¼ A / P 20.167 0.053 23.161.002 20.27 to 20.06 X m / M m / Y w ¼ A / P 20.174 0.057 23.065.002 20.29 to 20.06 X m / M m / Y m ¼ A / A 20.242 0.065 23.737.000 20.37 to 20.12 APMeM with external daily stress and sexual satisfaction X w / M w / Y w ¼ A / A 21.061 0.302 23.512.000 21.65 to 20.47 X w / M w / Y m ¼ A / P 20.867 0.298 22.911.004 21.45 to 20.28 X m / M m / Y w ¼ A / P 20.485 0.275 21.763.078 21.02 to 0.05 X m / M m / Y m ¼ A / A 21.497 0.378 23.960.000 22.24 to 20.76 APMeM with external daily stress and sexual activity X w / M w / Y w ¼ A / A 21.152 0.371 23.109.002 21.88 to 20.43 X w / M w / Y m ¼ A / P 20.964 0.363 22.657.008 21.68 to 20.25 X m / M m / Y w ¼ A / P 20.984 0.372 22.648.008 21.71 to 20.26 X m / M m / Y m ¼ A / A 21.274 0.430 22.960.003 22.12 to 20.43 APMeM with external daily stress and sexual dysfunction X w / M w / Y w ¼ A / A 2.707 1.238 2.187.029 0.28 to 5.13 X w / M w / Y m ¼ A / P 20.358 0.790 20.453.651 21.91 to 1.19 X m / M m / Y w ¼ A / P 1.965 1.282 1.532.125 20.55 to 4.48 X m / M m / Y m ¼ A / A 1.649 1.014 1.625.104 20.34 to 3.64 APMeM with critical life events and marital satisfaction X w / M w / Y w ¼ A / A 20.007 0.002 22.743.006 20.01 to 0.00 X w / M w / Y m ¼ A / P 20.006 0.002 22.602.009 20.01 to 0.00 X m / M w / Y w ¼ P / A 20.007 0.003 22.537.011 20.01 to 0.00 X m / M w / Y m ¼ P / P 20.007 0.003 22.424.015 20.01 to 0.00 X m / M m / Y w ¼ A / P 20.007 0.003 22.550.011 20.01 to 0.00 X m / M m / Y m ¼ A / A 20.007 0.003 22.425.015 20.01 to 0.00 APMeM with critical life events and sexual activity X w / M w / Y w ¼ A / A 20.038 0.015 22.506.012 20.07 to 20.01 X w / M w / Y m ¼ A / P 20.036 0.016 22.301.021 20.07 to 20.01 X m / M w / Y w ¼ P / A 20.040 0.017 22.330.020 20.07 to 20.01 X m / M w / Y m ¼ P / P 20.038 0.017 22.163.031 20.07 to 0.00 X m / M m / Y w ¼ A / P 20.042 0.018 22.326.020 20.08 to 20.01 X m / M m / Y m ¼ A / A 20.037 0.018 22.059.040 20.07 to 0.00 APMeM with critical life events and sexual dysfunctions X w / M w / Y w ¼ A / A 0.103 0.048 2.150.032 0.01 to 0.20 X m / M w / Y w ¼ P / A 0.109 0.053 2.038.042 0.00 to 0.21 Note. In this table, we present mediation effects only for those models in which both direct effects were significant. IE ¼ indirect effect; w ¼ women; m ¼ men; A ¼ actor effect; P ¼ partner effect. Equation 1 was used to compute z scores; standard error was estimated by means of Equation 2. The formula used to compute normal 95% confidence interval is ^c^b61:96 ^r^c^b.
