Smell processes use molecule shape and electric-field differences to distinguish odorants {smell, physiology}. After seven or eight molecules bind to cilia odorant receptors, olfactory receptors signal once. People need 40 signals to perceive odor. Odorants affect several olfactory-receptor types, which send to smell neurons that excite and inhibit each other to form intensity ratios. Smell neurons work together to distinguish odors.
Odors are painful at high concentrations. Smell can detect very low concentrations. Odor intensity and sense qualities mix.
Smell can detect source location. Smell can detect many sources from one location.
Lower air pressure increases volatility and so smell intensity. Higher humidity increases volatility and so smell intensity. Light typically decreases smell, by breaking down chemicals.
After smelling an odor, smell is less sensitive to later odors {cross-adaptation}, probably because both odors share one or more odorant-receptor types. Different odor sequences result in different sensitivities.
People can be unable to name familiar odors {tip-of-the-nose phenomenon}. Unlike tip-of-the-tongue phenomena, there are no lexical cues.
Outline of Knowledge Database Home Page
Description of Outline of Knowledge Database
Date Modified: 2022.0225