Attitude Similarity and Familiarity and Their Links to Mental Health: An Examination of Potential Interpersonal Mediators

Abstract

Similarity and familiarity with partner's attitudes (Byrne, Clore, & Smeaton, 1986; Sanbonmatsu, Uchino, & Birmingham, 2011) are linked to positive relationship outcomes, while interpersonal variables have been linked to mental health (e.g., Lakey & Cronin, 2008). Using multilevel models (MLMs), we modeled the associations between these attitudinal variables and mental health outcomes in 74 married couples. We found that higher levels of attitude similarity in couples were linked to lower depression, while higher levels of attitude familiarity in couples were associated with greater satisfaction with life. Mediational analyses indicated marital satisfaction and interpersonal stress mediated the link between attitude similarity and depression. Marital satisfaction also mediated the link between familiarity and satisfaction with life. This study is the first linking attitude familiarity to mental health and provides evidence that familiarity and similarity have mental health effects partly due to their interpersonal consequences.

Attitudes have long been recognized to play a central role in guiding individual behavior and decisions (e.g., Ajzen & Fishbein, 1977; Blascovich, Ernst, Tomaka, Kelsey, Salomon, & Fazio, 1993). Attitudes are evaluations of and feelings toward objects, persons, situations, issues, events, and behaviors that are stored in memory (e.g., Petty & Cacioppo, 1981; Sanbonmatsu, Posavac, Vanous, Ho, & Fazio, 2007). Increasingly, attitudes are also being shown to play an important role in interpersonal behavior and relationships. Several studies have found that similarity in attitudes is related to partners' liking of one another (Byrne, Clore, & Smeaton, 1986; Gaunt, 2006; Luo & Kohnen, 2005). More recently, research has shown that familiarity with partners' attitudes may be vital to providing support, avoiding conflict, and maintaining close relationships (Sanbonmatsu, Uchino, Wong, & Seo, 2012). The interpersonal benefits of attitude similarity and attitude familiarity are important because they have been linked to physical health outcomes (Sanbonmatsu, Uchino, & Birmingham, 2011). Our research investigated the possibility that these benefits extend to mental health as well. More specifically, we examined whether attitude similarity and familiarity have important mental health consequences through their effects on interpersonal functioning.

Attitude Similarity and Interpersonal Functioning

Prior work has established that similar people are attracted to one another and have closer and more lasting relationships (Byrne et al., 1986; Gaunt, 2006; Luo & Klohnen, 2005). One specific measure of similarity in couples is attitude similarity. Attitude similarity refers to the extent to which individuals' attitudes are similar to one another. Luo and Kohnen (2005) measured similarity in terms of couples' personality traits, as well as values, political attitudes, and religiosity and concluded that while similar personalities are linked to marital satisfaction, similar values, attitudes (in this case, political attitudes), and religiosity were not related to marital satisfaction. A related study found that while similarity in personality traits and value domains showed a strong and consistent association with relationship satisfaction, similarity of attitudes (i.e., attitudes toward family roles) and religiosity showed weaker, less consistent patterns (Gaunt, 2006). Previous studies may have failed to find an association between attitude similarity and relationship quality because the measurement of attitudes was limited to narrow domains (i.e., political attitudes and attitudes toward family roles). We anticipated that a broader measure of the similarity of partners' likes and dislikes would be more predictive of interpersonal processes.

Attitude Familiarity and Interpersonal Functioning

A more recently developed construct is attitude familiarity, which refers specifically to knowledge of another person's attitudes. Couples in general tend to have more accurate impressions of one another than those not in interdependent relationships (Fiske & Neuberg, 1990). Greater knowledge of one's partner has been linked to successful relationship outcomes, such as greater feelings of partner intimacy (Swann, De La Ronde, & Hixon, 1994) and greater relationship satisfaction (Gottman, 1994). Furthermore, Swann, Hixon, and De La Ronde (1992) found that when people have negative self-views, they “displayed more commitment to spouses who evaluated them unfavorably than to spouses who evaluated them favorably” (p. 120). Thus, there are even positive consequences for relationships when a partner verifies a spouse's negative identity. Neff and Karney (2005) found that the extent to which wives' perceptions of their husbands' traits matched their husbands' self-reports predicted higher feelings of control in the relationship, more support behaviors, and a decreased likelihood of divorce.

