Maintaining Emotion

. Another important aspect of the time course of emotional response is the maintenance of emotion (Davidson, 1994, 1998). From an affective science perspective, there is considerable agreement that emotional responses are relatively brief, phasic events that are organized along two opposing, overarching approach or avoidance motivational systems (e.g., Davidson, 1995; Dickinson & Dearing, 1979; Konorski, 1967; Lang, 1995). Furthermore,engagement of these approach or avoidance motivational systems through the maintenance of emotion is thought to facilitate goaldirected behavior toward something desirable or away from something noxious, respectively. In addition, there is some evidence to suggest that emotional responses that engage these motivational systems persist beyond the offset of the eliciting stimulus, as has been shown in studies with healthy individuals using self-report(e.g., Frost & Green, 1982; Garrett & Maddock, 2001), corrugator electromyographic activity (e.g., Bradley, Cuthbert, & Lang, 1996; Sirota, Schwartz, & Kristeller, 1987), pupillary dilation (e.g., Siegle, Granholm, Ingram, & Matt, 2001), amygdalar activity (e.g., Siegle, Steinhauer, Thase, Stenger, & Carter, 2002), and EEG asymmetry (e.g., Jackson et al., 2003; Larson & Davidson, 2001). One particularly effective method for assessing the time course of emotional response is the affective startle modulation paradigm. In this paradigm, activation of motivational systems exerts a modulatory influence on defensive startle responses, such that presentation of negatively valenced affective material engages an avoidance motivational system and primes associated behaviors (e.g.,Lang, 1994, 1995; Lang, Bradley, & Cuthbert, 1990, 1997). Thus,the magnitude of the eyeblink, one manifestation of the defensive startle reflex, elicited during the engagement of the aversive motivational system will be more potent than that of the same eye blink response engaged in the absence of this motivational activation. By contrast, presentation of positively valenced affective material engages an approach motivational state and primes appetitive behaviors. The eyeblink response component of the startle reflex elicited in an approach motivational context will be attenuated because of its incompatibility with the primed appetitive behaviors. A number of studies have examined the maintenance of affective modulation of the startle response by continuing to measure the eyeblink startle reflexive response following the offset of emotionally evocative stimulus presentation. With two exceptions(Bradley, Cuthbert, & Lang, 1993; Dichter, Tomarken, & Baucom,2002), these studies have found that an affective modulation of the startle response is maintained following picture presentation, such that eyeblink responses following the offset of unpleasant emotional stimuli are larger than eyeblink responses following the offset of pleasant emotional stimuli (Bradley et al., 1996; Germans Gard & Kring, 2007; Jackson et al., 2003; Larson & Davidson, 2001; Larson, Sutton, & Davidson, 1998; Schupp, Cuthbert, Bradley, Birbaumer, & Lang, 1997). Studies that found affective modulation of the startle response maintenance typically required participants to “do” something during the offset period, whether it was following an instruction to explicitly imagine that the picture is still there (e.g., Schupp et al., 1997) or following an implicit instruction to maintain emotion so that participants can report on their experienced emotion following the offset period (e.g., Germans Gard & Kring, 2007). Participants in the Bradley et al.(1993) study were asked to report on their experienced emotion following the offset period; however, these participants failed to show affective modulation of the startle response in the offset period, perhaps due to the time at which the startle response was measured or the particular stimuli that were presented.