Resting HR (RHR) and resting SC (RSC) measures were quantified as the
average value across the three-minute baseline measurement period during
which respondents watched the relaxing video. HRR and SCR were
quantified with area under the curve with respect to increase (AUCi;
Pruessner et al., 2003).11Using AUCi to quantify change in ANS
activity in response to the countdown task allowed reactivity to
signaled and unsignaled noise blasts in the countdown task to be
captured with a single measure for each condition rather than the
estimation of separate measures for change pre- and post-noise blast
for both unsignaled and signaled noise blasts. A single measure of
reactivity was preferable in order to limit the number of comparisons
between ANS measures and multiple measures of psychopathic traits.
The formula for AUCi is:
Where ti is the interval of the time between measures
and mi is the measurement itself. Following Kavish et
al. (2019), AUCi for the SSST was estimated with ANS values gathered
during the 2 minutes in which subject prepared their speech and 2
minutes of speech delivery. For the countdown task separate AUCi
measures were estimated for signaled and unsignaled trials. For both,
ANS values included in the estimation of AUCi began with the 12-second
anticipatory period before the noise blast and extended through the
20-second reactivity period after the noise blast. ANS reactivity
measures for the signaled trials (trials 1 & 3) were then averaged for
a single measure of reactivity during signaled trials, as were ANS
reactivity measures for the unsignaled trials (trials 2 & 4).
Descriptive statistics for all measures are presented in Table 1.
*Table 1*
Consistent with prior work in this area psychopathic traits were
captured with range of measures corresponding to the breadth of traits
subsumed in definitions of psychopathy including the Self-Report
Psychopathy Scale-III (SRP-III; Paulhus et al., 2016), the Inventory of
Callous-Unemotional traits (ICU; Frick, 2004), and the Sensation Seeking
Scale – Form V (SSS-V; Zuckerman et al., 1978).