Prior research indicates that our own attitudes guide information processing (Lord, Ross, & Lepper, 1979), appraisals of situations and response alternatives (Sanbonmatsu & Fazio, 1990), and behavior (Ajzen & Fishbein, 1977). Familiarity with the attitudes of others may be similarly functional, enabling an individual to more easily avoid conflict and better fulfill partners' support needs. Sanbonmatsu et al. (2011) found that partners more familiar with each other's attitudes reported more positive interactions and higher state self-esteem during daily life. A follow-up study (Sanbonmatsu et al., 2012) found that familiarity with partners' attitudes was associated with reports of lower fighting and upsetting one another, more helpful behavior, and higher levels of affiliation.

Attitude similarity is positively correlated with attitude familiarity (Sanbonmatsu et al., 2012). However, prior research indicates that attitude similarity and familiarity, while overlapping, are distinct from one another. Sanbonmatsu et al. (2012) found that attitude familiarity continued to predict less fighting, conflict and upset, somewhat greater affiliation, and global relationship importance after statistically controlling for the effects of attitude similarity. Thus, it does not appear that attitude familiarity is simply capturing the effects of attitude similarity. Research supports the idea that the two constructs are differentially related to interpersonal variables like conflict and support.

Attitudinal Processes, Interpersonal Functioning, and Mental Health

Based on prior research, we expected both attitude similarity and familiarity would be linked to interpersonal outcomes. Might these links have consequences for mental health? At a broad level, the break-up of a romantic relationship has been associated with increases in psychological distress and declines in life satisfaction (e.g., Rhoades, Kamp Dush, Atkins, Stanley, & Markman, 2011). Additionally, important interpersonal variables such as social support are linked to lower rates of depression (Lakey & Cronin, 2008), lower levels of psychological distress (Barrera, 1986; Cohen & Wills, 1985), and negative affect (Finch, Okun, Pool, & Ruehlman, 1999).

Prior research on trait similarity in couples suggests that attitude similarity would also have mental health consequences. Trait similarity in couples is linked to happiness. For instance, when both partners rated high on femininity, they reported being happier than couples where one partner was low on femininity (Antill, 1983). Arrindell and Luteijn (2000) studied married or cohabiting couples and measured several personality dimensions, finding that higher satisfaction with life was linked to greater similarity in partners' personalities.

We have proposed previously that one benefit of attitude familiarity is its influence on interpersonal processes, such as the provision of social support. Greater knowledge of a partner's preferences should allow a person to provide his or her partner with better support. While attitude familiarity has not been directly tied to social support, various findings support this link. Greater levels of attitude familiarity are associated with reporting more positive interactions (Sanbonmatsu et al., 2011), less fighting and upset, and more helpful behavior (Sanbonmatsu et al., 2012). All of these findings point to the likelihood that attitude familiarity would be associated with greater social support within couples, and this influence may be one way in which attitude familiarity's influence on interpersonal processes would also influence mental health.

Previous research strongly suggests that attitude familiarity and similarity would be related to interpersonal constructs, such as marital satisfaction and interpersonal stress. Additionally, research has linked certain aspects of relationships to mental health outcomes. We hypothesized that attitude familiarity and similarity are linked to mental health through their effects on interpersonal processes. That is, couples that are more familiar with one another's attitudes are also likely more satisfied and experience less conflict. Because of this, we would expect to see mental health benefits also. Couples that have similar attitudes may also be happier because they experience less conflict and higher marital satisfaction. It is important to determine whether attitude familiarity and similarity are related to mental health because it could provide another avenue through which to target improvements in treating people for depression or increasing one's subjective well-being.

