SUPPORT AND REACTIVITY HILMERT, KULIK, CHRISTENFELD The Varied Impact of Social Support on Cardiovascular Reactivity Clayton J. Hilmert, James A. Kulik, and Nicholas Christenfeld Department of Psychology University of California, San Diego Two experiments examine the hypothesis that the effect of social support on cardiovascular reac- tivity depends on participants’ evaluative concerns and their motivation for task performance. In both experiments, heart rate and blood pressure were recorded while participants gave a speech to either a supportive or nonsupportive audience, with the experimenter either present or absent. Ex- periment 1 showed that support decreased performer reactivity relative to nonsupport when the experimenter was present, whereas support increased reactivity when the experimenter was ab- sent. Experiment 2 replicated this pattern and helped clarify interpretation of the results. The re- sults may help resolve inconsistencies in previous support and reactivity literature, and suggest that social support may not always improve health by lowering cardiovascular reactivity. Research has indicated that there are important, health-re- lated advantages to having strong social relationships and ac- cess to social networks. These advantages include reduced risk of coronary heart disease (CHD) and essential hyperten- sion (EH; Berkman & Syme, 1994; Blumenthal, Burg, Bare- foot, & Williams, 1987; Cohen, 1988; House, Landis, & Umberson, 1988; House, Strecher, Metzner, & Robbins, 1986; Orth-Gomer & Unden, 1987, 1990; Seeman & Syme, 1987; Welin, Larsson, Svardsudd, & Tibblin, 1992). How- ever, the mechanisms by which social support benefits an in- dividual’s health are not well understood. One suggestion has been that social support influences individuals at a physi- ological level. Considerable effort has been devoted to inves- tigating the possibility that social support attenuates cardio- vascular reactivity (CVR) to stressful stimuli. According to the “reactivity hypothesis,” an excessive frequency of large magnitude, acute CVR episodes may contribute to the devel- opment of EH and CHD (Krantz & Manuck, 1984; Lovallo & Wilson, 1992; Manuck, Kamarck, Kasprowicz, & Waldstein, 1993; Pickering & Gerin, 1990), and so reducing these re- sponses can reduce the risk of cardiovascular disease (Uchino, Cacioppo, & Kiecolt-Glaser, 1996). In social support and CVR research, social support is commonly operationalized in the form of verbal and non- verbal agreement, the latter conveyed by nodding, smil- ing, and frequent eye contact. CVR is typically defined in terms of the magnitude of blood pressure (BP) and heart rate (HR) increases experienced during a stressful task. Most of this research has found that participants who re- ceive social support (usually from confederates) during a stressful episode exhibit less CVR than participants who do not receive support. For example, Gerin, Pieper, Levy, and Pickering (1992) found that female participants who were verbally attacked by two confederates during a de- bate showed less CVR when a third confederate supported their view than when the third confederate sat silently in the room. Lepore, Allen, and Evans (1993) also demon- strated that the presence of a supportive other reduced CVR to a speech task relative to performing the task alone or in the presence of a nonsupportive confederate. Other researchers have found that the presence of a supportive friend can reduce CVR to a task relative to performing the task alone or in the presence of a stranger (Christenfeld et al., 1997; Kamarck, Manuck, & Jennings, 1990; see Uchino et al., 1996, for a review). Although a considerable number of studies suggest that support can reduce CVR to a stressful task, the results are not completely consistent. Some researchers, for example, have failed to find evidence that participants experience less reactivity when facing a stressor in the presence of a friend rather than alone (Edens, Larkin, & Abel, 1992; BASIC AND APPLIED SOCIAL PSYCHOLOGY, 24(3), 229–240 Copyright © 2002, Lawrence Erlbaum Associates, Inc. Requests for reprints should be sent to Clayton J. Hilmert or James A. Kulik, Department of Psychology, 9500 Gilman Drive, University of Cali- fornia, San Diego, La Jolla, California 92093–0109. E-mail chilmert@ucsd.edu or jkulik@ucsd.edu