Subliminal activation of social ties moderates cardiovascular reactivity during acute stress.

Social relationships are an omnipresent part of life. Importantly, supportive relationships have been reliably associated with beneficial physical health outcomes (Barth, Schneider, & von Kanel, 2010; Holt-Lunstad, Smith, & Layton, 2010; House, Landis, & Umberson, 1988). Moreover, a smaller but growing literature is consistent with the health risks associated with negative social ties (De Vogli, Chandola, & Marmot, 2007; Friedman et al., 1995). Consistent with these epidemiological literatures, positive social interactions decrease cardiovascular reactivity during stress (i.e., buffering hypothesis of support, Thorsteinsson & James, 1999), whereas negative interactions exacerbate reactivity (Ewart, Taylor, Kraemer, & Agras, 1991). These data are important because increased cardiovascular reactivity to stressors has been linked to cardiovascular disease risk (Chida & Steptoe, 2010). Much of the prior work on relationships and physiological stress responses has examined direct social interactions (Uchino, 2009). For instance, studies have shown that the provision of social support can attenuate cardiovascular responses to stressful tasks (Lepore, 1998; Uchino, Cacioppo, & Kiecolt-Glaser, 1996), although under certain situations (e.g., Lepore, 1995; Taylor et al., 2010), received social support is not associated with reduced cardiovascular reactivity. On the other hand, perceptions of support are more consistently related to beneficial health outcomes than is received support (Barrera, 2000; Uchino, 2004). This could be because received support can convey the message that the recipient is incapable of managing difficulties on their own, thereby threatening self-esteem or perceptions of independence (Bolger, Zuckerman, & Kessler, 2000; Martire, Stephens, Druley, & Wonjo, 2002; Nadler & Fisher, 1986). Perceived support, in contrast, provides benefits without these drawbacks (Uchino, 2009). In fact, perceived and received support are at best moderately correlated and hence separable constructs (Wills & Shinar, 2000). The role of perceptions of support, rather than the actual receipt of support, in stress buffering has been demonstrated in studies that show simply calling to mind feelings of connectedness and support can attenuate CVR to a stressor task (Ratnasingam & Bishop, 2007; Smith, Ruiz, & Uchino, 2004). For instance, Smith and colleagues (2004) used a supraliminal prime by having participants write about a supportive tie (e.g., what you appreciate about this person) or casual acquaintance and then had them perform psychological stressors. Results revealed that writing about a supportive tie was associated with lower cardiovascular reactivity to a subsequent speech stressor compared to writing about a casual acquaintance (also see Ratnasingam & Bishop, 2007). One important question that arises from these studies is how automatic are the cognitive processes linking relationships to cardiovascular function? Given that in the studies above, no actual provision of support occurred, it is possible that subliminal (nonconscious) activation of relationship representations could impact self-regulatory processes, with subsequent implications for physiological reactivity while coping with stress. This possibility is consistent with the general view that people construct working models of their relationships with others that include self-and-other schemata (Baldwin, 1992; Ogilvie & Ashmore, 1991). Thus, activation of a relational schema could cause spreading-activation and individuals could then experience themselves in the way that they normally do when with the relationship partner even in the absence of the actual relational tie (Andersen & Berk, 1998; Baldwin, 1990). If subliminal activation of relationship representations influences stress responses, such effects would suggest a novel and potentially far-reaching mechanism by which social relationships influence susceptibility to disease. That is, if subliminal activation of working models alters physiological stress responses, then relationship quality could influence health-relevant physiological processes well beyond circumstances involving actual or even conscious recollection of positive or negative relationship experiences. The quality of one’s social life could influence pathophysiological processes and resulting health risks much more pervasively, through the myriad subtle reminders of relationships encountered during everyday experience (e.g., pictures, names). A first aim of the current study was thus to examine if subliminal activation of relationships can influence health-relevant physiological processes during stress. We focused on systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) given that these measures have been linked to significant health outcomes (Chida & Steptoe, 2010). We also examined respiratory sinus arrhythmia (RSA) as an index of vagal control of the heart. RSA is the rhythmical fluctuation in heart period occurring at the respiration band (i.e., 0.12–0.40 Hz) that is associated with a shortening and lengthening of heart periods during inspiration and expiration, respectively (Bernston, Cacioppo, & Quigley, 1993b). RSA is receiving greater attention as a health-relevant biological index associated with self-regulatory processes due to its links to prefrontal cortical areas (see Berntson et al., 1994; Thayer, Hansen, Saus-Rose, & Johnsen, 2009). Thus, if subliminal activation of relationships influences self-regulatory processes (for better or worse) than it may be closely linked to RSA (Thayer et al., 2009). A second aim of our study was to examine these questions in the context of a more general model on the health effects of relationships (Uchino, Holt-Lunstad, Uno, & Flinders, 2001, see Figure 1). Most prior health research has focused on positive aspects of relationships. However, a growing body of literature is consistent with the deleterious health effects of negativity in relationships (De Vogli et al., 2007). Such links are generally consistent with a "negativity bias" in which such stimuli have stronger influences across various outcomes (Taylor, 1991). In addition, little research has examined the joint or interactive effects of these two common relationship experiences (Uchino, Holt-Lunstad, Uno, Campo, & Reblin, 2007). According to our model, a person falling in the high positivity/low negativity category would be a strong source of social support (e.g., the best friend you can always count on). In contrast, a network member who falls in the category of low positivity/high negativity would represent an aversive network tie (e.g., an unreasonable manager). Network members who exhibit low positivity/low negativity are people whom we come into contact with very low frequency or depth (e.g., the next-door neighbor). Relatively unique relationship ties that are salient due to this conceptual framework fall into the high positivity/high negativity category and are labeled ambivalent ties (e.g., overbearing parent, volatile romance). In our prior work, most of these network types are either family or friends, with no consistent evidence for gender differences in links between these relationship types and health outcomes (Campo et al., 2009). Figure 1 A general framework for examining positive and negative aspects of relationships on health. In the present study, we used a subliminal priming technique to activate relationship representations related to supportive, aversive, ambivalent, and indifferent network ties. In contrast to prior work, by utilizing a subliminal priming procedure, we evaluated whether relationships that are automatically activated in memory influence reactivity, rather then due to any conscious appraisal on the part of the individual or through direct behavioral interactions. We predicted that subliminal activation of ambivalent ties would heighten cardiovascular reactivity, as would negative ties, albeit to a lesser extent. These predictions were based on the fact that ambivalent ties are sources of both positive and negative interactions, making them less predictable which has been associated with potentiated physiological responses (Uchino et al., 2007). In addition, ambivalent ties are typically described as "close," and hence there is more of an overlap between self-other representations (Aron, Aron, Tudor, & Nelson, 1991) which can exacerbate stress responses. In contrast, aversive ties are not likely to have considerable self-other overlap which should lessen any effects on self-related coping processes. These predictions are consistent with our prior work linking ambivalent ties to adverse influences on cardiovascular functioning (Holt-Lunstad, Uchino, Smith, Cerny, & Nealey-Moore, 2003; Holt-Lunstad, Uchino, Smith & Hicks, 2007; Reblin, Uchino, & Smith, 2010). We also predicted that activation of supportive ties would reduce reactivity, consistent with the buffering model and prior research on the effects of social support on physiological stress responses. Indifferent ties were expected to elicit a middle-level response, such that they should be associated with lower levels of cardiovascular reactivity than ambivalent or aversive ties, and higher reactivity than supportive ties. Finally, an exploratory aim was to examine the psychological processes that might also be related to subliminal activation of such relationships. Thus, we measured pre-task perceptions of threat, coping, and control. However, given inconsistencies between self-report and cardiovascular assessments, our primary hypotheses focused on the health-relevant measures of cardiovascular reactivity during stress (Gerin, Pieper, Levy, & Pickering, 1992).