The Present Study

The current study sought to establish the links between attitude similarity and familiarity, and mental health, and the potential interpersonal mediators. We thus first examined whether attitude similarity in couples was associated with the mental health outcomes of depression and satisfaction with life, and the relational outcomes of marital satisfaction and interpersonal stress. We then examined those outcomes and their associations with attitude familiarity. Finally, we entered these variables into the model simultaneously to test if attitude similarity and familiarity were unique associations. Following past work, it was hypothesized that attitude similarity and attitude familiarity would be associated with marital satisfaction and interpersonal stress. Additionally, we predicted that attitude similarity and familiarity would be linked to mental health and that their effects on relationship functioning would mediate these associations.

Methods

Participants

Seventy-four couples were included in the study. The participants were largely middle-aged (mean age = 56.06), college educated, and White (95.9%), with an average yearly income of $30,000 – $40,000. Because this was part of a larger study of spousal relationship quality and inflammation (Uchino et al., 2013), participants were excluded if they were currently on strong immunosuppressive treatment, or had HIV or cancer. Participants received monetary compensation for serving in the study.

Procedure

Participants were recruited through advertisements placed in local newspapers, workplace newsletters, and flyers distributed around the community. Potential participants were screened for eligibility and informed consent was obtained. Eligible couples filled out questionnaires, presented in a fixed order. They first filled out demographic and health questionnaires, followed by relationship assessments, and then finished by completing the attitude scales (see below). Spouses completed the questionnaires in the same room. One partner sat in a chair and the other partner sat on a couch on the opposite side of the room. They were unable to see each other's questionnaires and were instructed not to share their answers. They were also guaranteed that their responses would not be shared with their spouse.

Measures

Attitude familiarity and similarity

Participants indicated their evaluations of 25 different attitude objects on 7 point scales anchored by -3 very negative and +3 very positive. The items were selected to broadly sample different attitudinal objects (e.g., money, Wal-Mart, guns, recycling) and have been used in our prior work on attitudinal processes (e.g., Fazio, Sanbonmatsu, Powell, & Kardes, 1986; Sanbonmatsu et al., 2011). Spouses also indicated their perceptions of their partners' evaluations of the same targets on the same scale.

Separate attitude familiarity scores were calculated for each spouse by determining the correlation between each spouse's ratings of his/her partner's attitudes toward the 25 attitude objects and his/her partner's actual reported attitudes. The average level of attitude familiarity in the sample was r = .66 (range .15 to .92). These correlations were transformed into z scores using Fisher's r to z transformation and averaged across spouses to create a couple score of attitude familiarity that was used in all analyses.

Attitude similarity scores for each couple were calculated by determining the correlation between each spouse's attitudes toward the 25 attitude objects. The average level of attitude similarity in the sample was r = .47 (range -.05 to .87). These correlations were transformed into z scores using Fisher's r to z transformation for subsequent analyses.

Marital satisfaction

The Marital Adjustment Test (MAT; Locke & Wallace, 1959) is a 15-item scale that is widely used to measure the overall quality of marital relationships. It has good psychometric properties and is able to reliably differentiate between non-distressed and distressed married couples.

Interpersonal stress

The Test of Negative Social Exchange (TENSE; Ruehlman & Karoly, 1991) is an 18 item assessment of the extent of conflict in social interactions. The measure has strong psychometric properties and provides an overall assessment of interpersonal stress related to hostility/impatience, insensitivity, interference, and ridicule. This was a measure of general interpersonal stress—not specific to one's partner.

Depression

The Center for Epidemiologic Studies Depression Scale (CES-D; Radloff, 1977) is a 20 item assessment that measures depressive symptoms. Participants indicate how often they have experienced a depression-related symptom in the past week. The scale is widely used and has demonstrated good psychometric properties.

