The effect of voluntary breathing on reaction-time

The effect of voluntary changes in inspiratory duration on reaction time was studied in 17 normal subjects. All received a visual feedback on inspiratory duration and successively adjusted this variable to two target values which were respectively higher and slightly lower than resting level. The order of the two tasks was counterbalanced across subjects. Reaction times to auditory stimuli were measured during a key-pressing task immediately after voluntary breathing. Voluntary control of inspiration induced concomitant changes in breathing period and minute ventilation. Per cent changes in these breathing variables and in reaction times under the two conditions were analysed. Correlations were significant for period not for minute ventilation. This effect was probably due to neuromuscular rather than humoral factors.