The butterfly effect states that a small change in the original condition could trigger a tremendous effect in the end. In the human olfactory system, any change involving chemical, biological, physiological, and psychological aspects could lead to drastically different odor perception. When we inhale a mixture of odorants, these odorants can act as agonists, antagonists, or allosteric enhancers to the olfactory receptors, which means there could be enhancement, suppression, or no effect when mixing a new component with existing odorant(s). Furthermore, odor mixture perception, according to Stuart Firestein, is like "a chord with a silent note," meaning the components below the threshold are crucial in determining the overall mixture identity and quality.In the first study, we demonstrated the temporal effects of odor recognition by showing that subjects' detection probability across different concentrations remained consistent even when the measurements were conducted three days apart. Furthermore, we showed that by using three concentrations, we could efficiently obtain threshold measurements within a 10-minute timeframe. In the second study, we provided evidence to support the notion that the configural and elemental recognition of an odor mixture is highly influenced by experimental conditioning. We found that when subjects underwent proper conditioning, they were able to generate well-fitted psychometric functions that accurately predicted the threshold for a configurally recognized odorant mixture. This highlights the importance of conditioning protocols in studying odor mixture perception and the possibility of adopting a top-down method to study odor mixture perception. In the third study, we presented evidence demonstrating the masking effects of sub-threshold amounts of perfumery raw materials (PRMs) on the detection probability of a malodor, Isovaleric Acid. Our results revealed that sub-threshold concentrations of PRMs could reduce the detection probability of Isovaleric Acid by up to 72%. Moreover, when a mixture of six sub-threshold PRMs was employed, we observed the detection probability of Isovaleric Acid being masked by 98%. These findings offer promising applications in odor control and management. In the final study, we observed diverse responses in the perception of other odorants when sub-threshold levels of IVA were present. These effects included both enhancement and suppression, but they were not consistent across different concentrations of sub-threshold IVA. These findings highlight the complex dynamics of odor interactions and emphasize the importance of considering sub-threshold odorants in odor masking research.