Our findings suggest that gender, self-reported level of psychopathy, harm avoidance, anxiety, and startle probe timing all interact to influence affective modulation of the startle response in non-incarcerated individuals. Consistent with previous studies (Patrick et al., 1993
; Vanman et al., 2003
), men reporting high levels of psychopathy failed to show the typical augmentation of the startle response when viewing aversive stimuli. This deficit was specific to levels of emotional detachment, offering further evidence that psychopathic men have difficulty processing aversive information, and that this effect extends to non-incarcerated men.
Inconsistent with both study hypotheses and previous work, this deficit did not persist into the later probe time. This inconsistency suggests that while men with elevated levels of psychopathic characteristics generally have difficulty processing aversive information, there are additional factors, such as type or severity of psychopathic symptoms or a myriad of other individual differences that further separate responses in community versus incarcerated samples. These factors might help explain why incarcerated men with elevated levels of psychopathy show a complete deficit in their ability to process aversive information, while (presumably healthier) community samples appear to show slowed, but not completely deficient processing. This could also account for inconsistencies with Sutton et al. (2002)
finding that psychopathic women showed a deficit in processing at 2.0, but not 4.5 s probe intervals, while women in the current study showed normal responding across probe times and level of psychopathy. Unfortunately it is impossible to directly compare type or severity of psychopathy between the present sample and previous, incarcerated samples, as the change in sample in this study necessitated a change in the method of assessing psychopathy. Therefore, it is difficult to substantiate this explanation without further study.
Taken together, these data suggest that gender differences exist in the point where psychopathic characteristics interfere with affective processing. In the present study, women reporting elevated levels of psychopathy did not significantly differ from their male peers in number of psychopathic or related characteristics reported, yet they failed to show the same deficits in modulation of the startle response. Past research has indicated that while the construct of psychopathy is applicable to female samples, the factor structure differs substantially between males and female inmates (Salekin, Rogers, & Sewell, 1997
), thus potentially suggesting that women must experience greater severity or a different cluster of symptoms than do men, to produce a noticeable difficulty with affective processing. This could explain the discrepancies within the present study, as well as those between previous studies of male (Herpertz et al., 2001
; Patrick et al., 1993
) and female inmates (Sutton et al., 2002
). Discussion of potential mechanisms for gender differences, such as differences in socialization or biological make-up, are beyond the scope of this study, but warrant further investigation.
A second discrepancy is non-psychopaths’ lack of startle potentiation to the 4.5 s probe. Existing literature consistently reports a linear trend in affective startle response when blinks are elicited between 800 and 5500 ms. However, most studies average data across probe time, thus, it is possible that the same effect is present across studies, but cancelled in the averaging process. In support of this idea, the present study found a significant linear trend when the startle data were averaged across lead time for the low psychopathy group when considered alone, F(2,84) = 19.58, p < 0.001, ε = 0.92, and for all participants, F(2,189) = 53.06, p < 0.001, ε = (0.96). It was only when the data were separated by probe time that the inconsistency became apparent.
Results also indicated a relationship between individual personality characteristics and emotional modulation of the startle response. These findings extend recent research (Vanman et al., 2003
) beyond a simple relationship between emotion modulated startle and psychopathy, and provides additional support for the contention (e.g., Patrick et al., 1993
) that deficits in emotional modulation of startle are specific to characteristics associated with emotional detachment (Factor-1). Specifically, deficits were related to low levels of anxiety and harm avoidance (associated with Factor-1), but not social deviance, impulsivity, or excitement seeking (associated with Factor-2). Additionally, this effect was present for both men and women, suggesting that the influence of personality on emotional processing is similar across gender.
In closing, some limitations should be acknowledged. While researchers suggest that psychopathy may be adequately assessed via self-report, and have reported moderate correlations with the PCL-R (Lilienfeld & Andrews, 1996
; Poythress et al., 1998
), the PPI may assess a different component of psychopathy that is differentially related to affective modulation of the startle response. Future work should include both clinician-rated (e.g., PCL-R) and self-report measures of psychopathy to better characterize any differences in regard to physiological responsiveness. It also will be useful to include a broader range of personality characteristics and physiological measures, such as skin conductance and measures of functional brain activity. The latter will be especially useful in further characterizing gender differences in emotional responding, in both psychopathic and non-psychopathic individuals, as recent studies have reported gender differences in brain activation to emotional stimuli in the absence of differences in the startle response (Lang et al., 1998
; Wrase et al., 2003
In summary, gender, startle probe timing, psychopathy, and personality characteristics associated with emotional detachment, differentiated responsiveness to aversive stimuli in a community sample. Specifically, only males reporting high levels of psychopathy showed a significant deficit in affective modulation of the startle response, and then only when startle occurred early in processing. Conversely, both males and females reporting decreased levels of anxiety or harm avoidance showed a significant deficit at the earlier probe time. Results suggest that emotional processing difficulties observed in psychopathic individuals may be less extensive than previously believed, instead being mediated by the interplay of a number of factors, including levels of trait anxiety and harm avoidance. Future research should focus on further elucidating the factors that mediate the relationship between psychopathy and emotional modulation of the startle response, including gender, and type and severity of psychopathic characteristics, and examining how deficits in emotional processing may translate into deviant behavior.