People are able to distinguish between the strength of the odor coming from one side or another, reported in Proceedings of the National Academy of Sciences. This is shown by Chinese scientists in experiments with solutions of odorous substances, for each individual the nostrils, and moving dots. Previously it was believed that the organs of smell, unlike vision and hearing, do not allow to determine the spatial characteristics of the stimuli.
Because the environment of the body is impermanent (then colder, then warmer, day gives way to night, other organisms, and sometimes inanimate objects move in space), to understand what is happening, it is desirable not only to record the appearance of the stimulus, but also how and where it moves. A person is able to determine the direction of the optic (for example, monitor whether a passerby or removed) and auditory stimuli (dogs barking from behind the fence on the right or left). Stereometrica is due to the fact that the two are essentially the same organ are at a small distance from each other, until one of them comes faster stimulus than to another, either on the one hand it is stronger than the other.
By this logic, the sense of smell also can be a volume of air with odorous substances comes on the olfactory epithelium through two nostrils, and it is theoretically possible that the left molecule compounds with the smell will reach the sensitive cells just before the right. However, in practice it turns out that people have receptors related to olfactory nerve, do not distinguish the direction of the stimulus. If a person realizes which side of him the smell, it is due to the endings branches of the trigeminal nerve. Some of them consider chemical, mechanical, thermal, and painful stimuli. Accordingly, if the air is suitable components (e.g. sulfur-containing compounds, needed for the perception of the smell of onions), or substances that provide a smell, have an irritating effect on mucous membranes (menthol), it is possible to grasp the direction of olfactory stimulus. But it is not olfaction in the strict sense of the word: the trigeminal nerve is not directly related to the olfactory centers.
Researchers from the Institute of psychology, Chinese Academy of Sciences, led by Wen Zhou (Zhou Wen) conducted experiments with stimuli that are not perceived by the endings of the trigeminal nerve in the nose. They invited a group of 216 healthy non-Smoking volunteers of both sexes to participate in several series of experiments. Subjects on the big screen during 500 milliseconds was showing 1800 pixels that flickered so that was the feeling that if they move on people. It was necessary to determine where is the center from which the moving point: right, left or in the middle. In a second after the man responded, he was shown a new set of points, and so a few dozen times.
At the same time, people are allowed to breathe through the tube (individual tube for each nostril) of vessels partially filled with an aqueous solution of vanillin or phenylethyl alcohol solution in propylene glycol. Odorous substances in the vessels was presented in different concentrations. Thus, in one nostril got more molecules of vanillin (or phenylethyl alcohol) in the other less or even not at all. Also in several series of experiments, volunteers were asked how much they think a particular smell. One of the two tubes was connected to the vessel, where there was no vanillin or phenylethyl alcohol.
It turned out that the concentration of odorants affects the perception of visual stimuli: the participants of the experiment it seemed that the points move them from the side from which the smell was stronger (p<0.01). To answer which side I feel more vanilla (or phenylethyl alcohol), they could not. Interestingly, the shear force in the perception of points associated with smells that are not dependent on the absolute concentrations of substances, and how it differs between the two nostrils. The ratio of molecules of odorous substances in solution for one nostril and the other was 4:1 was more shifted the perception of motion (p<0.001) than the ratios of 5:0 or 3:2.
It turns out that stereophonie man has a place, though it is provided not only by the branches of the trigeminal nerve and olfactory nerve. In addition, the authors suggest that odor perception with the perception of direction, they complement each other. Zhou and colleagues believe that the brain correlates the information from the visual and olfactory systems to the medial visokoi and entorhinal cortex, but to prove it, we need experiments — probably with the visualization of the activity of different brain regions.
The sense of smell is subject to many laws that work for other sensory systems. For example, you will notice people smell or not, depends on where directed his attention at the moment. If you force people to look at the screen specific letters, 40 percent do not even feel the strong smell of coffee in the room, and if the letters are to be detected among the figures (which is simpler), the smell of coffee to notice almost everything. This phenomenon is called inattention blindness (although in the case of smell it is not so much about blindness) and works at least for visual stimuli.