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It's known that humans breathe mostly through one nostril at a time. How can we then perceive the direction the smell is coming from? Some articles claim similarity between olfactory and auditory directional perception:

The direction of a sound source can be determined binaurally by using the time difference and the loudness difference of the sound waves arriving at the two ears. Similarly, the direction of an olfactory source can be determined by using the time difference and the difference in sensation magnitude of the olfactory stimuli between the two nostrils as the air surrounding the odorous object is inhaled. Time differences of the order of 0.1 msec can be recognized—a value similar to that found in hearing.

However, that explanation runs afoul of breathing mostly through only one nostril at a time because at least the difference in sensation magnitude of the olfactory stimuli should depend heavily on which nostril is 85% shut and which one is wide open.

De Novo
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Michael
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  • HI Michael. I think your question can be solved by re-reading the source you interpreted to mean humans only "use" one nostril at a time. – De Novo Mar 11 '19 at 22:51
  • @DeNovo, if you barely breeze through the 85% closed nostril you are unlikely to smell through it with the same intensity as through the open one. That makes it unlikely that you can use at least the difference in sensation magnitude of the olfactory stimuli between the two nostrils as the air surrounding the odorous object is inhaled part of the suggested mechanism of directional olfactory sense. – Michael Mar 11 '19 at 23:10
  • I believe both the low flow and high flow nostril are used to detect smells in a given cycle. I think your question could be improved by changing "use one nostril at a time" to "breathe from one nostril at a time", since you're saying "Its known..." It is not known that humans only detect smells from one nostril at a time. – De Novo Mar 12 '19 at 00:32
  • Good edit, and I think this is a very interesting question. I just edited myself to change breeze to "breathe", which I think is what you meant. Feel free to roll back if i misunderstood. I don't have electronic access to the physiology study from the 60s you referenced, but I am very curious as to whether they took this into consideration. – De Novo Mar 12 '19 at 01:32
  • my guess is that it requires detecting differences in concentration by turning your head. – Karl Kjer Mar 12 '19 at 02:56
  • A more recent (and complete) article: https://www.nature.com/articles/srep05796 – rotaredom Mar 12 '19 at 14:38

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