Cardiac timing effects on response speed are modulated by blood pressure but not heart rate variability in healthy young adults.

Cardiac timing effects reflect the dynamic interplay between interoceptive and exteroceptive processes. Human information processing tends to be facilitated during cardiac diastole and inhibited during systole, reflecting autonomic regulation and the neuromodulation by baroreceptor afferents. Thus, blood pressure (BP) and vagally-mediated heart rate variability (vmHRV) are potential modulators of those effects. Additionally, cognitive control appears to play a critical role in the processes. However, whether cardiac timing effects are influenced by those factors remains unclear. The present study aimed to clarify these relationships. Fifty-one healthy young adults completed three experimental sessions to assess BP, short-term HRV, and cardiac timing effects. The Multi-Source Interference Task served as the cognitive task, with stimuli presented during either systole (R + 300 ms) or diastole (R + 550 ms). Repeated-measures ANCOVA and regression analyses were conducted to examine the effects of cardiac timing on response time (RT) and their associations with BP and vmHRV. Results indicated that higher BP predicted less RT slowing by systole in interference trials, while vmHRV was not linked to cardiac timing effects in interference or control trials. These findings suggest that individual differences in physiological functioning influence cardiac timing effects and contribute to better understandings of how interoceptive processes shape human cognition.