Respiration shapes response speed and accuracy with a systematic time lag.

Sensory-cognitive functions are intertwined with physiological processes such as the heart beat or respiration. For example, we tend to align our respiratory cycle to expected events or actions. This happens during sports but also in computer-based tasks and systematically structures respiratory phase around relevant events. However, studies also show that trial-by-trial variations in respiratory phase shape brain activity and the speed or accuracy of individual responses. We show that both phenomena-the alignment of respiration to expected events and the explanatory power of the respiratory phase on behaviour-co-exist. In fact, both the average respiratory phase of an individual relative to the experimental trials and trial-to-trial variations in respiratory phase hold significant predictive power on behavioural performance, in particular for reaction times. This co-modulation of respiration and behaviour emerges regardless of whether an individual generally breathes faster or slower and is strongest for the respiratory phase about 2 s prior to participant's responses. The persistence of these effects across 12 datasets with 277 participants performing sensory-cognitive tasks confirms the robustness of these results, and suggests a profound and time-lagged influence of structured respiration on sensory-motor responses.