4. Results
Prior to the estimation of associations between ANS activity and psychopathic traits we considered sex differences across analyses variables. Results presented in Table 1 indicate that females had higher RHR than males. There were no other sex differences in ANS measures. Males scored significantly higher on two psychopathy trait summary scores (SRP total, ICU total scores) and four subscale scores (SRP-CA, ICU-Callousness, ICU-Unemotional, LSRP-Factor 1, and the SSS-Thrill and Adventure Seeking). This pattern of association suggests that results present in mixed sex samples may be influenced by sex differences in heart rate/traits. To account for this possibility and the potential confounding effects of other demographic characteristics we test associations between ANS measures and psychopathic with partial correlations estimated using the {ppcor} package in R version 4.3.1 (Kim, 2015). Partial correlations controlling for sex, race/ethnicity and age were initially estimated in the full sample. Next, we re-estimated partial correlations with the sample restricted to females, while controlling for race/ethnicity and age. We were unable to replicate associations with the sample restricted to males due to the small number of males within condition.
*Table 2 *
Results presented in Table 2 indicate differences across tasks in associations between ANS activity and psychopathic traits in the full sample. There were no statistically significant negative associations between HRR to the SSST and psychopathic traits. In contrast, the HRR during the signaled phase of the countdown task was negatively associated with SRP-total, SRP-IPM, SRP-ELS, SRP-ASB, and the SSS-total and disinhibition scores. Variations in associations across tasks were also observed between SCR and psychopathic traits. There was a negative association between SCR during the SSST and SRP-IPM and positive associations between SCR to both signaled and unsignaled noise blasts during the countdown task and SSS-boredom. Results of analyses also indicated negative associations between RSC and SRP-ELS and SSS-total scores, while RHR in the full sample was not associated with any of the psychopathic traits under consideration here.
*Table 3 *
Next, we restricted the sample to females and performed partial correlations, controlling for age and ethnicity. Results in Table 3 confirm cross-task variation in associations between ANS and psychopathic trait measures, but the pattern of association changes somewhat with the restriction of the sample to females. In the case of HRR to the countdown task only the negative association between HRR signaled phase of the countdown task and SRP-total score remained statistically significant. In addition, there were no statistically significant associations between HRR during the SSST and psychopathic traits. Results for analyses testing associations between task related SCR and psychopathic traits among female again also somewhat relative to the full sample but continued to indicate cross task differences. The association between SCR during the SSST and SRP-IPM was again negative and statistically significant, while there were no longer associations between SCR and psychopathic traits during the countdown task. Associations between baseline ANS measures and psychopathic traits with the sample restricted to females were roughly parallel those in the full sample. As with the full sample RHR was not associated with psychopathic traits. The association between RSC and both SRP-ELS and SSS-total remained significant with the sample restricted to females and the negative association between SSS-disinhibition and RSC became statistically significant.