Satisfaction with life

The Satisfaction with Life scale (SWL) is widely used and measures participants' global judgments of their satisfaction with life (Diener, Emmons, Larsen, & Griffin, 1985). It has strong psychometric properties including good internal consistency and test-retest reliability (Diener et al., 1985).

Statistical analyses

The research questions in the current study focus on how spouses' attitude familiarity and similarity are related to depression, interpersonal stress, marital satisfaction, and satisfaction with life. A series of multilevel models (MLMs) was used to model associations between attitudinal familiarity/similarity and these mental health outcomes while controlling for age, income, education, and gender—standard demographic controls which prior research indicates would be relevant. The following equation illustrates the series of equations for the 2-level model used to examine the association between marital satisfaction and attitude familiarity:

Level-1:

$${\mathit{\text{Marital Satisfaction}}}_{ti}^{\ast }={\pi }_{\mathit{0}i}+{\pi }_{\mathit{1}i}\ast ({\mathit{\text{Gender}}}_{ti})+{\pi }_{\mathit{2}i}\ast ({\mathit{\text{Age}}}_{ti})+{\pi }_{\mathit{3}i}\ast ({\mathit{\text{Income}}}_{ti})+{\pi }_{\mathit{4}i}\ast ({\mathit{\text{Education}}}_{ti})+{\varepsilon }_{ti}$$

Level 2:

$${\pi }_{\mathit{0}i}={\beta }_{\mathit{00}}+{\beta }_{\mathit{01}}\ast (\mathit{\text{Attitude}}{\mathit{\text{Familiarity}}}_i)+r_{\mathit{0}i}$$

for t = 1 to 4, π_ti = β_t0

where t indexes partners and i indexes couples. Separate, identical models were run with interpersonal stress, satisfaction with life, and depression as the dependent variable and with attitude similarity substituted for attitude familiarity at level-2. Finally, attitude familiarity and similarity were both included as predictors in models for each outcome. We also examined the interpersonal variables of interpersonal stress and marital satisfaction as potential mediators in predicting depression and satisfaction with life. In all models, attitudinal variables were averaged across spouses and grand mean centered, resulting in single couple scores of attitude familiarity and similarity. This was done in order to allow for examination of between couple associations between attitudinal variables and outcomes. Additionally, age, income, and education were grand mean centered at level-1 to control for within- and between-couple effects of these covariates (Enders & Tofighi, 2007). All MLMS were run in HLM, version 7 (Raudenbush, Bryk, Cheong, Congdon, & du Toit, 2011).

Results

We first examined associations from separate models for attitude similarity (see Table 1) and attitude familiarity separately (see Table 2)¹. In these analyses, higher levels of attitude similarity were significantly associated with lower interpersonal stress, higher marital satisfaction, and lower depression. In comparison, greater attitude familiarity was significantly associated with lower levels of interpersonal stress, higher levels of marital satisfaction, and higher levels of satisfaction with life.

Table 1. Regression Coefficients for Attitude Similarity and Covariates from Separate Model.

Outcomes	Marital Satisfaction		Interpersonal Stress		Depression		Satisfaction with Life
Predictors	B	SE B	B	SE B	B	SE B	B	SE B
Attitude Similarity	14.62*	7.35	-.39**	.15	-4.38**	1.60	.98	1.29
Age	-.33	.29	.00	.01	-.06	.06	-.03	.05
Income	1.73	1.86	-.06	.04	-1.00*	.41	.42	.33
Gender	-.34	3.22	-.12	.08	-.51	.86	1.48**	.59
Education	1.25	1.42	-.02	.03	-.37	.34	.31	.26

^*Note: p ≤ .05,

^**p ≤ .01,

^***p ≤ .001

Table 2. Regression Coefficients for Attitude Familiarity and Covariates from Separate Model.

