Response inhibition on the stop signal task improves during cardiac contraction

Motor actions can be facilitated or hindered by psychophysiological states of readiness, to guide rapid adaptive action. Cardiovascular arousal is communicated by cardiac signals conveying the timing and strength of individual heartbeats. Here, we tested how these interoceptive signals facilitate control of motor impulsivity. Participants performed a stop signal task, in which stop cues were delivered at different time points within the cardiac cycle: at systole when the heart contracts (T-wave peak, approximately 300 ms following the R-wave), or at diastole between heartbeats (R-wave peak). Response inhibition was better at systole, indexed by a shorter stop signal reaction time (SSRT), and longer stop signal delay (SSD). Furthermore, parasympathetic control of cardiovascular tone, and subjective sensitivity to interoceptive states, predicted response inhibition efficiency, although these cardiovascular and interoceptive correlations did not survive correction for multiple comparisons. This suggests that response inhibition capacity is influenced by interoceptive physiological cues, such that people are more likely to express impulsive actions during putative states of lower cardiovascular arousal, when frequency and strength of cardiac afferent signalling is reduced.