Cardiac Cycle Time Effects on Performance, Phasic Cardiac Responses, and Their Intercorrelation in Choice Reaction Time

Temporal relationships between phasic cardiac responses and choice reaction time (RT) performance were studied in 8 human volunteers using a speed-accuracy tradeoff design. “Cardiac cycle time” was varied by presenting stimuli at either the R wave of the electrocardiogram or 350 msec afterward. The speed and accuracy of choice RT performance were systematically manipulated by rewarding subjects for responding as close as possible to five different RT targets (150, 200, 250, 300, and 350 msec). The magnitude of both the cardiac deceleration which preceded stimulus onset and the cardiac acceleration which followed the response varied systematically with RT; both anticipatory deceleration and accelerative recovery were larger for faster RTs. More importantly, the timing of the shift from anticipatory deceleration to accelerative recovery varied systematically as a function of both cardiac cycle time and RT. Correlations between performance and cardiac interbeat intervals (IBIs) before, during, and after the RT were uniformly low, but showed consistent variation as a function of temporal proximity of the IBI to the stimulus. An hypothesis which relates timing of task completion, timing of vagal inhibition, and phasic cardiac responses was proposed to account for the timing of the shift from anticipatory deceleration to accelerative recovery.