5. Discussion
This study contrasted the associations between ANS reactivity to a SSST
and the countdown task (signaled and unsignaled noise blasts). Results
provide additional evidence that an accurate characterization of
associations between ANS reactivity and psychopathy requires attention
to: 1) the stressor used to induce change, 2) the measure of ANS
activity, 3) the characterization of psychopathy, and 4) sex differences
in associations.
Analyses indicated HRR to signaled noise blasts in the countdown task
was negatively associated with SRP total scores and scores on three of
the factors in the full sample, but only the association between HRR and
SRP-IPM remained statistically significant after the sample was
restricted to females. In addition, HRR to signaled noise blasts had a
negative association with SSS-V total scores and the SSS-V disinhibition
scales in the full sample but not among females. In contrast, HRR to the
social stressor was not associated with psychopathic traits in either
the full sample or the female only subsample.
Negative associations between HRR to signaled noise blast and
psychopathic traits are inconsistent with Wang et al. (2012) and with
earlier work showing small samples of male criminal psychopaths show
increased HRR to signaled noise blasts relative to non-criminal
psychopaths (Hare, 1982; Hare et al. 1978; Ogloff et al., 1990), but fit
well within accounts of psychopathy emphasizing reduced ANS reactivity
in anticipation of aversive stimuli (e.g. Arnett, 1997; Lyken, 1995).
Wang et al. (2012) reported larger HR acceleration during signaled noise
blasts was associated with callousness-disinhibition in both boys and
girls. More recently, MacDougall et al. (2019) found no association
between HRR to noise blasts and psychopathic traits in juvenile male
offenders. Inconsistent results highlight the need for replication with
attention to the potential influence differences across the measurement
of psychopathic traits and differences across sex in associations
between ANS reactivity and psychopathy.
In the current study, SCR to both signaled and unsignaled noise blasts
during the countdown task was positively associated with SSS-V Boredom
in the full sample but not with the sample restricted to females.
Positive associations between SCR to signaled and unsignaled noise
blasts results stand in apparent contrast to negative associations and
psychopathic traits reported in earlier work, but differences may be
reconciled to a certain extent with a consideration of measurement and
variation in associations across sex. Negative associations in prior
work were reported for measures capturing Factor 1 psychopathy including
manipulative/deceitfulness (Wang et al., 2012), callous-unemotional
traits (McDougal et al., 2019), and fearless dominance (Dindo & Fowles,
2011). The current analyses found an association between SCR during the
countdown task and sensation seeking, a trait that can be conceptualized
as a facet within Factor 2 psychopathy but has little to no overlap with
the callous egocentricity that underpins much of Factor 1 psychopathy.
In addition, negative associations between SCR to noise blasts and
Factor 1 psychopathy traits may be specific to males and therefore
attenuated in our sample which was predominantly (77%) female. This
suggestion receives some support from Wang et al. (2012) who found fewer
SC responses during signaled noise blast anticipation were associated
with an increased manipulative/deceitful factor derived from Lynam’s
(1997) Childhood Psychopathy Scale among males but not females. Thus,
SCR during the countdown task may be positively associated with facets
within Factor 2 psychopathy as evidenced here, but negatively associated
with Factor 1 psychopathy among males as indicated by prior work.
Unfortunately, due to very small within stress task group sizes with the
sample restricted to males we were unable to replicate our analyses in a
male only sample.
In the results reported here, SCR during the SSST was negatively
associated with the Interpersonal Manipulation factor of the SRP-III
both in the full sample and with the sample restricted to females. This
association was somewhat surprising as Dindo and Fowles (2011) report
that SCR to the SSST was positively associated with Impulsive
Antisociality (PPI-2) but not associated with Fearless Dominance
(PPI-1). The lack of an association between Fearless Dominance and SCR
to the SSST in Dindo and Fowles (2011) would lead to the anticipation
that Interpersonal Manipulation would not be associated with SCR to the
SSST as the correlation between Interpersonal Manipulation and some of
the subscales that comprise Fearless Dominance is very strong (e.g.,
Machiavellian Egocentricity (PPI) r = .75, Seibert et al., 2011).
Nonetheless, differences across studies may be due to the measures used
or sex differences as with the association between SCR to noise blasts
and psychopathic traits discussed above.
While the focus of the current work was on differences in associations
between ANS reactivity and psychopathic traits across the countdown task
and the SSST, results also inform the associations between ANS measures
taken at rest and psychopathic traits. The current analyses found a
negative and statistically significant association between RSC and SSS-V
total scores that was present in the full sample and with the sample
restricted to females. This association is consistent with prior reports
of a negative association between RSC and sensation seeking (Gatzke-Kopp
et al., 2002; Plouffe & Stelmack, 1986). In contrast, RHR was not
associated with psychopathic traits in the results presented here.
The implications of the current work for our understanding of
associations between ANS activity and psychopathic traits should be
conditioned by consideration of certain aspects of the study’s
methodology. While the current work has virtue in that it is the first
to use a randomized design to explore differences in associations
between ANS activity and psychopathic traits across stressors, this
methodology resulted in a relatively small overall sample size and even
smaller within condition sample sizes. The study’s small sample size
increases the susceptibility to Type I error and thus limits the weight
that should be give conclusions regarding variation in association
across tasks. Risk for Type I error was also increased through multiple
comparisons. Thus, strong conclusions await replication of the
associations reported herein. However, potential differences in
associations between ANS and psychopathic traits suggests that research
in this area should consider different measures and focus on psychopathy
factors rather than total scores. This approach necessitates multiple
comparison in studies considering different aspects of ANS activity (SC
and HR), different stressors, and different measures of psychopathy. In
addition, the sample used here was predominantly female. While this can
help to shed light on the extent to which findings based on samples of
males generalize, we were unable to directly consider differences in
associations across males and females. Lastly, the sample was drawn from
university students and as such average values on psychopathy scores are
lower than at-risk or forensic samples (e.g., Sandvik et al., 2012).
Nonetheless, the current results contribute to growing evidence that
associations between ANS responsivity and psychopathic traits vary
across stress task. Within this
line of research there is accumulating evidence that ANS responsivity to
noise blasts is negatively associated with Factor 1 psychopathy (Fung et
al., 2005; McDougal et al., 2019; Wang et al., 2012). Evidence regarding
associations between ANS responsivity to SSSTs and psychopathic traits
is less consistent. Here we find a negative association between SCR
during the SSST and SRP-IPM while prior work has found evidence of a
positive association between SCR during the SSST and PPI Factor 2
Impulsive Antisociality. While differences across studies may be
attributable to the measurement of psychopathy and sex differences in
sample composition, they suggest that our understanding of the role of
ANS in the development of psychopathic traits may be furthered by
additional work paying specific attention to variation in associations
across stressor type while also considering variation across the
conceptualization and measurement of psychopathy.