Article 1 titled "How the Nose Copes With Nostril Rivalry "

Have you ever heard of nostril rivalry? If not perhaps youve questioned why smelling black pepper makes you sneeze or why wasabi seems to make your nerves go numb. Our nostrils become sensitized and desensitized to different scents as well as learning to become habituated to smells we are exposed to for long periods of time.
We can understand this by thinking about and comparing performance in our sense of smell to our sense of sight. A link on the Current Biology website discusses binocular rivalry. Basically if two images are placed in front of us our focus will flip-flop from one to the other, never wholly focusing on both at the same time. Just as we have two eyes that battle for sensory dominance, we have two nostrils that battle for olfaction (the sense of smell) in a similar manner.
The New York Times article discusses how the nose processes two scents at one time. Say for example you are given the crunchy scent of Granny Smith Apples in your left nostril and at the same time offered the warm spice of cinnamon at your right. The smells would not blend, and you would not be reminded of fresh apple pie just out of the oven. Instead the nose would alternate between odors.
Another experiment discussed in the article describes the way we become habituated to a smell. Lets say you are exposed to the smell of apple for three minutes, long enough to become habituated, later on after being exposed to the same scent a second time the smell would be weaker in both nostrils.
Although the article did not discuss anything further, i would go out on a limb to say that after habituating yourself to the Apple scent another experiment could be performed where you would smell both the Apple and the cinnamon at the same time. Maybe there would be dominance in the scent of cinnamon because you were not habituated to it?
If interested, the field of study that this article and its findings have opened up is called Human Olfactory Perception.