We have quantified the effect of visual, and auditory stimulation upon the breathing pattern in resting healthy man. Only noninvasive instrumentation was used. For the visual experiment we studied 36 subjects in each of three conditions: relaxed wakefulness with eyes closed (EC); with eyes open and directed at a white screen (EO); and whilst reading a standardised text (R). For the auditory experiment we studied 18 subjects under three analogous situations: no auditory input (N); listening to white noise (W); and listening to a story (V). In each study, all subjects underwent four replications (over two days) of one of the six permutations of the three experimental conditions; each condition lasted 5 min. A balanced analysis of variance on 10,368 breaths showed that, from baseline EC, both EO and R significantly increased respiratory frequency and ventilation by approximately 6%. Using 5184 breaths in the auditory study the analysis showed qualitatively similar results between analogous situations. The results demonstrate the importance of defining the conditions under which resting VI is measured.