Time-on-Task Attenuates Cardiac-Phase Modulation of Detection Sensitivity in a Cognitive Monitoring Task

Cardiac-phase modulation of perception has been observed across various cognitive tasks, but its temporal dynamics during sustained monitoring remain unclear. We examined how cardiac phase modulates detection sensitivity ( d′ ) and response criterion ( c ) during a cognitive vigilance task. Thirty-seven participants performed three successive blocks of a near-threshold detection task in which stimuli were presented during cardiac systole or diastole based on real-time ECG R-wave detection. Performance was analyzed using signal detection theory, with cardiac phase and block effects tested via linear mixed-effects models. Results showed a systolic advantage in d′ in the first block that attenuated across later blocks, whereas the cardiac-phase effect on response criterion persisted unchanged, and response time was unaffected by cardiac timing. These findings indicate that bodily states influence perceptual sensitivity, and that the embodied sensory intake may vary in prolonged monitoring tasks, offering a physiological account of vigilance changes over time.