Stress, sex, and satisfaction 563 women s internal daily stress and men s acute life events is stronger than the association between men s internal daily stress and women s acute life events. As noted, Hypothesis 3 predicts that external daily hassles would account for more variation in internal daily stress than would acute life events. Partially consistent with this prediction, the results summarized in Table 2 show that external daily stress accounted for 16% of the variation in women s internal daily stress and 24% of the variation in men s internal daily stress; corresponding figures for acute life events were 16% and 8%, respectively. Given that partners are more similar in their reports of acute life events (r ¼.39) than their reports of external daily hassles (r ¼.11; see Table 1), this pattern of results is consistent with the notion that acute life events are more likely to be shared experiences and hence are more likely to be recognized mutually, producing less turmoil within the dyad in turn. Daily external hassles, in contrast, are more likely to be unshared experiences that are managed at the individual level and thus may evoke greater tension in the partners. Association between internal daily stress and relationship functioning. Actor effects relating internal daily stress to marital satisfaction, sexual activity, and sexual dysfunction were comparable in magnitude to corresponding effects found in the models with external daily stress except the associations between men s internal stress and men s marital satisfaction andsexualactivitythatappearedtobeweaker in the model with acute life events than the parallel associations obtained in the model with external daily stress (2.22 vs. 2.33, and 2.18 vs. 2.25). Partner effects relating internal daily stress to marital satisfaction were also evident for men and for women. The differences in the magnitude of the effects in the models with external daily stress and the models with critical events derived from the different model specification (one with direct actor effects between external stress and marital functioning having 2 df, the other without direct actor effects between the exogenous and endogenous variables having 4 df) and the substantial direct actor effects between external daily stress and marital satisfaction and between external daily stress and sexual activity in men. As in the first set of analyses, there were no partner effects relating internal daily stress to sexual dysfunction, for men or for women. Tests of mediation. As above, Equations 1 and 2 were used to test mediation effects. In all three models, both actor actor mediation effects were significant, with the exception of the model with acute events, where only women s actor actor indirect effects were substantial (Table 3). In the model with marital satisfaction and sexual activity, six of the eight mediation effects were significant. Nonsignificant mediation effects involved the effect from women s life events to men s internal stress. In the model with sexual dysfunction, only the association between men s critical events and men s sexual dysfunction via women s internal stress was significant. Marital satisfaction as a moderator of the association between daily external hassles and sexual activity. In an effort to build upon Morokoff and Gillilland s (1993) finding that daily hassles and sexual activity would covary positively, in Hypothesis 4 we predicted that this association would be moderated by marital satisfaction. We tested the Actor Partner Moderator Model (Campbell, Simpson, Kashy, & Rholes, 2001; Ledermann & Bodenmann, 2006) in which men s and women s sexual activity were predicted by marital satisfaction and external hassles of both partners, together with the interaction between satisfaction and hassles for each partner. To avoid multicollinearity, the predictors (external daily stress) and moderators (marital satisfaction) were centered as recommended by Aiken and West (1991) among others. This Actor Partner Moderator Model fit the data well (v 2 ¼ 13.06, df ¼ 9, p,.16; CFI ¼.991, RMSEA ¼.048). Significant actor and partner effects were obtained for women s marital satisfaction (.50, p,.001;.28, p,.001, respectively) and for men s marital satisfaction (.56, p,.001;.33, p,.001, respectively). Most importantly, the actor effects relating the interaction of daily hassles and marital satisfaction to sexual activity were significant for women (.10, p,.05) and for men
564 G. Bodenmann, T. Ledermann, and T. N. Bradbury (2.13, p,.01); corresponding partner effects were nonsignificant. Following Cohen, Cohen, West, and Aiken (2003), Figure 2 presents these interactions by showing the associations between daily hassles and sexual activity for individuals 1 SD above the mean, at the mean, and 1 SD below the mean in marital satisfaction. The figures for women (top) and for men (bottom) show that the moderating effects of satisfaction on the association between daily hassles and sexual activity take different forms for women and for men. Among the most satisfied women, sexual activity does not appear to vary much as a function of daily hassles. In contrast, among women who are at or 1 SD below the 25.0 Wife's sexual activity 20.0 15.0 10.0 5.0 0.0-2 2 Wife's external stress centered low marital satisfaction high marital satisfaction medium marital satisfaction 25.0 Husband's sexual activity 20.0 15.0 10.0 5.0 0.0-2 2 Husband's external stress centered low marital satisfaction high marital satisfaction medium marital satisfaction Figure 2. Association between external daily stress and sexual activity as moderated by level of marital satisfaction, for women (top) and for men (bottom). Note. This model was tested using two measures of external stress (i.e., external daily hassles and acute life events), one mediator (daily stress and tension arising within the relationship), and four variables hypothesized to reflect relationship functioning (i.e., marital satisfaction, sexual satisfaction, sexual activity, and sexual dysfunction).
