In a recent study published in the Scientific Reports Journal, researchers compared the responses of men and women to various olfactory stimulations.
Study: Comparable responses to a wide range of olfactory stimulation in women and men. Image Credit: Microgen/Shutterstock.com
Background
Recent research supports that females have a better sense of smell than males. Studies have shown that women excel in absolute detection, discrimination, and identification tasks compared to men.
One theory suggests that possessing a keen sense of smell may offer evolutionary benefits specific to the gender. The embryo protection hypothesis suggests that a woman's sense of smell and taste plays a crucial role in protecting the embryo during pregnancy, leading to healthier offspring.
The existence of gender-related differences in olfactory ability is still an open field of research with varying and sometimes opposed empirical findings and theoretical explanations.
About the study
In the present study, researchers examined the reactions and performance of women and men to a broader range of odor exposure outcomes.
Through public advertisement, the team recruited adult participants, including 37 women and 39 men. The study established non-parametric estimates of olfactory sensitivity (A) as well as a criterion (ln(b)) through a constant stimulus procedure.
The experiment involved using dilutions of the odorant n-butanol as stimuli, while pure tap water was used as a blank stimulus. The study employed an exposure chamber to evaluate responses to prolonged exposure to odors.
The intensity, valence, and effect on the concentration of n-butanol exposure were evaluated by participants using a Borg CR-100 scale. The category rating scale includes numerical values and verbal descriptors: 0-nothing, 1.5- minimum, 2.5- extremely weak, 6- very weak, 12- weak, 25- moderate, 45- strong, 70- very strong, 90- extremely strong, and 100- near maximal.
The top ten symptoms experienced by individuals with chemical/odor intolerance were evaluated with the Borg CR-100 scale. They included nasal mucosal irritation, eye irritation, throat irritation, skin irritation, breathlessness, difficulty concentrating, dizziness, fatigue, nausea, and headache.
The study utilized a Stroop task to assess inhibition and interference as a general estimate. In contrast, a three-back job evaluated the participant's working memory capacity and updating ability.
A BIOPAC MP100 system was also employed to record electrocardiograms (ECG) and electrodermal activity (EDA). The Chemical Sensitivity Scale was utilized to evaluate the emotional and behavioral outcomes of routine chemical exposure as reported by the individual.
The participants' sense of smell and decision-making abilities were determined on the first day. The participants completed a Stroop and three-back task as their first set of functions. On the second analysis day, participants repeated the Stroop and three-back tasks before being fitted with electrodes and placed in the exposure chamber.
The properties of the odor were rated multiple times throughout the experiment, including before chamber door closure, thrice during blank, thrice during rising, and seven times during plateau exposure. Participants rated symptoms before, during, and twice during plateau exposure.
Additionally, the team performed Stroop and three-back tasks at the beginning and end of exposure while collecting autonomic measures repeatedly. Questionnaires were completed by participants following the exposure session.
Results
The sensitivity measure analysis strongly supported the null hypothesis (H0). The study conducted for the criterion showed results in favor of H0, with comparable scores for both men and women. According to the findings, there were no significant differences between men and women regarding sensory acuity or sensory decision rule. Both sexes were found to be similar in these aspects.
No differences were noted between the sexes in assessing perceptual and symptom ratings across the period of extended odor exposure. The study found a significant difference in intensity ratings between sexes, with an estimated difference of -1.35.
However, there was strong evidence suggesting that the effect of sex should not be included in the analysis. The difference remained consistent across all time points, and significant evidence suggested no interaction between sex and time.
Also, valence ratings showed no significant difference between men and women, indicating that the effect of sex was not an important factor.
Both men and women showed a similar ability to concentrate, with a slight difference of 0.78, with strong evidence against considering the effect of sex. No sex differences were found in the analysis of cognitive task scores during extended odor exposure.
The Stroop task showed a sex difference of 0.38, with anecdotal evidence suggesting that the effect of sex should not be included. Both men and women had similar scores on the three-back tasks, and there was strong evidence against involving the impact of sex.
Conclusion
The study examined the differences and similarities in odor reactions and basic olfactory functions between men and women through various tests. The constant stimulus procedure was used to measure olfactory acuity and determine decision-making in the presence of sensory uncertainty.
The present study reported no differences in basic olfactory functioning between men and women, indicating that they are more similar than different.
Research suggests no need for yellow fever vaccine booster after initial dose