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Differential sensitivity for smell: "noise" at the nose
Science (New York, N.Y.)
|February 25, 1977
Summary
Human smell can detect tiny chemical concentration differences, performing as well as advanced chromatographs. This olfactory ability is precise, even detecting a 5% change, challenging previous assumptions about smell limitations.
Area of Science:
- Sensory science
- Neuroscience
- Analytical chemistry
Background:
- Previous research suggested limitations in the human olfactory system's ability to detect subtle intensity differences.
- The precise detection capabilities of human smell, particularly in the vapor phase, were not fully understood.
Purpose of the Study:
- To investigate the sensitivity of human olfaction in resolving chemical concentration differences in the vapor phase.
- To compare the performance of human smell to analytical instruments like chromatographs.
Main Methods:
- Subjects were exposed to varying concentrations of chemicals in the vapor phase.
- Olfactory performance in detecting concentration differences was quantitatively assessed.
- Performance metrics were compared against the optimal performance of gas chromatographs.
Main Results:
- Human subjects demonstrated remarkable ability to discern fine differences in chemical vapor concentrations.
- In some cases, subjects could detect concentration differences as low as 5 percent.
- The study suggests that perceived limitations in olfactory intensity discrimination may stem from stimulus fluctuations rather than inherent sensory deficits.
Conclusions:
- Human olfaction possesses a high degree of sensitivity and precision in detecting chemical vapor concentrations.
- The olfactory system's performance rivals that of sophisticated analytical instrumentation.
- Fluctuations in the chemical stimulus are a significant factor influencing the perception of olfactory intensity.