Analysis of physiological and psychological responses to odor stimulation

Abstract

Heart rate variability (HRV) analyses as well as Stress Response Scale-18 (SRS-18) questionnaire were used to evaluate the effect of Jasmine-odor inhalation in males and females. Healthy 15 males (26.3 ± 3.7 years) and 15 females (30.1 ± 3.4 years) participated in the experiment. Standard Lead-II ECG data were collected for resting, control and odor stimulation conditions. The instantaneous heart rate variability tachogram was interpolated with the use of cubic spline interpolation, and then, FFT was performed to find the HRV power spectrum.

HRV frequency domain analysis parameters were low frequency range (LF: 0.04 - 0.15Hz), high frequency range (HF: 0.15 - 0.4 Hz) and the ratio of normalized low frequency to high frequency (nLF/nHF). HRV time domain analysis parameters in this research were heart rate (bpm), the standard deviation of all normal to normal RR intervals (SDNN) and root mean square of successive RR intervals difference (RMSSD).

Experimental results suggest that stress of both males and females decreased after exposing to odor (p<0.05). It was also found that heart rate decreasing rate of males was faster than that of females for odor sets. SDNN and RMSSD parameter were slightly increased in both odor and control experiment but not so much difference in both males and females. The nLF/nHF ratio of males are significantly higher than females in all measurement intervals (p<0.05). This might be intrinsic character of males and females. After odor exposure, the nLF/nHF ratio was slightly decreased in male subjects while it was slightly increased for all control intervals. Decreasing the nLF/nHF ratio might link to decreasing the stress. The nLF/nHF ratio in female subjects was not so much changed in both odor and control intervals with slightly increased trend. The results indicate that ECG measurement could be used to evaluate the stress state quantitatively. It will be alternative technique for stress evaluation other than using the qualitative measurement with SRS scale.