Self-regulation is typically operationalized in neuropsychological assessment through self-report scales and measures of attention and executive functioning. However, there have been mixed findings on the relationships between self-report measures and physiological and performance-based measures believed to represent self-regulation. Poorer self-regulation is related to an array of negative behavioral and health-related outcomes. Therefore, it is critical to understand the process of self-regulation and the relationships between measures neuropsychologists use to assess it. The current study aims to investigate the relationships between four purported measures of self-regulation: resting-state high-frequency heart rate variability (HRV; a stable individual difference variable that reflects parasympathetic capacity for adapting to changing environmental demands), behavioral performance on the Delis-Kaplan Executive Function System (D-KEFS) and the Conners Continuous Performance Test - 3rd Edition (CPT-3), and trait self-control on the Brief Self-Control Scale (BSCS). It was hypothesized that physiological and behavioral self-regulation variables would predict the BSCS, such that higher resting HRV and better performance on the cognitive measures would predict higher self-reported self-control.

Thirty-five healthy adults (Age M = 29.80, SD =8.52, 45.7% female) recruited from the community completed the BSCS, CPT-3, and D-KEFS as part of a larger battery. Participants also completed a 10-minute eyes-open resting condition during electrocardiogram recording. High-frequency power (0.15 - 0.4 Hz) was extracted and used to operationalize resting HRV. Linear regression was used to test the predictive relationships between the BSCS total score, resting HRV, CPT-3 scores, and a residualized executive functioning score from the D-KEFS that controls for non-executive lower-order cognitive processes.

Regression analyses indicated that neither the D-KEFS composite, the CPT-3 indices, nor resting HRV were related to the BSCS. Resting HRV predicted the CPT-3 Hit Reaction Time (HRT; B = -2.97, p < .05) and HRT Standard Deviation (HRT SD; B = -4.55, p < .05). Resting HRV was unrelated to the D-KEFS executive composite score. CPT-3 performance variables and D-KEFS composite score were also unrelated to one another.

Results showed that the BSCS was unrelated to resting HRV, CPT-3, and D-KEFS performance. However, higher resting HRV was related to faster and more consistent responding on the CPT-3. These findings contradict previous research showing associations between the BSCS and performance on executive functioning measures. The relationship between resting HRV and reaction time on the CPT-3 is generally consistent with literature that suggests that higher resting HRV is associated with better cognitive performance. Although the association between resting HRV and executive functioning was not significant in this modest sample, it was comparable to that reported in a recent meta-analysis. Overall, despite limitations related to the small sample size, the results raise questions regarding the construct validity of common neuropsychological indices of self-regulation. Further research is needed to clarify the nature of the self-regulation construct and the relation of neuropsychological measures of behavioral self-regulation to physiological and self-report indices.