Outcomes	Marital Satisfaction		Interpersonal Stress		Depression		Satisfaction with Life
Predictors	B	SE B	B	SE B	B	SE B	B	SE B
Attitude Familiarity	28.07**	8.72	-.41*	.19	-3.03	2.04	3.42*	1.55
Age	-.18	.28	.00	.01	-.08	.07	-.02	.05
Income	1.08	1.75	-.04	.04	-.77	.41	.40	.31
Gender	-.10	3.21	-.13	.08	-.59	.86	1.49**	.59
Education	.97	1.39	-.02	.03	-.42	.35	.25	.25

^*Note: p ≤ .05,

^**p ≤ .01,

^***p ≤ .001

Turning to models where attitude similarity and familiarity were simultaneously included as predictors (see Table 3), associations between higher levels of attitude similarity and lower levels of depression remained significant (B = -4.25, p = .02). Similarly, associations between higher levels of attitude familiarity and higher marital satisfaction (B = 25.58, p < .01) as well as higher levels of satisfaction with life (B = 3.80, p = .04) remained significant. In contrast, associations between attitude similarity and marital satisfaction (B = 3.92, p = .63) and attitude similarity and interpersonal stress (B = -.30, p = .09), as well as associations between attitude familiarity and interpersonal stress (B = -.22, p = .30) that were significant in the separate models were non-significant in the combined model.

Table 3. Regression Coefficients for Attitude Similarity, Familiarity, and Covariates from Combined Model.

Outcomes	Marital Satisfaction		Interpersonal Stress		Depression		Satisfaction with Life
Predictors	B	SE B	B	SE B	B	SE B	B	SE B
Attitude Similarity	3.92	8.24	-.30	.17	-4.25*	1.87	-.60	1.46
Attitude Familiarity	25.58**	10.16	-.22	.21	-.33	2.31	3.80*	1.80
Age	-.20	.28	.00	.01	-.06	.06	-.01	.05
Income	1.29	1.80	-.06	.04	-1.0*	.41	.36	.32
Gender	-.16	3.21	-.12	.08	-.51	.86	1.50**	.59
Education	.93	1.39	-.02	.03	-.38	.34	.26	.25

^*Note: p ≤ .05,

^**p ≤ .01,

^***p ≤ .001

Finally, interpersonal stress and marital satisfaction were examined as potential mediators of associations between attitude similarity and depression and attitude familiarity and satisfaction with life given the independence of these links. The magnitude of mediated effects were determined by calculating the difference between the estimated coefficient for the attitudinal predictor without the mediator included in the model minus the estimated coefficient for the attitudinal predictor with the mediator included in the model (i.e., C – C'; MacKinnon, 2008; Preacher & Hayes, 2004; Rucker, Preacher, Tormala, & Petty, 2011). The significance of these mediated effects was assessed using recommended procedures for estimating nonparametric bootstrapped confidence intervals in MLMs (i.e., empirical M tests; Preacher & Hayes, 2004; Tofighi & MacKinnon, 2011). Significant mediation is considered to occur when the bootstrapped 95% confidence interval does not include 0.

We first examined whether marital satisfaction mediated the relationship between attitude similarity and depression. Results were consistent with mediation (C – C' = -1.24, 95% CI: -2.88 to -.02). Interpersonal stress was also examined to determine whether it mediated the relationship between attitude similarity and depression. Results were again consistent with mediation (C – C' = -1.30, 95% CI: -2.92 to -.19). Analyses next aimed at examining the interpersonal mediators of the link between attitude familiarity and life satisfaction produced results consistent with mediation for marital satisfaction (C – C' = 1.11, 95% CI: .01 to 2.7) but not interpersonal stress (C – C' = .72, 95% CI: -.07 to 1.99).

