The current study sought to examine emotional reactivity in nonsuicidal self-injury (NSSI) using self-report and psychophysiological measures of emotion. Self-report findings from the present study are consistent with previous research suggesting that individuals who engage in NSSI experience more negative emotionality and greater interference from this emotional distress than noninjuring controls (Gratz & Roemer, 2008
; Heath et al., 2008
). However, although self-injurers reported greater emotional reactivity, there were no differences in the affective modulation of startle during emotional picture viewing (assessing emotional reactivity) or after emotional picture offset (assessing emotional recovery) between self-injurers and noninjuring controls. The null startle results and divergence between self-report and psychophysiological measures of emotion is surprising given the robust self-report findings from this and previous studies on NSSI.
Although the startle findings do not support previous research on emotional abnormalities in NSSI, results do mirror previous null findings in startle responding in borderline personality disorder (BPD), a disorder closely associated with NSSI. A few studies have failed to find differences between patients with BPD and controls in baseline startle, prepulse inhibition of startle (Herpertz et al., 2000
), and affective modulation of startle (Herpertz & Koetting, 2005
). Both NSSI and BPD share features of increased negative emotionality and difficulty with emotion regulation (Clarkin & Posner, 2005
; Klonsky et al., 2003
). Thus, the failure in this and other studies to document emotional abnormalities in these conditions using peripheral psychophysiological measures is somewhat perplexing.
Despite the lack of group differences, findings from this study indicate that, across participants, affective modulation of startle was maintained, albeit weaker, after picture offset. These findings are in line with some previous research examining affective modulation of startle in the postpicture period (Dillon and LaBar, 2005
; Schupp et al., 1997
). However, previous studies have only reported affective modulation of startle in the postpicture period when participants were instructed to imagine the picture or to enhance their emotional experience. The current results, on the other hand, suggest that affective modulation of startle is evident after picture offset without direct instruction. Moreover, potentiation to aversive stimuli was comparable between the picture viewing and postpicture periods, whereas attenuation to appetitive stimuli was reduced in the postpicture period. These findings support the notion of a negativity bias in emotional recovery, or greater sensitivity to negative than positive stimuli in the postpicture period (Ito et al., 1998
); however, the appetitive stimuli used in the current study were rated as less arousing than the aversive stimuli so these findings should be interpreted with caution. Collectively, the current results provide support for the notion that the startle reflex can be used to measure both emotional reactivity to, and recovery following, emotional stimuli.
This study is the first to examine affective modulation of startle in NSSI and contributes to the growing literatures on emotion in NSSI as well as affective modulation of the startle reflex in the postpicture period. However, several important limitations deserve comment. First, findings suggest that the two components of emotional processing explored in the present study may not tap into emotionality differences central to NSSI. For instance, it is possible that reactivity to and initial recovery from an emotional challenge are equivalent in self-injurers and noninjurers. However, this interpretation seems unlikely given the robust self-report evidence to the contrary. Another possibility is that the standardized emotional images used in this study were not comparable to real-world emotional stimuli and therefore failed to elicit the emotion dysregulation in NSSI that occurs outside the laboratory. Perhaps more idiographic stimuli, such as negative feedback or other personally relevant information, would be useful for examining emotion regulation difficulties in NSSI. In addition, it may be possible that reactivity and recovery differences in NSSI may only emerge during a heightened emotional state (e.g., frustration). For instance, perhaps self-injurers would show differences in startle reactivity or recovery if a mood induction preceded the picture viewing task. Second, the sample was comprised of college student self-injurers; future research should examine affective modulation of startle in younger participants since NSSI often begins in early adolescence, and in self-injurers from clinical contexts who might exhibit more severe emotional problems. Third, the pleasant images were not rated as arousing as the unpleasant images. Although the postpicture startle pattern was not attributable to these arousal differences, future studies should make efforts to balance image arousal ratings. Finally, as mentioned above, participants were not given specific instructions during the postpicture period; therefore it is not clear what strategies may have been using to maintain or modulate their emotional experience after picture offset.