Cardiovascular reactivity during performance under social observation: The moderating role of task difficulty Guido H.E. Gendolla ⁎ , Michael Richter FPSE, Department of Psychology, University of Geneva, 40, Bd. du Pont d'Arve, CH-1211 Geneva 4, Switzerland Received 2 February 2006; received in revised form 9 March 2006; accepted 11 April 2006 Available online 5 June 2006 Abstract An experiment with N = 40 university students investigated the impact of social observation on cardiovascular reactivity during performance on a computer-based letter detection task. The study was conducted in a 2 (social observation: no vs. yes) × 2 (task difficulty: easy vs. difficult) between-persons design. In accordance with engagement-related predictions about the role of social observation in active coping, the mere presence of an experimenter who observed participants during task performance increased the reactivity of systolic blood pressure when the task was difficult, but not when the task was easy. Without social observation, reactivity was modest in both the easy and the difficult conditions. Reactivity of diastolic blood pressure described the same pattern as systolic blood pressure. Results are interpreted as evidence for an effort-related analysis of cardiovascular reactivity based on the principles of motivational intensity theory. © 2006 Elsevier B.V. All rights reserved. Keywords: Cardiovascular reactivity; Social observation; Active coping; Mental effort 1. Introduction Reactions of the autonomic nervous system during task performance under social observation have been of interest since Zajonc (1965) proposed that the presence of others increases the level of “drive” or “general arousal” and thus moderates task performance (see Hull, 1943). After decades with modest evidence of social observation effects on autonomic nervous system activity (see Geen and Bushman, 1989) there is now accumulating evidence of effects on one specific autonomic parameter: cardiovascular arousal (e.g., Hartley et al., 1999; Pruyn et al., 1985; Schwerdtfeger, 2004; Smith et al., 1997, 2000; Wright et al., 2002, 1995). We investigated social observation effects on cardiovascular reactivity from a specific theoretical perspective—an applica- tion of Wright's (1996) integration of Obrist's (1981) active coping approach with Brehm's theory of motivational intensity (Brehm and Self, 1989) to performance conditions that involve the performer's self (Gendolla, 2004). According to Wright's (1996) integrative analysis, the impact of the sympathetic nervous system on the heart and the vasculature responds proportionally to subjective task difficulty as long as success is possible and worthwhile. Especially, systolic blood pressure has been found to respond reliably to task demand (e.g., Bongard, 1995; Gendolla and Krüsken, 2001a, 2002a,b; Gerin et al., 1995; Light, 1981; Lovallo et al., 1985; Obrist, 1981; Sherwood et al., 1990; Smith et al., 1997, 2000). Evidence for effects on diastolic blood pressure and heart rate (Gendolla, 1999; Gendolla and Richter, 2005; Obrist, 1981; Schwerdtfeger, 2004) is existent but less consistent—presumably because systolic blood pressure is more systematically influenced by sympathetic discharge to the heart than diastolic blood pressure and heart rate (Brownley et al., 2000). Wright and colleagues have demonstrated that cardiovascu- lar reactivity in the context of task performance increases proportionally to the extent of subjective demand until a fixed difficulty level exceeds a person's abilities (i.e. active coping is too difficult and thus impossible) or the amount of necessary effort for active coping is not justified by the importance of success (see Wright, 1996; Wright and Kirby, 2001 for reviews). Furthermore, the integrative analysis suggests that the impor- tance of success directly determines cardiovascular reactivity when task difficulty is unfixed, i.e. when people are asked to International Journal of Psychophysiology 62 (2006) 185 – 192 www.elsevier.com/locate/ijpsycho ⁎ Corresponding author. E-mail address: Guido.Gendolla@pse.unige.ch (G.H.E. Gendolla). 0167-8760/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ijpsycho.2006.04.002