Stress, sex, and satisfaction 565 satisfaction mean, sexual activity tends to decline with increasing levels of daily hassles. This pattern of results is not surprising, in the sense that stress does not appear to have adverse effects on women s sexual activity when their satisfaction is high and that higher levels of stress appear to covary with lower levels of sexual activity when their satisfaction is lower. Among men as a group, as with women, the sexual activity of relatively satisfied men does not appear to vary much as a function of their daily hassles. For men who are at or 1 SD below the mean in marital satisfaction, sexual activity tends to increase as daily hassles increase. Thus, the sexual activity of satisfied men, like that of maritally satisfied women, appears to be relatively independent of daily hassles. But unlike the pattern obtained for women, higher levels of daily hassles correspond with higher levels of sexual activity when men are at or below the sample mean in satisfaction, and this association appears to be stronger among those men with lower satisfaction. In short, our most basic prediction in Hypothesis 4 that higher levels of daily hassles will covary with higher levels of sexual activity was supported. In contrast, our predictions about the moderating role of marital satisfaction were only partly correct: Levels of sexual activity in the face of daily hassles were not higher among the most satisfied couples, and sexual activity declined with increases in daily hassles only for relatively distressed women but not for relatively distressed men. Discussion This study evaluated the associations among stressors arising outside of marriage (in the form of acute life events and daily stress), stressors arising within the relationship (in the form of daily relationship stresses and strains), and relationship functioning (indexed by marital satisfaction and sexual variables). We tested mediational hypotheses using the Actor Partner Mediator Model proposed by Ledermann and Bodenmann (2006), which extends the APIM (e.g., Kenny, 1996) often used with dyadic data. In undertaking this study, we aimed to test recent theoretical statements that assert that intimate relationships cannot be understood without reference to the contexts in which couples reside and specifically argue for distinguishing between stressors that are external and internal to the intimate dyad (see Bodenmann, 2000, 2005; Neff & Karney, 2004). Data were collected from both partners in 198 couples in established relationships, and actor and partner effects were analyzed in all models. Results support previous findings indicating that stress might play an important role in understanding marital functioning. Three sets of associations support this claim. First, whether measured as daily hassles or acute life events, partners reporting higher levels of stress arising outside the dyad also reported higher levels of stress and tension within the dyad. Partner effects were also evident, particularly for women s outcomes, indicating that external stress reported by men covaried more strongly with wives experience of daily relationship tension than vice versa. Second, spouses experiencing more stress as arising within the relationship tended to have lower levels of marital satisfaction, sexual satisfaction, and sexual activity, and higher levels of sexual dysfunction, and they tended to have partners with lower levels of marital satisfaction, sexual satisfaction, and sexual activity, though not a higher level of sexual dysfunction. Third, in the models suggesting partial mediation, men reporting more daily hassles external to the relationship reported more marital satisfaction and more sexual activity. These two latter results were relatively weak though reliable, and they permitted tests of internal stress as a mediator of associations between either form of external stress and relationship outcomes. In general, results provided support for the mediational framework outlined in Figure 1 and represented by Hypothesis 1. At least with the cross-sectional design used here, it seems that internal stress mediates the association between two forms of contextual variables external daily hassles and critical life events and key aspects of marital functioning such as marital satisfaction and sexuality. We can infer that different goals of the partners, divergent needs, and annoying habits (operationalized here as stress arising within the dyad) often become harmful for the relationship when partners are stressed by