Respiratory amplitude (RA) and respiratory rate (RR) parameters were examined in student subjects (Ss) following stimulation with five intensities of sound and five intensities of light. All Ss completed the MMPI and were then divided into high and low ego strength (Es) groups on the basis of their scores on the Barron scale. These groups were balanced for alertness-drowsiness by EEG criteria. High Es Ss responded with a greater increase in RA than low Es Ss and there was a strong trend for high Es Ss to respond less than low Es Ss in RR. Both RA and RR increased following stimulation with the greatest changes following greater intensities of stimulation in both modalities. Light induced a greater increase in RA and RR than sound.