Discussion

The main contribution of our study was to show that knowledge of partner's attitudes and similarity in partners' attitudes are associated with mental health. Attitude familiarity was significantly associated with higher levels of satisfaction with life, an association that was mediated by marital satisfaction. In addition, attitude similarity was linked to lower depression, which was mediated by both marital satisfaction and interpersonal stress. This appears to be the first study showing these associations between these attitudinal processes in couples and mental health outcomes as well as the mechanisms responsible for such links. Importantly, these mechanisms indicate that our findings regarding attitude familiarity and similarity correspond with the many other studies that link interpersonal variables to mental health consequences (Rhoades et al., 2011; Lakey & Cronin, 2008; Barrera, 1986; Cohen & Wills, 1985; Finch et al., 1999).

As we reviewed earlier, prior studies have linked trait similarity but not attitude similarity in couples to interpersonal functioning and mental health (Antill, 1983; Arrindell & Luteijn, 2000). We examined similarity in couples on a broader range of attitudinal topics than the narrower domains of political attitudes (Luo & Kohnen, 2005) or attitudes toward family roles (Gaunt, 2006) used in the past. Analyses showed that attitude similarity was significantly associated with lower depression in our study, even when controlling for attitude familiarity. Moreover, as we indicated above, our study was novel in showing that the link between similarity in couples and mental health is mediated by interpersonal processes.

An unexpected pattern that emerged in the study was that similarity in partners' attitudes significantly predicted depression while familiarity with partners' attitudes significantly predicted life satisfaction. The statistical meaningfulness of this pattern may be questionable, as the relation between attitude familiarity and depression also approached significance. Additionally, although attitude similarity was not associated with happiness in our study, Arrindell and Luteijn (2000) previously found that couples that were more similar on various personality dimensions reported higher satisfaction with life in a study characterized by greater statistical power. Nevertheless, there may be at least one theoretically-based reason for attitude similarity to be strongly linked to depression. Although similarity in attitudes affects liking (Byrne et al., 1986), the level of satisfaction with a relationship may be driven more heavily by the dissimilarity between partners (Rosenbaum, 1986). Measures of attitude similarity may be more predictive of negative mental health outcomes such as depression than positive mental health outcomes such as life satisfaction because dissimilarity contributes to discord more than similarity contributes to harmony.

Marital satisfaction and mental health have been associated with biased perceptions of partners and relationships (e.g., Fletcher & Kerr, 2010). This suggests an alternative model to the one that was investigated in our study in which relationship satisfaction and mental health influence perceptions of attitude similarity and familiarity. However, it is important to recognize that we did not measure perceived similarity or perceived familiarity in our study. Rather, we measured actual similarity in attitudes and actual knowledge of partners' attitudes—interpersonal factors that are not directly influenced by subjective biases. Nevertheless, there is the possibility that relationship satisfaction and mental health may affect the time partners spend together which, in turn, may affect their familiarity. Another possibility to consider is that couples that are more satisfied become more similar over time. However, past studies suggest that convergence in couples is unlikely. For example, Luo & Klohnen (2005) examined whether relationship length was linked to similarity in couples and concluded that partner similarity was likely not due to convergence.

There are several important limitations of the current study. First, inferences are necessarily limited by the cross-sectional design. Future longitudinal or laboratory research will be needed to address this limitation. Second, the study only looked at sub-clinical levels of mental health so generalizations to clinical samples are not warranted. Nevertheless, this study is the first to show that attitude familiarity and similarity are related to mental health, and that interpersonal processes mediate such links. Our research suggests that individuals who find romantic partners with similar likes and dislikes are more apt to have satisfying relationships which contribute to better mental health.

The findings further indicate that we may be able to improve relationships and, hence, mental health by learning more about our partner's attitudes. One intervention for couples that are struggling or simply hoping to improve upon their relationships may be to make a concentrated effort to learn more about each others' likes and dislikes. By doing this, we would expect improvements not only in the relationship but also for subjective well-being. Establishing feelings or likes that one has in common with a partner or simply learning more about a partner's preferences could also have far greater influence that we would initially suspect. These fairly simple attempts to establish common ground or learn more about another person could help us decrease the amount of conflict and make us more satisfied with that relationship. In addition to improving interpersonal relations, this could then ultimately enhance our own sense of well-being.