The effects of respiration inhibition on cardiac responses were investigated during two attentional tasks: reaction time and visual search. The responses were partitioned into two sequential components: a short-latency (reactive) acceleration and a longer latency (tonic) component characterized by directional and stabilization changes. The reactive cardiac response components were independent of changes in respiratory activity. Respiration inhibition during the tonic interval was related to both cardiac deceleration and stabilization in the reaction time task but not during visual search.