Taken together, Studies 1 and 2 suggest that positive emotions are unique, not in what they do to the cardiovascular system, but rather in what they can undo within this system. Put differently, the cardiovascular effects of positive emotions appear to emerge only when negative emotions have already generated cardiovascular reactivity.
Although the undoing effect of positive emotions now has demonstrated reliability, additional studies are needed to address lingering questions. For instance, what physiological mechanism mediates the effect? To date, we have explored changes in parasympathetic cardiac control (indexed by respiratory sinus arrhythmia, or RSA) both in the undoing paradigm (e.g., Study 1) as well as in comparisons across positive, neutral, and negative films (e.g., Study 2). In neither context have we observed any differences in RSA responses across experimental conditions. We thus tentatively conclude that the undoing effect of positive emotions does not occur through phasic changes in parasympathetic cardiac control. Discerning the operative underlying mechanism remains a task for future work.
Other questions linger as well. For example, is the undoing effect limited to the cardiovascular concomitants of emotions? Or, as the broaden-and-build theory would imply, can positive emotions also undo the cognitive and behavioral narrowing produced by negative emotions, and thereby restore flexible thinking and action? To the best of our knowledge, no experiments have tested this prediction directly. Even so, indirect evidence can be drawn from correlational studies. Individuals who express or report higher levels of positive emotion show more constructive and flexible coping, more abstract and long-term thinking, and greater emotional distance following stressful negative events (Keltner & Bonanno, 1997
; Martin, Kuiper, Olinger, & Dance, 1993
; Lyubomirsky & Tucker, 1998
; Stein, Folkman, Trabasso, & Richards, 1997
Another question to ask is whether evidence for the undoing effect also implies that positive emotions will buffer against cardiovascular reactivity triggered by subsequently experienced negative emotions. We have explored this possibility both empirically and theoretically. At an empirical level, we have reversed the order of film viewing used in Fredrickson and Levenson’s initial test of the undoing effect, showing people first the contentment, amusement, neutral, or sad film (by random assignment), and then showing the fear clip immediately after. No evidence for a buffering effect of positive emotions emerged (Fredrickson & Mancuso, 1996
). At a theoretical level, we concur with other theorists that personally relevant circumstances that elicit negative emotions should reliably interrupt people’s actions and capture their attention, both psychologically and physiologically (Levenson, 1994
; Mandler, 1984
; Pratto & John, 1991
; Simon, 1967
; Tomkins, 1995
). We suspect that such interruption should occur no matter what people’s prior affective state. Thus, we speculate that positive emotions do not buffer against negative emotional arousal in any direct or simple way. Even so, positive emotions might, over time, bolster people’s resources for coping with circumstances that elicit negative emotions. That is, positive emotions might play an indirect buffering role by incrementing coping resources (Folkman & Moskowitz, 2000
). These coping resources might take the form of the physical, intellectual, or social resources described by Fredrickson’s broaden-and-build theory of positive emotions (Fredrickson, 1998
), the hedonic surplus described by Aspinwall (1998)
, or—if the undoing effect of positive emotions were deployed regularly to speed recovery from negative emotions—the physiological toughness described by Dienstbier (1989)
In sum, the work reported here illuminates one reason, beyond intrinsic pleasure, for the pursuit of happiness: Positive emotions help downregulate the potentially health-damaging cardiovascular reactivity that lingers following negative emotions. This effect may be especially critical for those most at risk for developing coronary heart disease. Nonetheless, the undoing effect is likely to be just one of many reasons to pursue positive emotions. The broaden-and-build theory describes many others (Fredrickson, 1998
, in press-a
, in press-b
). Chief among these is that experiences of positive emotions are thought to build individuals’ lasting personal resources. By consequence, positive emotions could be tapped to optimize people’s health and well-being (Fredrickson, 2000
). It appears then that we have reasons other than pure hedonism to pursue positive emotions. Evidence that positive emotions do more than simply feel good underscores the need to study them further.